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^
REPAIRED BY
WISCONSIN
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BOOK REPAIR
PROJECT NO.
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THE GASOLINE AUTOMOBILE
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Coal Age * Electric Railway Journal
Electrical Uforld * Er^ineering News-Record
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Engineering 8 Mining Journal v Power
Chemical Q Metallurgical Engineering
Electrical Merchandising
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The present day motor car.
(Frontispiece)
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ENGINEERING EDUCATION SERIES
THE GASOLINE AUTOMOBILE
PREPARED IN THE
EXTENSION DIVISION OF
THE UNIVERSITY OF WISCONSIN
BY
GEORGE W. HOBBS, B. S.
FOBMKBLT INSTRUCTOR IN MECHANICAL ENGINEERING
IN THE UNIVERSITY EXTENSION DIVISION
THE UNIVERSITY OF WISCONSIN
AND
BEN G. ELLIOTT, M. E.
FORMERLY ASSOCIATE PROFESSOR OF MECHANICAL ENGINEERING
THE UNIVERSITY OF NEBRASKA
SECOND EDITION
COMPLETELY REVISED AND REWRITTEN
BY
BEN G. ELLIOTT, M. E.
PROFBSSOR OF MECHANICAL ENGINEERING
THE UNIVERSITY OF WISCONSIN
AND
EARL L. CONSOLIVER, M. E.
ASSISTANT PROFBSSOR OF MECHANICAL ENGINEERING
THE UNIVERSITY OF WISCONSIN
MCGRAW-HILL BOOK COMPANY, Inc.
239 WEST 39TH STREET. NEW YORK
LONDON: HILL PUBLISHING CO., Im>.
a & 8 BOUVERIE ST., E. C.
1919
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Copyright, 1915, 1919, by the
McGraw-Hill Book Company, Inc.
First Edition
Fourteen Impressions
Second Edition
First Impression, August, 1919
Total Issue, 38,500
TUX HAI'LK l'XKHH VOMK 1» X
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228211 fist*1?*/
OCT U 919
PREFACE TO SECOND EDITION
The developments in automobile practice since the first edition of
The Gasoline Automobile have necessitated some changes and revisions
in this edition. The entire book has been completely rewritten and en-
larged. Much new illustrative material has been added. The number
of chapters has been increased from ten to sixteen. Complete chapters
are now given on "Chassis and Running Gear," "Clutches and Trans-
missions," "Rear Axles and Differentials," while entirely new chapters
on "Principles of Electricity and Magnetism," " The Automobile Storage
Battery," and "Wheels, Rims and Tires," have been added.
No attempt has been made to cover all makes and models of cars
and apparatus, but the purpose of offering instruction on the fundamental
principles of automobile design, construction, and operation has been
adhered to as far as possible.
Mr. Earl L. Consoliver, Assistant Professor of Mechanical Engineer-
ing, has acted as co-author, taking the place of Mr. George W. Hobbs.
Ben. G. Elliott.
The University op Wisconsin,
Madison, Wisconsin,
July, 1919.
Vll
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PREFACE TO FIRST EDITION
The purpose of this book is admirably expressed in the following
quotation taken from the Buick instruction book: "To derive the greatest
amount of satisfaction and pleasure from the use of his car the driver
should have a complete understanding of the mechanical principles under-
lying its operation. Merely knowing which pedal to press or which lever
to pull is not enough. The really competent driver should understand
what happens in the various parts of the car's mechanism when he presses
the pedal or pulls the lever. He should know the cause as well as the
result."
When we consider the complexity of modern automobiles from a
mechanical standpoint, with the duties that are required of them, to-
gether with the fact that the great majority of them are operated by men
with little or no experience in the handling of machinery, the automobile
stands as one of the most remarkable machines that the ingenuity of
man has ever produced. The operating expense of the automobile
has already assumed a large place in the budget of the American people.
Although it is so built that the owner may secure good service from his
automobile with very little knowledge of its construction, still it is
evident that an intimate acquaintance with its details should enable him
to secure better service at less expense and at the same time to prolong
the useful life of the car.
It is with the hope of increasing the pleasure of automobile owner-
ship and reducing the trouble and expense of operation that this book is
offered. It is planned primarily for use in the University Extension
work in Wisconsin, for the instruction of those who drive, repair, sell,
or otherwise have to do with motor cars. It is largely the outgrowth
of a series of lectures on the subject which were given in twenty-three
cities of Wisconsin during the past winter.
The thanks of the authors are especially due to Mr. M. E. Faber of
the C. A. Shaler Co. for assistance in preparing the section dealing with
tire troubles, to Prof. Earle B. Norris for much of the chapter on Engines
and for editing the manuscript and reading the proof, and to the many
manufacturers who have liberally assisted in the preparation of the work
by supplying their cuts and other material.
G. W. H.
Madison, Wis.,
Sept. 15, 1915.
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CONTENTS
CHAPTER I
The Automobile
Art. Page
1. The steam propelled car 1
2. The electric car 1
3. The gasoline car 4
4. The gasoline-electric car 4
5. Types of cars 5
6. Passenger car bodies . : 5
7. Automobile bodies 8
8. Commercial cars 9
9. General principles of automobile construction 12
10. Control systems 16
CHAPTER II
The Automobile Engine
11. The gasoline engine 17
12. Cycles 17
13. The four-stroke cycle 18
14. The two-stroke cycle 20
15. The order of events in four-stroke engines 20
16. The mechanism of four-stroke engines 21
17. Pistons and piston rings 22
18. Connecting rods 24
19. The crankshaft 25
20. The flywheel 25
21. Valves 25
22. Valve operating mechanism 27
23. Valve opening and closing 29
24. Half-time gears. 29
25. The Knight engine. 30
26. The fuel charge 31
27. Ignition 31
28. The muffler 33
29. Cylinder cooling 33
30. Piston displacement 34
31. Clearance and compression 34
32. Horsepower of engines 34
33. Derivation of the S. A. E. horsepower formula 35
xi
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xii CONTENTS
CHAPTER III
Automobile Power Plants
Art. Paob
34. Multi-cylinder engines 37
35. Modern automobile power plants 38
36. Power plant support 39
37. Four-cylinder power plants 39
38. Ford power plant 39
39. White four-cylinder engine 40
40. Duesenberg engine 43
41. Guy rotary valve engine 43
42. Six-cylinder power plants 44
43. Marmon power plant 44
44. Franklin air cooled engine 47
45. The Hall-Scott engine 47
46. Chandler six power plant 48
47. Constructional features of four- and six-cylinder engines 48
48. Six-cylinder crankshafts 50
49. Camshafts 53
50. Eight- and twelve-cylinder power plants 53
51. Cadillac eight-cylinder engine 54
52. The Oldsmobile eight-cylinder engine 56
53. King eight-cylinder engine 57
54. Knight eight-cylinder engine 58
55. Firing order of eight-cylinder engines 58
56. Determining firing order of eight-cylinder engine 60
57. Packard twelve-cylinder engine 60
58. National twelve-cylinder engine 60
59. Pathfinder twelve-cylinder engine 62
60. Firing order of twelve-cylinder engines 63
CHAPTER IV
FUEL8 AND CaRBURETTINO SYSTEMS
61. Hydrocarbon oils 65
62. Refining of petroleum 65
63. Gasoline 67
64. Principles of vaporization 68
65. Testing gasoline 68
66. Kerosene and alcohol 70
67. Heating value of fuelo 70
68. Gasoline and air mixtures 70
69. Principles of carburetor construction 71
70. Auxiliary air valves 72
71. Air valve dashpots 74
72. Float chambers and floats 74
73. Metering pins 74
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CONTENTS xiii
Abt. pAai5
74. Operating conditions of the carburetor 74
75. Schebler model L carburetor 75
76. Schebler model R carburetor 77
77. Marvel carburetor 79
78. Bayfield model G carburetor 81
79. The Holley model H carburetor 84
80. Holley model G carburetor 86
81. Kingston model L carburetor 87
82. The Tillotson carburetor 88
83. Zenith model L carburetor 90
84. Stewart model 25 carburetor 91
85. Stromberg plain tube carburetor 92
86. Stromberg model H carburetor 96
87. The Hudson carburetor 98
88. Cadillac carburetor 98
89. Packard carburetor 98
90. General suggestions on carburetor adjustment and operation 99
91. Intake manifolds 100
92. Carburetor control methods 101
93. The gasoline feed system 101
94. Care of gasoline 105
CHAPTER V
Engine Lubricating and Cooling
95. Lubrication and friction 107
96. Lubricants and lubrication 107
97. Test of lubricating oils 108
98. Gas engine cylinder oil 109
99. Systems of engine lubrication 110
100. Full splash system of lubrication Ill
101. Splash system with circulating pump 112
102. Pressure feed and splash lubrication 114
103. Pressure feed system 114
104. Pull pressure or forced feed system 116
105. Oil pumps 116
106. Engine lubrication in general 118
107. Cylinder cooling 118
108. Thermosyphon cooling system 120
109. Pump or forced system of water circulation 121
110. Packard cooling system 122
111. Cadillac cooling system 123
112. Air cooling 125
113. Radiators 126
114. Temperature indicators 127
115. Cooling solutions for winter use 127
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xiv CONTENTS
CHAPTER VI
Principles op Electricity and Magnetism
Art. Pack
116. Electricity • 131
117. Conductors and non-conductors 131
118. Hydraulic analogy of electric current 132
119. Resistance 132
120. Relation between current, voltage, and resistance 133
121. Electrical power 134
122. Effects of electric current 134
123. The dry cell 135
124. The storage battery 136
125. Wiring of ignition batteries 137
125. Magnetism 139
127. Natural and artificial magnets 139
128. Magnetic and non-magnetic metals 139
129. The poles of a magnet 140
130. The magnetic field 141
131. Electromagnetism 142
132. The electromagnet 143
133. To determine the polarity of an electromagnet 144
134. Electromagnetic induction 144
135. The right-hand rule 146
CHAPTER VII
Battery Ignition Systems
136. Automobile ignition 147
137. The low^tension coil for make-and-break ignition 147
138. The induction coil 148
139. The safety gap 151
140. The condenser 151
141. The vibrating induction coil 153
142. The three terminal coil 154
143. The vibrating type ignition system 154
144. Timers 155
145. Spark plugs 156
146. Spark plug testing 158
147. Typical battery ignition system 159
148. The distributor 160
149. The ignition resistance unit 160
150. Spark advance and retard 161
151. Automatic spark advance 162
152. The Atwater-Kent ignition system — open circuit type 163
153. The Atwater-Kent ignition system, Type CC 167
154. The Connecticut battery ignition system 169
155. The Remy ignition system 174
156. The Remy-Liberty ignition breaker for U. S. Military Truck 178
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CONTENTS xv
Art. Page
157. The North East ignition system • 178
158. The Delco ignition system 181
159. Delco ignition breakers for eight- and twelve-cylinder engines 184
160. Timing battery ignition with the engine 185
161. Care of battery ignition system 186
CHAPTER VIII
Magnetos and Magneto Ignition
162. Magneto classification 187
163. Magneto magnets 187
164. lines of force 188
165. Types of magnets • 188
166. Mechanical generation of current 189
167. Low- and high-tension magnetos 190
168. Armature and inductor type magnetos 191
169. Current wave from a shuttle- wound armature 191
170. Low-tension magneto ignition system with interrupted primary current . . 193
171. Low-tension magneto ignition system with interrupted shunt current . . . 194
172. Dual ignition systems 196
173. Splitdorf low-tension dual ignition system with type T magneto 197
174. Remy inductor type magneto 198
175. The Ford ignition system 202
176. The high-tension magneto 205
177. The Bosch high-tension magneto 205
178. The Bosch high-tension dual system 215
179. The Bosch high-tension magneto, type NU4 217
180. The Eisemann high-tension magneto, type G4 220
181. The Eisemann high-tension dual magneto, type GR4 225
182. Timing of the Eisemann magneto to the engine for variable spark .... 227
183. The Dixie magneto 229
184. General instruction for high-tension magneto care and maintenance . . . 233
CHAPTER IX
The Automobile Storage Battery
185. Function of the battery 237
186. Construction 237
187. The plates 238
188. Positive and negative groups 238
189. Elements 238
190. Separators 239
191. The electrolyte 242
192. Jars and covers 242
193. Cell arrangement 243
194. Battery box 243
195. Markings of the battery 244
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xvi CONTENTS
Art. Paob
196. Voltage of the battery 244
197. Battery capacity 244
198. Principle of operation 245
199. Effect of overcharging 245
200. Effect of undercharging 245
201. Heat formed on charge and discharge 246
202. Evaporation of water 246
203. Necessity of adding pure water 247
204. Cause of specific gravity change . » 247
205. The hydrometer 247
206. Hydrometer readings 248
207. Variation in cell readings 248
208. Variation in hydrometer readings caused by temperature 249
209. Freezing temperature of the battery 250
210. Results of freezing 251
211. Battery charging 252
212. Detailed instruction for charging batteries 254
213. Battery testing with the voltmeter 255
214. Sulphation 256
215. Effect of overfilling 257
216. Corroded terminals 258
217. Disintegrated and buckled plates 258
218. Sediment 260
219. Conditions causing the battery to run down 260
CHAPTER X
Starting and Lighting Systems
220. Automobile starters 263
221. Mechanical starters 263
222. Air starters 263
223. Acetylene starters 263
224. Electric starters 264
225. Hydraulic analogy of an electric starting and lighting system 266
226. Generator drives 268
227. Starting motor drives 270
228. The bendix drive 273
229. Motor-generator drives 275
230. Construction of the dynamo 277
231. The simple alternating-current generator 280
232. The simple direct-current generator 281
233. The simple direct-current motor 282
234. The shunt-wound generator 284
235. Conditions which prevent a generator from building up 286
236. Types of field winding 287
237. The reverse current cut-out 28t
238. Regulation of the generator 29(
239. Generator regulation through reverse series field winding 291
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CONTENTS xvii
Abt. Paqb
240. Current regulation of the generator through vibrating type relay 293
241. Voltage regulation of the generator through vibrating type relay .... 295
242. Combined current and voltage regulation of the generator through vibrating
type relay 297
243. The Ward Leonard automatic controller 298
244. Third brush regulation 300
245. Characteristics of third brush regulation 304
246. The Remy generator with thermostatic control 304
247. The Remy starting and lighting system with relay regulation 307
248. The Bijur generator with constant voltage regulation 310
249. The Westinghouse starting and lighting system— voltage regulator type. . 311
250. The Westinghouse starting and lighting system — third brush type .... 315
251. The North East starting and lighting system on the Dodge car 318
252. The Delco single-unit starting, lighting, and ignition system on the Buick . 322
253. The Delco two-unit starting, lighting, and ignition system on the Olds-
mobile Eight 327
254. Delco-Iiberty lighting system on U. S. standardised military truck — class B. 330
255. The " F. A. Liberty " Ford starting and lighting system 334
256. Automobile lamps and reflectors 338
257. Care of starting and lighting apparatus 340
CHAPTER XI
The Automobile Chassis and Running Gear
258. General arrangement of chassis 343
259. Frames 343
260. Springs and spring suspension 345
261. Unsprung weight 355
262. The front axle 356
263. Steering system 357
264. Steering gear 358
265. Brakes 360
266. Transmission brake 363
267. Effectiveness of brakes 363
268. Antifriction bearings 364
CHAPTER XII
Clutches and Transmissions
269. The automobile clutch 367
270. The cone clutch 367
271. The disc clutch 371
272. Operation of clutch ....................... 375
273. Change gear sets 375
274. Operation of the gear set ...................... 378
275. lubrication of the transmission ................... 379
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xviii CONTENTS
Art. Page
276. Gear shift levers 379
277. Location of transmission 380
278. The planetary transmission 380
279. Operation of planetary transmission 383
280. Universal joints and propeller shaft 386
281. Lubrication of universal joints 387
282. Flexible couplings 387
283. Propeller shaft 387
CHAPTER XIII
Rear Axles and Differentials
284. Final drives 389
285. Bearings for final drive 391
286. Types of rear axles 391
287. Simple live rear axle 392
288. Semi-floating rear axles 392
289. Three-quarter floating axle 394
290. Full-floating rear axle 396
291. The differential 396
292. M. & S. differential or Powrlok 398
293. Lubrication of rear axle and differential 400
294. The torque arm 400
295. Strut rods 402
CHAPTER XIV
Wheels, Rims, and Tires
296. Wheels . . 403
297. Wooden wheels 404
298. Wire wheels 405
299. Other types of wheels 406
300. Rims . . 407
301. Removal of demountable rims 410
302. Types of tires 411
303. Construction of tires 412
304. Proper use and care of tires 415
305. Proper inflation 415
306. Tires of proper size 417
307. Care in application of tires to rims 418
308. Rim irregularities 418
309. Flat tires 418
310. Fabric bruises 419
311. Improper braking 419
312. Tight chains 420
313. Wear of tire by parts of car 421
314. Alignment of wheels 421
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CONTENTS xix
Abt. Paoe
315. Ruts and car tracks 421
316. Neglected injuries 422
317. Oil on tires .422
318. light and heat 422
319. Fast driving 422
320. Poorly made repairs 423
321. Tire powder 423
322. Inserting inner tubes 424
323. Care of spare tubes 424
324. Leaky air valves 425
325. Tire fillers 425
326. Tire protectors ^ 425
327. Spare casings 425
328. Care of tires — car in storage 425
329. Repair of tires. .' 426
CHAPTER XV
Automobile Troubles and Remedies
330. Classification of troubles 427
331. Power plant troubles 427
332. Mechanical troubles in engine 431
333. Carburetion troubles 437
334. Ignition troubles 438
335. Starting troubles 444
336. Lighting troubles 445
337. Lubricating and cooling troubles 448
338. Transmission troubles 450
339. Chassis troubles 450
CHAPTER XVI
Operation and Care
340. Preparations for starting 453
341. Starting the engine with the electric starter 455
342. Cranking by hand 455
343. How to drive 456
344. Use of the brakes 457
345. Speeding 458
346. Speedometers 459
347. Care in driving 459
348. Driving in city traffic 460
349. Skidding 461
350. Knowing the car 463
351. The spring overhauling 463
352. Washing the car 465
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xx CONTENTS
Art. Paqb
353. Care of the top 466
354. Cleaning the reflectors 466
355. Care of tires 466
356. Figuring speeds 468
357. Insurance 469
358. Interstate regulations 469
359. Canadian regulations 470
360. Touring helps. Route books 471
361. Cost records 471
Index 475
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THE GASOLINE AUTOMOBILE
CHAPTER I
THE AUTOMOBILE
Automobiles may be classified according to the type of power plant
used, as steam, electric, gasoline, and gasoline-electric; or they may be
divided into two classes according to use, as passenger cars and com-
mercial cars.
1. The Steam Propelled Car. — The steam engine, when used on an
automobile, has the advantage of being very flexible. All operations
such as starting, stopping, reversing, and acquiring changes of speed
can be done directly through the throttle on the steering wheel. By
opening or closing the throttle, more steam or less steam is supplied to
the engine, and the power is increased or decreased in proportion. When
the car is climbing a hill, it is necessary only to give the engine more
steam. This results in more power being delivered. The fact that the
steam engine is able to start under load eliminates the clutch and also
the transmission or change speed gears, the engine being connected
directly to the rear axle. The arrangement of the parts on the Doble
steam car is illustrated in Fig. 1.
The disadvantage of the steam propelled car is that it sometimes
requires considerable time to raise the steam pressure before starting.
This is especially true if the boiler has been allowed to cool off. If
it is desired to keep the steam pressure up so that the car can be started
without loss of time, a pilot light must be kept burning under the boiler
at all times. The steam pressure carried is very high, and this means
that constant care and attention must be given to the boiler and its
accessories. The steam car requires that the boiler be filled with water
for making steam every 150 to 250 miles. Kerosene is generally used
for heating the boiler.
2. The Electric Car. — The advantages of the electric car are similar
to those of the steam car. The electric motor is very flexible in operation
and can be operated entirely by the control levers. By supplying
more current or less current to the motor the power is increased or de-
creased accordingly. The electric car is especially adapted to the use
of women and children in cities. It is an easy riding car, clean, and
runs quietly.
1
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THE GASOLINE AUTOMOBILE
tlOTOR dc FAN'"
THROTTLE VALVE— *k
HAND BRAKE
IGNiT/ON AND--
LIGHTING SWITCH
CRANK CASE
AND DIFFERENTIAL^
HOUSING
BRAKE COOLING
FLANGES
^CONDENSER
STEAJ1
GENERATOR
-SERVICE BRAKE
-WATER TANK
— THROTTLE CONTROL
CYLINDERS ■-■
FRONT END
-ENGINE SUPPORT
.^ WATER PUMPS
ELECTRIC MOTOR
GENERATOR
KEROSENE
TANK
Fio. 1. — Chassis of Doble steam car.
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THE AUTOMOBILE
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4 THE GASOLINE AUTOMOBILE
The disadvantages are that it is not suitable for long drives, heavy
roads, or hilly country. On one charge of the battery the average car
will run from 100 to 150 miles, depending on the speed of the car and
the condition of the roads. If the car is run at high speed, the battery
will not drive the car as far as it will when running at a moderate rate.
This car is also limited to localities where there are ample facilities for
charging the storage batteries.
3. The Gasoline Car. — The gasoline engine is very economical as an
automobile power plant. After being started, it has great flexibility.
It is especially adapted for touring purposes and does not require any
great attention from the operator. The average car carries enough
fuel to run it 200 to 400 miles. It is then necessary to refill the gaso-
line tank. Occasionally, a quart or two of water should be put into the
. radiator. With proper care, the engine will run as long as the gasoline
supply and the electrical system hold out.
The disadvantages of the gasoline engine as compared with those of
the steam engine or electric motor are, first, the gasoline engine is not
self -starting; and, second, it lacks overload capacity. On account of
these two factors some method of changing the speed ratio of the engine
to the rear wheels is necessary in order to acquire extra power for start-
ii ig the car, for climbing hills, for heavy roads, and also for reversing
tlK ^ car» as *^e ordinary four-stroke automobile engine is not reversible.
The Qosoline engine will not start under load. This necessitates the use
of a c lutch, so that the engine can be started and speeded up before any
load is thrown on. Apparently, there are a great many disadvantages
to the g vsoline engine but in reality they are very few, for with the proper
handling °f the spark and throttle control levers it is not necessary to
keep chan ^g gears continually. The gear shifting lever need not be
used excep f' f°r starting, stopping, hill climbing in congested districts,
and on bad . toads.
The ad va* stages of the gasoline engine for use on an automobile are
so numerous tl ^ it is universally used for driving pleasure and com-
mercial cars. 1 \ure 2 is a plan view of a modern gasoline driven
automobile.
4. The Gasolint Velectric Car. — The gasoline-electric or the dual-
power car is driven h, Y a combination of a gasoline engine and an electric
motor. This arrange. Xient, illustrated in Fig. 3, gives the advantages
of both the gasoline car #nd the electric car. The electric motor is con-
nected directly to the ^Vopeller shaft running to the rear axle. By
means of a magnetic clui^h, the gasoline engine can be connected to
the shaft of the motor. there are no change gears or transmission.
The car is started by the e Vctric motor, and, after a certain speed is
attained, the engine may be started by a magnetic clutch. Power for
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THE AUTOMOBILE 5
running may be obtained either from the electric motor and batteries,
from the engine alone, or from both.
6. Types of Cars. — In general, there are two types of motor cars —
passenger cars and commercial cars — the names indicating the use for
which each type is intended. The parts of the passenger and commercial
car are similar except that in the passenger car the construction is
lighter than in the commercial car. In the passenger car everything is
planned for comfort and speed, while the commercial car is built for
heavy loads and is generally intended to be driven at lower speeds.
6, Passenger Car Bodies. — The principal types of bodies for passen-
ger cars are the roadster, the touring car, the coupS, the sedan, the limou-
sine, and the town car. These are shown in Fig. 4.
MAGNETIC
CLUTCH,
PROPELLER.
SHAFT
STORAGE
BATTERIES
GASOUNE
ENGINE
MOTOR
GENERATOR
Fia. 3. — Chassis of dual power car.
The roadster body is open and usually has one seat for either two or
three persons. Occasionally, both front and rear seats are provided,
increasing the seating capacity to four. In this case, the front seat is
divided by an aisle which furnishes the entrance from the front doors
to the rear seat. The name doverleaf is sometimes given to this type of
roadster body. The seating arrangement of the Chandler four-pas-
senger roadster is seen in Fig. 5.
In the touring car body, which is also open, rear seats with separate
rear doors are provided. The seating capacity is for five or even seven,
in which case two additional folding seats, in front of the rear seat, are
provided. In some cases only rear doors are provided, the entrance to
the front seats being through the aisle. Figure 6 illustrates a seven-
passenger touring car with the two auxiliary folding seats in front of
the rear seat.
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THE GASOLINE AUTOMOBILE
The coupS is similar to the roadster excepting that it is enclosed and
inside operated. It has seating capacity for two or three, and quite
often a small seat which faces backward provides for another passenger.
When a coup6 is provided with a detachable top or sides as in Fig. 7,
it gives all the advantages of an open roadster. Such a coup6 is some-
times called a convertible coup6 or cabriolet
The sedan is practically an enclosed touring body. It may be of
the single or two door type. If of the single door type, the front seat
Roadster.
Touring car.
Coupe.
Sedan.
Limousine. Town car.
Fig. 4. — Types of passenger car bodies.
is divided by an aisle to furnish an entrance. In some types of sedan
bodies, the sides can be removed during summer use, giving practically
all the advantages of an open touring body. A double door sedan is
illustrated in Fig. 8.
The limousine is a closed body, seating three to seven persons,
with the driver's seat in front covered with a top. If the driver's seat is
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THE AUTOMOBILE
Fiq. 5. — Seating arrangement of Chandler four passenger roadster.
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THE GASOLINE AUTOMOBILE
open and not covered, the body is called a brougham or town car. If on
either a limousine or town car, arrangements are provided for throwing
open the housing of the rear seat, Fig. 9, the body is called a landauht.
Fia. 6. — Seven passenger touring car with auxiliary rear seats.
7. Automobile Bodies. — Automobile bodies are usually made of
pressed steel, combining both strength and lightness, and built up on
wooden frames, as indicated in Figs. 10 and 11. Some bodies are built
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THE AUTOMOBILE
9
of sheet aluminum which is considerably lighter than the other metals,
but is more costly and is not so serviceable as the pressed steel.
8. Commercial Cars. — Commercial cars are built for light, medium,
or heavy duty. They are usually classified as delivery cars and trucks.
Fig. 7. — Convertible coup6 body.
The delivery cars are lighter and are usually driven at higher speeds
than the trucks, which are for heavier and slower service. Some typical
commercial cars are illustrated in Fig. 12. Commercial cars are built
Fig. 8. — Double door sedan body.
on the same fundamental principles as passenger cars, but the construc-
tion is heavier and more sturdy. In a great many cases, passenger cars
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THE GASOLINE AUTOMOBILE
Fiq. 9. — Limousine — Landaulet body.
Fio. 10. — Wooden frame for automobile body.
Fiq. 11. — Pressed metal automobile body.
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THE AUTOMOBILE
11
Ford light truck chassis.
Kissel medium truck.
Packard heavy truck.
Fiq. 12. — Typical types of commercial cars.
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12 THE GASOLINE AUTOMOBILE
are converted for commercial use by putting on a body adapted for
commercial purposes.
9. General Principles of Automobile Construction. — The two prin-
cipal divisions of an automobile are the body and the chassis. The
chassis includes all parts, with the exception of the body and its im-
mediate attachments. The frame, springs, axles, wheels, steering gear,
power plant, clutch, transmission system, and control apparatus go to make
up the automobile chassis. These parts are fully illustrated in Figs. 2
and 13.
Frame. — The frame may be called the foundation of the automobile
because it furnishes the support for the body, engine, transmission
system, etc. It must be strong, light, and at the same time not too
rigid. It is desirable to have the frame as long as possible as this in-
creases the wheel base, giving an easier riding car. The wheel base is
the distance measured between the centers of a front and rear wheel.
Frames are usually made of steel although some wooden frames are used.
Springs. — As on any type of vehicle, springs must be provided to
take the jars and bumps, due to rough roads, and to make an easy
riding car. Springs of the laminated leaf type are attached to the frame,
providing a flexible connection between the frame and the front and rear
axles. In most cases four springs are used, but on some of the lighter cars
only two springs, one front and one rear, are provided.
Front Axle. — The front axle which carries the weight of the front of
the car is generally of the solid type and is attached directly to the front
springs. Unlike the front axle on a wagon or carriage, the front axle on
an automobile does not turn on a fifth wheel for the purpose of steering,
but is fixed to the springs. Movable spindles, which carry the wheels,
are provided on the axle ends for the purpose of steering. These spindles
are tied together by a rod so that they move both wheels in the same
direction when the car is being turned. The steering of the car is done
by the steering wheel and its connection to the front wheels, as indicated
in Fig. 14. The front wheels support the weight of the front of the car
and serve for steering purposes but in most cases do not assist in driving
the car.
Power Plant. — The power for driving an automobile is furnished by
the engiqf which is supported on the front of the frame. In some cases
a sub-frame, attached to the main frame, supports the engine, which is
placed parallel to the sides of the frame. Most of the engine auxiliaries
are placed either on or very near to the engine itself. The radiator is
supported on the frame in front of the engine. The gasoline tank, in
which the fuel is carried, is placed either at the extreme rear of the frame,
or above and close to the engine, such as under the front seat.
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THE AUTOMOBILE
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i.
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3
i
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THE GASOLINE AUTOMOBILE
Clutch. — It is sometimes necessary that the engine be run when the
car is not moving, so a device has been provided to disconnect the engine
from the car driving mechanism. This device is called the clutch. If a
clutch were not provided it would be necessary to stop the engine every
time the car stopped. It would also be impossible to start or run the
engine without having the car move. The power from the engine is
delivered through the clutch to the change gears, or transmission, as it is
usually called.
Change Gears or Transmission. — The transmission is a system of
gears which makes it possible to change the speed ratio of the engine
and the car. When the car is being started, or, when going up steep
STEERING WHEELS
'STEERING KNUCKLE ^SOL tO FRONT AXLE
Fiq. 14. — Method of steering an automobile.
hills, it is necessary that the engine run comparatively fast with respect
to the car. After the car has gotten up speed, the engine can be run
slower with respect to the car speed. The change gears also furnish the
means for reversing the direction of the car. The change gears are
usually placed at the front of the propeller shaft, but occasionally are
found at the back of the propeller shaft, near the rear axle. From the
transmission or change gears the power from the engine goes to the pro-
peller shaft, which revolves and delivers the power back to the rear axle.
On account of the fact that the propeller shaft does not run in a straight
line with the engine shaft, a flexible coupling, usually a universal joint,
is used to transmit the power at an angle to the rear axle.
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THE AUTOMOBILE
15
Rear Axle. — The power is delivered by the propeller shaft to the
rear axle, which turns in its housing. The axle is divided in the center,
each half being fastened to one of the rear wheels. The power is de-
livered' through the axle to the two rear wheels. This type of axle,
Fio. 15. — Live type of rear automobile axle.
Fig. 15, in which the power is transmitted by a divided shaft revolving
inside a housing, is called a live axle.
Differential. — 1^ is sometimes necessary, as when turning a corner,
that one rear wheel turn faster than the other one. In order to accom-
SPEEDOMETtn
COMPARTMENT
StAvK* ohmi r*(Mft
EMERGENCE BRAKE. LEVEft
CONTROL UVC*
Fio. 16. — Left-hand drive, center control.
plish this, the differential is placed between the two halves of the rear
axle. The use of the differential permits each rear wheel to be fastened
to the rear axle and at the same time move at different speeds while
delivering power:
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16 THE GASOLINE AUTOMOBILE
Wheels. — Automobile wheels are of either the wooden or wire type.
Both of these types carry a rim on which is fitted a pneumatic tire filled
with high pressure air. The tire serves as a good shock absorber and
eliminates a large part of the road jars before they reach the mechanism
of the car. The distance measured between the two front wheels or the
two rear wheels is called the tread of the car. It is usually standard,
being 56 in. The rear wheels, being the driving wheels, are equipped
with brakes so that the car may be stopped or slowed down very quickly.
Usually two sets are provided, one for ordinary service called service
brakes, and the other for emergency purposes called emergency brakes.
Both sets of brakes are controlled from the driver's seat.
Fio. 17. — Right-hand drive with right control.
10. Control Systems. — The seat for the person driving an automobile
is generally on the left side, although the right-hand drive, formerly
used to a large extent, is still in use. With the left drive, Fig. 16, the
control levers for the change gears and the emergency brake are near the
center, being within ready reach of the driver's right hand. The clutch
pedal and service brake pedal are on the left, so as to be operated by the
driver's feet. With the right-hand drive, Fig. 17, the steering wheel and
foot pedals are placed on the right of the car, with the control levers to
the right of the driver, when seated.
The following chapters will treat in detail the various parts of th€
automobile, their construction, and methods of operation.
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CHAPTER II
THE AUTOMOBILE ENGINE
11. The Gasoline Engine. — Practically all gasoline engines are
driven by explosions which take place within the cylinder of the engine
and drive the piston, thus causing rotation of the revolving parts of
the engine. These explosions are in a way very similar to the explosions
of gunpowder or dynamite. When a charge of gunpowder is fired in a
cannon or gun, the gunpowder burns and produces gases which expand
and exert a tremendous pressure on the shell and force it from the gun.
Practically any substance that will burn can be exploded if under
the proper conditions. An explosion is merely the burning of some
material almost instantaneously, resulting in a great amount of heat
being generated all at once. When any substance burns, it unites
rapidly with oxygen from the air. In order to have an explosion, it
is necessary to have the fuel very finely divided and carefully mixed
with air, so that the burning can be very rapid. Then, if the fuel
is ignited, by an electric spark or any other means, the flame instantly
spreads throughout the mixture and an explosion occurs. In a gasoline
engine, gasoline vapor mixed carefully with air is taken in. This mixture
is then exploded inside the cylinder of the engine. The force of this
explosion drives the piston, and the motion is transmitted through the
connecting rod to the crank. To make the process continuous and keep
the engine going, it is necessary to* automatically get rid of the burnt
gases from the previous explosion and to get a fresh charge into the
cylinder ready for the next explosion. This process must be carried out
regularly by the engine, in order to keep it running.
12. Cycles. — There are two principal systems in use for carrying
out the series of operations necessary for getting a fresh charge of gas
into the cylinder, exploding it, and getting the burnt gases out of the
cylinder again. These systems, or rather the series of operations, are
called cycles, and the engines are named according to the number of
strokes it takes to complete a cycle. These two cycles, or systems of
strokes, are the four-stroke cycle and the two-stroke cycle.
It must be remembered that a cycle refers to the series of operations
the engine goes through. In the four-stroke cycle it requires four
strokes or two revolutions to complete the cycle. In the two-stroke
cycle, two strokes or one revolution are necessary. Many people leave
2 17
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18 THE GASOLINE AUTOMOBILE
out the word stroke and talk of four-cycle engines and two-cycle engines.
This causes the misunderstanding that many people have as to just what
a cycle really is. A better way is to call them four-stroke engines and
two-stroke engines. •
13. The Four-stroke Cycle. — Figures 18, 19, 20, and 21 show an
engine which operates according to the four-stroke cycle. The engine
shown here is a vertical engine, that is, the cylinder is placed above the
crankshaft (instead of being at one side) and the piston moves up and
down in the cylinders. This is the prevailing form for automobile
engines;
Any engine consists of four principal parts: the cylinder, which is
stationary and in which the explosion occurs; the piston, which moves
within the cylinder and receives the force of the explosion; the connecting
rod, which takes the force from the piston and transmits it to the crank;
and the crank, which revolves and receives the force of the explosion as
the piston goes in one direction, and which then shoves the piston back
to its starting point. When the piston is at the top end of its stroke,
and the engine crank also in its extreme upper position, the engine is
said to be on its upper dead center. When the piston and crank are in
the extreme lower positions, the engine is on lower dead center. A four-
stroke engine has a number of other minor parts, the uses of which wW
be brought out later.
This engine uses four strokes of the piston to complete the series
of operations from one explosion to the next, and is, therefore, said
to operate on the four-stroke cycle, or it is said to be a four-stroke en-
gine. The first illustration, Fig. 18, shows the engine just beginning
to draw in a mixture of gas and air through the inlet or intake valve.
This is continued until the piston gets down to the bottom of the stroke,
and the cylinder is full of this explosive mixture. This operation is called
the suction stroke. Then the valves are shut, as in Fig. 19, and the piston
is forced back to its top position. This squeezes or compresses the gas
into the space left in the top of the cylinder. This process of compressing
the gas is called the compression stroke. After the piston gets to the top,
the gases are ignited or set fire to and burn so quickly that an explosion
results and the piston is driven down again, as in Fig. 20. This is called
the expansion or working stroke. When the piston reaches the bottom
of the stroke, the exhaust valve is opened, and while the piston is return-
ing to the top position it forces out through this valve the burned gases
which occupy the cylinder space. This is the exhaust stroke. The engine
is now ready to repeat this series of operations. A stroke means the
motion of the piston from either end of the cylinder to the other end.
Consequently, there are four strokes in the cycle of operations of this
engine, and we, therefore, call it a four-stroke engine.
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THE AUTOMOBILE ENGINE
19
SFARK RJLKS
NLET VALVE
JACKET-
COOLINO WATCI
Suction Stroke
Fiq. 18.
Compression Stroke
Fiq. 19.
Working .Stroke
Fig. 20.
Exhaust Stroke
Fiq. 21.
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THE GASOLINE AUTOMOBILE
14. The Two-stroke Cycle. — The two-stroke cycle engine, Figs. 22
and 23, completes the cycle of events, suction, compression, explosion,
and exhaust, in two strokes of the piston instead of four. The engine,
instead of having valves, as in the four-stroke cycle type, has exhaust
and intake ports, or openings, cast in the sides of the cylinders. These
ports are uncovered by the piston as it moves up and down in the cylinder.
During the power stroke of the piston, the fuel for the succeeding charge
is partially compressed in the engine crank case. When the piston is
nearing the end of its power stroke, it uncovers the exhaust port, permit-
ting the burned gases to escape; shortly after, the intake port is uncovered
and the partially compressed charge from the crank case rushes into the
cylinder. On the return stroke of the piston, the intake and the exhaust
Spark fQug
Exhaust Port
Transfer fhrt
Check Valve (Open)
Transfer Port
Check Valve (Oastd)
Fio. 22.
Fio. 23.
Fios. 22 and 23. — Two-port, two-stroke engine
ports are closed, and the gases are compressed for the following power
stroke. The two-stroke cycle engine for automobile use has been
practically discarded.
15. The Order of Events in Four-stroke Engines. — The periods in
the four-stroke cycle are represented on the diagram of Fig. 24. This
figure represents the two revolutions of a four-stroke cycle so as to show
the crank positions when the different events occur. The diagram is
drawn for a vertical engine with the crank revolving to the right. This
is the direction of rotation of an automobile engine to a person standing
in front of the car looking toward the engine.
Let it be assumed that the engine piston has reached the top of the
stroke and has started back on the return stroke. The crank of the
engine will also be moving down until at point A when the crank angle
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THE AUTOMOBILE ENGINE
21
will be around 10°, the inlet valve opens. From A to B the suction
stroke of the piston takes place, the inlet valve closing about 20° to 30°
past the lower dead center. The inlet valve has thus been open 180° to
200°. From crank position at B to crank position at C, the gas is com-
pressed, both valves being closed. From 5° to 10° before the upper dead
center is reached, the gas is ignited and the burning or combustion occurs
from the crank position at C to the crank position at D, or during a period
of from 5° to 10°. The full force of the explosion is exerted just as the
crank passes the upper dead center and the piston begins to descend.
From crank position at D to that at E, the expansion of the gases takes
place. At E, which is from 30° to 45° before lower dead center, the
UPPER DEAD CENTER
COM5USTION
EXHAUST
LOWER DEAD CENTER
Fio. 24. — Order of events in the four-stroke cycle.
exhaust valve opens permitting the gases to be exhausted while the
crank is moving from E around to F where the exhaust valve closes a
few degrees past the upper dead center. One complete cycle has now
been completed.
16, The Mechanism of Four-stroke Engines. — The details and the
mechanism of a four-stroke automobile engine with four cylinders are
shown in Figs. 25 and 26. The cylinders are cast in one piece from grey
iron, which is the usual material for cylinders. The grey iron flows
easily when being cast, is easy to machine, and presents a good wearing
surface to the pistons. The water jacket around the cylinder is generally
made a part of the cylinder casting, although some jackets have been
made of copper and put on around the cylinder casting. The design of
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THE GASOLINE AUTOMOBILE
the water jacket is very important as sufficient cooling surface must be
provided and all pockets where steam might collect must be avoided.
VALVE ' fPRINGS VALV£S
WRIST PIN ^ ^^flonA M
COOLING, H ~**i*&jj
SPACE ^M
flYftHFFf
\t^'5ISAFr
\ ^
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MAIN BEARING
MAIN BEARING
Fio. 25. — Continental four cylinder engine.
The cylinder head can be either cast solid with the cylinder as in Fig.
26, or cast singly and made removable, being fitted to the cylinder by
means of a gasket or a ground joint. The removable head provides easy
access to the cylinder for working pur-
poses. The cylinder is made smooth
inside by being bored out and is usually
ground to size with a grinding wheel.
The inside diameter of the cylinder is
spoken of as the bore of the engine.
cooum
. WH7W SfiA££
Fio. 26. — Continental Model N auto-
mobile engine.
oo
Concentric piston ring. Eccentric piston ring.
Fio. 27. — Types of piston rings.
17. Pistons and Piston Rings. — The pistons which receive the force
of the explosion and expansion and transmit the motion to the connecting
rod and crank are commonly made of soft grey cast iron, although some
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THE AUTOMOBILE ENGINE
23
pistons of aluminum and also of an aluminum alloy called lynite are
being used. The aluminum and alloy pistons have the advantage of
being light, and it is also claimed that they radiate heat much faster than
cast iron. Being lighter than cast iron, the aluminum or alloy piston is
easier to move up and down in the cylinder. The expansion of these
pistons is more than for cast iron and, consequently, a greater clearance
must be provided when being fitted to the cylinders.
The pistons are turned and ground so that they will be a few thou-
sandths of an inch smaller in diameter than the cylinder in order that there
will be a good sliding fit without undue friction. The pistons are made
Fiq. 28. — Types of piston rings and ring joints.
gas tight by means of cast-iron piston rings placed in grooves around the
body of the piston. Ordinarily, three rings, placed in the piston above
the wrist pin, are used. In some cases an oil groove is also cut in the
piston below the rings to improve the lubrication between the piston
and the cylinder walls.
Piston rings are of two general types, the concentric and eccentric,
the difference being shown in Fig. 27. The concentric rings are of uni-
form thickness, while the eccentric rings are considerably thicker on the
side opposite the opening. It is impossible with a concentric ring to
get a uniform bearing pressure between ring and cylinder wall, but with
an eccentric ring, this is accomplished. In addition to these types of
one piece rings, numerous patented and two piece rings have been devised
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THE GASOLINE AUTOMOBILE
so as to get the advantages both of the concentric and eccentric types.
Figure 28 illustrates several types of these patented piston rings and also
several piston ring joints.
The pistons used in automobile engines are of the trunk type, explo-
sions taking place on one end only. The other end is open and allows
for the movement of the connecting rod. The length of the piston is
usually 134 times the diameter. The head of the piston is commonly
made flat, although occasionally pistons with slightly concave or convex
heads are used.
18. Connecting Rods. — The connecting rod may be either a forging or
a steel casting and may be either solid or of I-beam section as shown in
CAP
BEARING
Fig. 29. — Piston, connecting rod and parts.
Fig. 29. The connecting rod is under compression at all times and the
I-beam section is the best for withstanding the tendency of the rod to
bend. The connecting rod is attached to the piston by means of a steel
wrist pin. This pin may be clamped either to the connecting rod end
and turn on a bearing in the piston, or it may be clamped to the piston
bosses and the connecting rod turn on the fixed pin as in Fig. 25. The
bearing in the small end of the connecting rod is usually a bronze bush-
ing forced into the rod and then bored or reamed to size. The wrist pin
is usually made hollow in order to reduce the weight and to increase the
outside bearing surface.
The lower end of the connecting rod turns on the crankshaft. One-
half of the bearing is generally found in the rod itself, the other half being
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THE AUTOMOBILE ENGINE 25
held and supported by the cap which is bolted to the rod. By adjusting
these bolts, the wear on the bearing can be taken up from time to time.
The shims are very thin pieces which are placed between the halves of the
connecting rod bearing when the halves are tightened together by the
bolts. As the bearing wears it may be taken up by removing some of the
shims and then tightening the bolts. The bearing on the lower end of
the connecting rod may be entirely of bronze or may be a babbitted
bearing backed up by bronze. The babbitted bearing is much softer
than the bronze and is much easier to fit. It wears more quickly than
a bronze bearing and, consequently, needs to be adjusted oftener. Al-
though the bronze bearing is more difficult to fit, it wears longer and
needs less attention. Either type of bearing must have a little side play
on the crank pin in order to prevent heating. The length of the con-
necting rod is from 2 to 2*4 times the stroke of the engine. It is
desirable to have it as long as possible.
19. The Crankshaft — The crankshaft turns the reciprocating motion
of the piston and connecting rod into a circular motion. The length of
crank or the distance from the center of the crank pin to the center of
the main bearing is one-half the stroke of the piston, the stroke being the
distance the piston moves in one direction in the cylinder. A long stroke
engine is one on which the stroke is over 1% times the cylinder bore.
The longer the piston stroke is, the longer the engine crank must be.
When the crankshaft is running at high speeds, there are unbalanced
forces set up and these tend to shake and jar the engine. To prevent
this, many schemes have been devised for balancing these forces when
running. These will be taken up under multi-cylinder crankshafts.
20. The Flywheel. — The purpose of the flywheel is to keep the engine
running from one power stroke to another. In a single cylinder engine,
power is being delivered by the piston and connecting rod only about one-
quarter of the time. Part of this power is stored in the flywheel and
given back to the crankshaft and piston, during the other three-quarters
of the time. It can easily be seen that a single cylinder engine requires a
heavier flywheel than a four-cylinder engine of the same cylinder size.
As the number of cylinders is increased, the weight and size of the flywheel
can be reduced. In a great many automobile engines the flywheel and
clutch are built together as a small unit.*
21. Valves. — It is necessary in a four-stroke gas engine that provision
be made for getting fresh gases into the cylinder and for getting the burnt
gases out. This is done by the use of valves, two of which are provided
for each cylinder. One of these, the intake valve, provides the opening
for getting the gases in and the other, the exhaust valve, provides the
exhaust opening from the cylinder. In Fig. 25, the intake and exhaust
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THE GASOLINE AUTOMOBILE
valves with the operating mechanism are illustrated. An end view of a
similar mechahism is shown in Fig. 26.
The prevailing type of valve is called the poppet mushroom valve —
poppet from its operation, and mushroom from its shape. The valve
seat upon which the valve closes is generally found in the cylinder casting
Fig. 30. — Forms of poppet mushroom valves.
itself, although removable valve cages which carry the seat are sometimes
used. The common forms of valves are shown in Fig. 30.
The best materials for valve heads are cast iron, nickel steel, and
tungsten steel. Cast iron is very cheap, easily worked, and stands corro-
sion well. It is weak, however, and a heavier weight is, therefore, required
than with other materials. This weight is especially objectionable for
Cast iron.
B
Fia. 31. — Effect of pitting on tungsten and cast-iron valves.
high speed engines. Nickel steel is strong, non-corrosive, and has a very
low coefficient of heat expansion. Hence, it does not warp so readily as
other metals. It is rather expensive and when used is generally electri-
cally welded to a carbon-steel valve stem. Tungsten steel is very hard
and will stand high temperatures without pitting. Figure 31 shows the
relative effect of pitting on a cast-iron valve and a tungsten steel valve
after the same use on an engine. The tungsten valve has a smooth,
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THE AUTOMOBILE ENGINE 27
tight seat, while the cast-iron valve seat is pitted and worn. Cast-iron
valve heads can be screwed on a steel stem as in Fig. 30J?, the stem being
riveted to prevent loosening. Figure 30C shows a common European
form for valves which is being rapidly adopted here. The curvature
underneath gives the gases a smooth passage without any of the whirling
eddies that occur under the ordinary valve.
The valve seats are usually beveled at an angle of 45°, as shown,
though flat valves with flat seats are occasionally used. The valves must
be large enough to let the gases in and out of the cylinders freely. If
they are too small they will cut down the power of the engine by not
permitting it to get a full charge. The valves usually measure from one-
third to one-half of the cylinder diameter. Valve diameters are usually
measured by the opening in the valve seat (see dimension marked d in
Fig. 30.4). The diameter of the inlet and exhaust pipes should at least
equal this valve diameter and should be larger if possible.
The valve lift, or the distance the valve opens, should, when possible,
be sufficient to give the gases as large a passage between the valve and
seat as they have through the opening d, Fig. 30A. For a flat valve seat
this would require a lift of one-fourth of the valve diameter. With a
beveled seat, the gases pass through an opening in the shape of a conical
ring having a width of passage equal to A, Fig. 30A. To have the neces-
sary passage area, the lift h of the valve should be about three-tenths of
the diameter. In most stationary engines this lift can be given the valve,
but in high-speed automobile engines it would be too noisy. This lift
would cause pounding and wear on the cams. It would require very stiff
springs to make the valves follow the cams in closing and would be very
hard on the valve seats and stems. For automobile engines the valves
are made as large as possible and the lift is limited to from *Ke to ^ in.
Any valve needs regrinding into its seat occasionally with oil and
emery or ground glass. Exhaust valves require this more often than
inlet valves, as they become warped and pitted by the hot gases. After a
valve is ground in, the push rods should be readjusted, as the grinding
will lower the valve and reduce the clearance in the valve motion.
The engine in Fig. 26 has the valve seat on the engine casting and,
consequently, the valve and its seat cannot be removed for grinding.
With valves in the head, the valve and seat are built into a cage which
may be removed from the engine when it becomes necessary to grind the
valves.
22. Valve Operating Mechanism. — The form of mechanism for operat-
ing the valves depends somewhat on the valve arrangement. The valve
arrangement, in turn, is determined by the shape of the cylinder head.
The usual head arrangement, in turn, is determined by the shape of the
cylinder head. The usual head arrangements, illustrated in Fig. 32, are
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THE GASOLINE AUTOMOBILE
named from the shape of the combustion space and the cylinder. The
T-head permits of large valves and low lifts. It requires two valve
operating mechanisms and two camshafts, one on each side of the engine.
7=^
u
oJ
I-HeacL L-Head. T-Head.
Fig. 32. — Arrangement of valves on engine cylinders.
The L-head with both valves on one side requires only one camshaft.
The L-head does not present as much cooling surface to the combustion
chamber and is, therefore, a little more economical in fuel than the T-head
VALVES
CAM
FOLLOWERS
PLAIN
SPUR
* TIMING
GEARS
CAM
SHAFT
CRANK SHAFT
Fiq. 33. — Valve operating mechanism on Ford car.
arrangement. The l-head arrangement has come into quite popular use
because it gives a short, quick passage into the combustion chamber and
also a simple compact combustion chamber with a minimum loss of heat
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THE AUTOMOBILE ENGINE 29
to the cooling water. The valve in the head arrangement requires that
the motion of the push rod be reversed in order to operate the valves
properly. This is accomplished by means of a rocker arm. Both valves
are operated by one camshaft. With a T- or an L-head valve arrange-
ment, the operation of the valves is simplified.
The valves are operated as illustrated in Fig. 33 by two push rods,
one for each valve. These push rods receive their motion from the cams.
On the lower ends of these rods are rollers or followers, and these roll or
slide on the cams on the camshaft. These cams each have a hump or
projection on about one-fourth of their circumference. When one of
these strikes the roller or follower it raises it up, and this motion is trans-
mitted through the push rod to the valve. After the projection of the
cam has passed under the roller, the valve spring will close the valve
and force the push rod back to the original position. In order to allow
for expansion and to provide for certain adjustments in the opening and
closing of the valve, there is always a small clearance between the push
rod and its follower when the valve is on its seat.
23. Valve Opening and Closing. — The exhaust valve of an engine
opens on an average of about 45° before the end of the stroke, in order
that the pressure may be reduced to atmospheric by the end of the power
stroke, and also that there will be no back pressure during the exhaust
stroke following. At the end of the exhaust stroke, the exhaust valve
should remain open while the crank is passing the center so that any
pressure remaining in the cylinder may have time to be reduced to
atmospheric. The exhaust valve usually closes from 5° to 10° late
(past dead center), having been open from 230° to 235°.
The inlet valve very seldom opens before the exhaust closes. Most
manufacturers do not open the inlet until the exhaust closes, for fear of
back-firing, although there is little danger of this except with slow-
burning mixtures. The inlet valve opens, on an average, 10° late
(after center). At the end of the suction stroke there is still a slight
vacuum in the cylinder and the inlet is kept open for a few degrees past
center to allow this to fill up and get the greatest possible quantity of
gas into the cylinder. On an average, the inlet valve closes about 35°
late, depending on the piston speed of the engine. The inlet valve thus
remains open about 205°.
24. Half-time Gears. — Since the valves on an engine open and close
but once in two revolutions, the engine must be arranged so that the
cams on the camshaft come around and strike the cam followers only
once in two revolutions of the engine crank. To do this, the arrangement
is to put a gear on the crankshaft and have this drive another gear,
twice as large, on the camshaft. In this way the camshaft will run at
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THE GASOLINE AUTOMOBILE
just half the speed of the crankshaft. These gears are called half-time
gears.
Plain spur gears with straight teeth, or helical gears with teeth at
an angle, are the usual type of half-time gears. In some cases the posi-
tive connection between gears is furnished by a chain drive similar to
that on a bicycle. The plain spur timing gears, together with the cam-
shaft and valves on the Ford car, are shown in Fig. 33. The helical
timing gears in the Case engine are illustrated in Fig. 34 and the silent
chain drive in Fig. 35. Difficulty is sometimes experienced with the
plain spur gear on account of the
lost motion due to wear, and with
the chain drive due to an increase
in length . These difficulties have
to a large extent been overcome
by the use of the helical gears.
Fig. 34. — Helical timing gears.
Fio. 35. — Silent chain camshaft drive.
25. The Knight Engine. — The Knight engine is built on the principle
of the four-stroke cycle, but the usual poppet valves have been replaced,
by two concentric sleeves which slide up and down between the piston
and cylinder walls. Certain slots in these sleeves register with one an-
other at proper intervals, producing direct openings into the combustiQn
chamber from the exhaust and inlet ports. The construction of the
Willys-Knight motor is illustrated in Fig. 36, which shows the general
arrangement of the parts and their nomenclature.
It will be noted that the sleeves are independently operated by
small connecting rods working from an eccentric or small crankshaft
running lengthwise of the motor. This eccentric shaft is positively
driven by a silent chain at one-half the speed of the crankshaft. The
eccentric pin operating the inner sleeve is given a certain lead or advance
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THE AUTOMOBILE ENGINE
31
over the pin operating the outer sleeve. This lead, together with the
rotation of the eccentric shaft at half the crankshaft speed, produces the
valve action illustrated in Fig. 37, which shows the relative positions of
the pistons, sleeves, and cylinder ports at various points in the rotation
of the crankshaft.
The advantage of the sliding sleeves over the usual valve type is
that they are practically noiseless in operation. It is also possible to
Spark plug
Exhaust manifold
Intake manifold
Piston
Piston connecting rod
Crankshaft
Outer sleeve
Inner sleeve
Connecting rod, to
operate outer sleeve
Connecting rod, to
operate inner sleeve
Eccentric shaft
Fig. 36. — Cylinder on Willys-Knight engine.
have larger openings and ports into the cylinder, thereby insuring a full
charge of fuel to the cylinders at all engine speeds.
26. The Fuel Charge. — When the inlet valve opens, the suction of
the piston moving downward draws a charge of fuel into the cylinder. To
evaporate the gasoline and mix this gasoline vapor with the proper
amount of air is the function of the carburetor which is treated in detail
in one of the following chapters.
27. Ignition. — In order to cause the explosion within the cylinder,
some means must be provided for igniting the charge of gas. This is
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THE GASOLINE AUTOMOBILE
usually done by causing an electric spark to pass between two points
within the cylinders. This spark sets fire to the mixture and the ex-
plosion follows.
There are two general methods of electric ignition. One of these is
called the make-and-break system because it requires moving parts inside
v "H <
Intake stroke.
Intake ports open.
Exhaust ports closed.
Compression stroke.
All ports closed and sealed by ring
in cylinder head.
Power stroke.
All ports closed and protected by
ring in cylinder head.
Exhaust stroke.
Intake ports closed.
Exhaust ports open.
Fig. 37. — Valve events in Willys-Knight engine.
the cylinder to make an electric circuit, and then break it quickly so
that a spark will occur inside the cylinder. The other system is called
the jump-spark system. This is the system used in automobiles. In
this system there are no moving parts which have to pass through the
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THE AUTOMOBILE ENGINE 33
cylinder wall. The spark coil or magneto makes a current powerful
enough to jump between two fixed points inside the cylinder. The com-
plete details of these systems of ignition will be taken up in a later
chapter.
28. The Muffler. — When the exhaust valve of an engine opens at
the end of the expansion stroke the pressure of the gas inside the cylinder
is still about 50 or 60 lb. per square inch. The valve must open and
let this pressure out before the piston starts back, or else the back pres-
sure will tend to stop the engine. The valve is opened quickly, and
the high pressure, being suddenly released into the exhaust pipe, causes
the sharp sound which is heard when an engine exhausts. This sound is
not the sound of the explosion, as is commonly supposed. The real ex-
U-<u=L
^-^
^ W -—_ —
Fio. 38. — Typical muffler.
plosion takes place a little before this sound and can be heard only as
a dull thump inside the cylinder. The explosion occurs at the beginning
of the working stroke, while the sound that we hear in the exhaust comes
at the end of the stroke. In order to prevent this sudden exhaust from
causing too great a noise it is customary to have a muffler. A muffler,
Fig. 38, is a chamber in the exhaust pipe which receives the exhaust
gases from the engine an4 expands them gradually into the outside air,
thus preventing a loud noise. *
The use of a muffler causes a slight reduction in the power of the engine
because the pressure against which the gases must exhaust in the exhaust
manifold is increased. A cut-out which permits the exhaust gases to
expand directly into the air without going through the muffler can be
used wherever the noise is not objectionable nor the use of the cut-out
prohibited by law.
29. Cylinder Cooling. — When an explosion occurs inside the cylinder
of an engine, the gases on the inside reach a temperature somewhere
around 3000°. The walls of the cylinder are, of course, exposed to this
high heat and would get red hot very quickly if there was not some way
of keeping them cool. The polished surface upon which the piston
slides would be spoiled very quickly. The most common way of keeping
the cylinder cool is by the use of water. The arrangement for this is
shown on the engines illustrated in this chapter. Surrounding the cylin-
3
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34 THE GASOLINE AUTOMOBILE
der ia a jacket with a space between for the cooling water. By keeping a
supply of water passing through this space, the cylinder can be kept
cool enough for the operation of the engine. The cylinder head is also
cast with a double wall, especially around the valves, so that these parts
will also be kept cool. The cooling fluid used is generally water, although
sometimes special anti-freezing solutions are used where there is danger
of the engine freezing. Water should not be allowed to remain in the
jacket of an engine over night if there is danger of a frost, as the freezing
of the water will crack the cylinder. When the supply of water is limited,
as in an automobile, the water is cooled in a radiator or system of pipes,
and used over again. The water is kept in circulation by a pump or by
the thermosyphon system and the hot water cooled by the air passing
over the radiator.
30. Piston Displacement. — This refers to the space swept through by
the piston in going from one end of the stroke to the other. It is given
this name because, as the piston moves through its stroke, it will either
draw in or force out that volume of air or gas. The piston displacement
is calculated by multiplying the length of stroke by the area of a circle
whose/ diameter is the inside diameter of the cylinder. For example, a
3J^-in. by 5-in. engine (this means 3J^-in. inside cylinder diameter and
5-in. stroke) would have a piston displacement as follows:
The area of a 3^-in. circle is 0.7864 X 3}i X 3H = 9.621 sq. in.
The piston displacement is 5 times this, or 48.105 cu. in.
The clearance of such an engine would be from 24 to 30 per cent, of
this. If we suppose that it is 25 per cent., then the actual space which
must be left for the clearance will be 48.105 X 0.25 = 12.026 cu. in.
31. Clearance and Compression. — It was discovered by some of the
early inventors of gas engines that compressing a gaseous mixture causes
it to gftfe a much more powerful explosion. Consequently, all gas engines
draw in a full cylinder charge of gas and air, and then compress this
back into a space left at the upper or rear end of the cylinder. This
space, which is left for the gas to occupy when the piston is at the top
end of its stroke, is called the clearance space or combustion chamber.
The amount of this clearance space in relation to the whole cylinder
volume determines just how much the gas is compressed. It has been
found from experience that different kinds of gases require different
amounts of compression and, therefore, the clearance space is made
different for different fuels. The clearance is generally spoken of as
being a certain per cent of the piston displacement, varying from 24 to 30
per cent, for automobile engines.
32. Horse Power of Engines. — The horse power of an engine is the
measure of the rate at which it can do work. One horse power is a
rate of 33,000 ft.-lb. a minute. There are two ways of measuring engine
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THE AUTOMOBILE ENGINE 35
power. We can determine the power developed by the explosions in the
cylinder, in which case we have what is called the indicated horse power
(i.hp.) ; or we can attach a brake to the flywheel and measure the power
which the engine actually delivers. This is called the brake horse power
(b.hp.). Engines are usually rated by their brake horse power because
that is what they are actually capable of delivering. The brake horse
power of an automobile engine will usually be from 70 to 85 per cent, of
its indicated horse power, the loss being that consumed in the engine
mechanism.
There are a number of quick rules for estimating the power of engines
according to their cylinder dimensions and the speed. Those most used
for four-stroke engines are given below. The simplest of these and the
one most used is known as the S. A.E. formula or Society of Automotive
Engineers formula.
33. Derivation of the S.A.E. Horse Power Formula. — The indicated
horse power of a single-cylinder, four-stroke engine is equal to the mean
effective pressure, P, acting throughout the working stroke, times the
area of the piston, A, in square inches, times one-quarter the piston speed,
S, divided by 33,000, thus:
PAS
thp' 33,000 X 4
Multiplying this by the number of cylinders, N, gives the indicated
horse power for an engine of the given number of cylinders, and further
multiplying by the mechanical efficiency of the engine, E} gives the brake
horse power.
Therefore, the complete equation for brake horse power reads:
PASNE
b.hp. =
33,000 X 4
The S.A.E. formula assumes that all motor car engines will deliver
or should deliver their rated power at a piston speed of 1000 ft. per
minute; that the mean effective pressure in such engine cylinders will
average 90 lb. per square inch; and that the mechanical efficiency will
r<- average 75 per cent.
Substituting these values in the above brake horse power equation,
and substituting for A its equivalent, 0.7854D2, the equation reads:
90 X 0.7854D2 X 1000 XNX 0.75
bMp'~ 33,000X4
and combining the numerical values it reduces to:
b.hp. =
2.489
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36 THE GASOLINE AUTOMOBILE
To make it simpler, the denominator has been changed to 2.5 without
materially changing the results.
The formula can be simplified, however, for ordinary use by consider-
ing the number of cylinders; thus for the usual four-, six-, and eight-
cylinder engines it becomes:
1.6 D1 = hp. for all four-cylinder motors.
2.4 D* = hp. for all six-cylinder motors.
3.2 D* = hp. for all eight-cylinder motors.
4.8 D* = hp. for all twelve-cylinder motors.
The S.A.E. formula comes very close to the actual horse power de-
livered by most automobile engines at the piston speed of 1000 ft. per
minute. However, at the present time, most of the engines will deliver
the maximum power at speeds higher than this, usually around 1500
ft. per minute. As a result, the power which the engines are capable
of delivering is greater than that given by the S.A.E. formula. The
formula will serve, however, as a means of comparing engines on a uniform
basis.
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CHAPTER III
AUTOMOBILE POWER PLANTS
34. Multi-cylinder Engines. — The first automobile power plant con-
sisted of a one-cylinder engine which gave power impulses at regular
intervals of time for the propulsion of the car. Naturally it operated in
a jerky manner and with considerable noise, due to the size of the cylinder
and the time between power impulses. These disadvantages led to the
lCyhakc
2GjrUndflr»
4 Cylinders
6Cyttod«rt
Ijjllllllljllll
1 iil
if
1
mil
«Cy Undid
Fig. 39. — Power diagrams.
adoption of the two-, four-, and six-cylinder engines; and even the eight-
and twelve-cylinder engines have come into general use as automobile
power plants.
In Fig. 39 can be seen one of the distinct advantages of the multi-
cylinder engine for motor car purposes. The length of the diagram rep-
37
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38 THE GASOLINE AUTOMOBILE
resents two revolutions of the engine crankshaft or one complete cycle
of the engine. The curved line acefg represents the variations in the
power from a single cylinder. The line bh represents uniform power
requirement of the car. When the power curve goes above bh the engine
speeds up and the surplus power is thus stored in the flywheel; when the
curve goes below bh the flywheel gives up power and the engine slows
down.
As the number of cylinders increases, the power impulses increase
in frequency, the average power is greater, and above four cylinders there
is no period during which some cylinder is not delivering power. This
means that in a six-, eight-, or twelve-cylinder car, there is no time during
which the flywheel must supply all the power required by the car.
The multi-cylinder engine, therefore, furnishes practically a con-
tinuous flow of power to the car with little vibration. The increase in
the number of cylinders has a tendency to reduce the size of each cylinder
and this combined with the steady operation of the engine, makes the
automobile engine a very quiet, smooth running, power plant unit.
35. Modern Automobile Power Plants. — The automobile power
plant includes the engine and all auxiliaries necessary for the production
of power. The transmission system includes the mechanism necessary
for taking that power furnished by the engine and transmitting it to
the rear wheels. In most cases, the power plant includes the engine and
its component parts such as the carburetor; starting, lighting, and
ignition equipment; cooling and lubricating systems; etc. When the
unit power plant is used, it includes, in addition to the engine and its
essential component parts, the clutch and the change gears.
It should be understood that in the case of a four-cycle engine, all
the cylinders must fire in two complete revolutions of the crankshaft
regardless of the number of cylinders. For example, in a four-cylinder
engine there are two power impulses per revolution of the crankshaft,
while in an eight- or twelve-cylinder engine, there are four or six power
impulses per revolution, respectively.
The use of the four-cylinder engine as an automobile power plant
has been slowly giving away in part with the adoption of the engine with
six, eight, and twelve cylinders. In general, the gasoline consumption
per unit of power increases with the number of cylinders, so from the
standpoint of fuel consumption alone, the four-cylinder engine has the
advantage. Due to the increased number of power impulses per revolu-
tion, the six-cylinder engine gives a much better balance to the crankshaft,
thereby cutting down the vibration on the car. The car equipped with
a six-, eight-, or twelve-cylinder engine is more flexible in operation and
can be run under all conditions with less frequent changing of gears.
The four- and six-cylinder engines are built with cylinders vertical,
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AUTOMOBILE POWER PLANTS 39
while the eight-cylinder engine consists of two blocks of four cylinders
each, placed in the form of a V with an angle of 90°. The crankshaft is
essentially the same as used for a four-cylinder engine. In the twelve-
cylinder engine, the angle of the V is 60°, the crankshaft being like that
of the six-cylinder engine. As a general rule, the bore of the cylinders in
the eight and twelve is less than in the four and six. The power impulses
come closer together giving a smoother running and more flexible engine*
In numbering the pistons or cylinders of a four- or six-cylinder engine,
the first or number one cylinder is the one next to the radiator or the
front of the engine.
36. Power Plant Support — The power plant of an automobile is
placed near the front and is supported by the frame of the car. The
engine crank case is designed so that it is supported on the frame at
four points or is designed to be supported at only three points. When
three point support is used, the engine is carried on the frame by one
point at the front and two at the back, or by two points at the front and
one at the back. The three point support has the distinct advantage
that no strain or stress will be thrown on the engine shaft or bearings,
if the side of the car frame be twisted or sprung. In some cases a sub-
frame built inside of the main car frame serves to carry the power plant
of the car.
37. Four-cylinder Power Plants. — The Dodge four-cylinder engine,
Fig. 40, shows the cylinders cast en bloc with the cylinder head removable.
The block casting permits a short, compact, and rigid engine. Although
it is cheaper in the first cost, the cost of replacing in case of a damaged
cylinder is higher than with cylinders cast singly or in pairs. The
cylinder diameter is 3% in. and the stroke 4J£ in. The piston displace-
ment is 212 cu. in. The engine is rated at 24 horse power.
The L-head valve arrangement is shown with both inlet and exhaust
valves operated by one camshaft. .The camshaft which is made with
the cams solid on the shaft is driven by helical gears, which prevent the
backlash or lost motion which is sometimes found when plain spur gears
are used.
The pistons are of cast iron and are fitted with three rings above the
wrist pin. The connecting rod is of I-section. At its upper end its
bearing is on the hollow wrist pin which is prevented from turning in
the piston bosses by means of the cap screw shown. The crankshaft has
the conventional three main bearings.
38. Ford Power Plant. — The Ford unit power plant with three point
support is shown in section in Fig. 41, with all parts fully designated.
The cylinders with the water jackets and upper half of the crank case
are cast en bloc. The cylinder head being removable permits easy access
to the cylinders and valves. The crankshaft, camshaft, and the con-
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THE GASOLINE AUTOMOBILE
necting rods are made from a special vanadium steel permitting a light
construction which at the same time retains its strength. The piston
has three rings, two near the top and one at the bottom. The crankshaft
has the customary three main bearings. The camshaft is driven by plain
spur gears, as indicated. The magneto, transmission gears, and clutch-
ing arrangement are of considerable interest and will be discussed later
under the proper headings. The cylinders are 3% in. by 4 in., and the
engine is rated at 22.5 horse power.
39. White Four-cylinder Engine. — The four-cylinder engine used in
the Wliite car presents some extraordinary features as may be seen from
REHQVABLE CYLINDER
HEAD
WATER COOLING
WRIST PIN, SPACE, PISTON /
iNTAKE VALVE*
EXHAUST VALVE
VALVE SPRINGS?
FLYWHEEL
-CAM SHAFT
tlAIN BEARING
Fig. 40. — Dodge four-cylinder engine.
Figs. 42 and 43. Instead of only one intake and one exhaust valve for
each cylinder, two are provided. This arrangement gives an unusually
large and desirable area for getting the gases into and out of the cylinders
quickly. The T-head valve arrangement requires the use of two cam-
shafts which are driven by helical gears.
The cylinder size is comparatively large for a four-cylinder engine,
434 in- by b% in. When an engine with a large cylinder is run at high
speed and, consequently, high ' piston speed, it is often impossible for a
full charge of gas to get into the cylinder. This cuts down the power and
efficiency. With the exceptionally large valve area provided by double
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AUTOMOBILE POWER PLANTS
41
In ml hi
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42
THE GASOLINE AUTOMOBILE
Fia. 42. — Top view of cylinders and valves on White 16 valve four-cylinder engine.
Fio. 4&. — Crank case and camshafts on White 16 valve four-cylinder engine.
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AUTOMOBILE POWER PLANTS
43
valves, the large cylinders can be run at high speed without cutting down
the charge of gas to the cylinders.
40. Duesenberg Engine. — The Duesenberg automobile engine, Fig.
44, is provided with horizontal valves which are placed in the cylinder
head. These valves are operated by a side lever which transmits the
motion directly from the cam. The horse power varies from 35 at 1000
r.p.m. to 80 at 2100 r.p.m. The weight of this motor is about 490 lb.
The piston carries one piston ring of triple construction. The connect-
ing rods are of I-section and are clamped to the piston pins, the bearing
being in the piston bosses. The crankshaft has only two main bearings.
Fio. 44. — Duesenberg four-cylinder engine.
The cylinders are cast en bloc, an unusually large cooling space being
provided. This engine being of the high-speed type is commonly used
for racing purposes.
41. Guy Rotary Valve Engine. — The rotary valves of the Guy engine
used on the Hackett car are illustrated in Figs. 45 and 46. These rotary
valves are driven by spur gears which in turn are driven by one small
master gear. The valves rotate at one-eighth crankshaft speed and give
four intake openings and four exhaust passages for each of the four cylin-
ders. The special claim made for this type of valve is that it provides an
unusually large valve opening while giving all the advantages of a valve
in the head engine.
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THE GASOLINE AUTOMOBILE
42. Six-cylinder Power Plants. — The Case six-cylinder power plant
is shown in Fig. 47. The cylinders are of the L-head type cast en bloc.
The push rods and tapered valve springs can be clearly seen. The cam-
shaft is driven from the crankshaft by helical, gears. The small helical
gear at the left drives the centrifugal pump which circulates the cooling
Fio. 45. — Top view of cylinders showiDg rotary valves.
water, and also the generator which furnishes the current for charging the
batteries and for ignition. The water jacket is cast integral with the
cylinder casting. The cylinder head is not removable but is cast with
the cylinders. The horse power is approximately 30 and the cylinders
are 3J^-in. bore by 5J4-i&- stroke.
Fio. 46. — Bottom view of cyliDder head for rotary valve engine.
43. Marmon Power Plant. — The Marmon power plant shown in
Fig. 48 is characterized by the extensive use of aluminum in its construc-
tion. The upper half of the crank case, the cylinder retainers, and the
water jackets are cast in one piece of aluminum as illustrated in Fig. 49.
The cylinder sleeves, Fig. 50, are separate, being made of cast iron and set
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AUTOMOBILE POWER PLANTS
45
Fig. 47.— Case continental six engine.
Fig. 48. — Marmon six-cylinder power plant.
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46
THE GASOLINE AUTOMOBILE
into the aluminum retainers. The cylinder head or firing head is of cast
iron and is bolted to the top of the aluminum cylinder casting. The
Fiq. 49. — Aluminum cylinder casting on Marmon engine.
Fig. 50. — Removable cylinder liners on Marmon engine.
valves are placed in the head and are operated by overhead valve rocker
arms. An aluminum cover fastens over the valve mechanism. The
total weight of the engine with the aluminum castings is about 650 lb.
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AUTOMOBILE POWER PLANTS
47
The cylinders are 3%-in. bore and 5j^-in. stroke. The pistons of cast
aluminum alloy parry four piston rings as shown. The bottom ring serves
as an oil wiper.
44. Franklin Air Cooled Engine. — The Franklin engine, Fig. 51,
represents a very interesting and unique design, having overhead valves
Overhead-
va/ves
Fig. 51. — The Franklin air-cooled engine.
and air cooling. The cylinders are cast singly and each is air cooled by
a system of cast ribs, doing away with the water jackets around the
cylinders. The air is drawn downward around the cylinder ribs by the
suction of the flywheel fan.
Fig. 52. — Hall-Scott aviation type automobile engine.
46. The Hall-Scott Engine. — The Hall-Scott aviation type engine,
Figs. 52 and 53, has the cylinders cast singly of grey and Swedish iron.
The valves are operated by an overhead camshaft, as indicated. Special
attention has been given to cooling this engine as it has been designed for
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THE GASOLINE AUTOMOBILE
high powers and speeds. The weight is 565 lb. and gives 125 horse power
at 1300 r.p.m. The cylinders are 5-in. bore and 7-in. stroke.
46. Chandler Six Power Plant. — The casting of engine cylinders in
pairs of three is illustrated on the Chandler engine, Fig. 54. This engine
is of the Lr-head type. The camshaft is driven by means of a silent chain.
This type of camshaft drive is not so positive as a gear drive. Any play
due to wear, etc. must be taken up
immediately in order to keep the
valves in time.
47. Constructional Features of
Four- and Six-cylinder Engines. —
The essential differences of construc-
tion on the various four- and six-cylin-
der engines, outside of the methods
of cylinder construction and valve ar-
rangement, consist mostly in the con-
struction and arrangement of the cam-
and crankshafts. Figure 55 is a con-
ventional four-cylinder crankshaft,
shown with connecting rods and pis-
tons attached. No attempt has been
made to counterbalance this shaft.
There are three main bearings, as in-
dicated. As is customary in a four-
cylinder engine, the connecting rod
bearings are all in the same plane,
bearing Nos. 1 and 4, the two end
bearings, being just 180° from Nos. 2
and 3, the two center bearings. This
means that the No. 1 piston and the
No. 4 piston are in the same position
in the cylinders at the same time.
Likewise, No. 2 and No. 3 are in the
same position. If No. 1 piston is on
the compression stroke, No. 4 must necessarily be on the exhaust stroke
and Nos. 2 and 3 on the suction and explosion strokes. On account
of the arrangement of the cranks on the shaft, the order of firing in a
four-cylinder engine must be in the order 1, 3, 4, 2, or 1, 2, 4, 3.
On account of the fact that a crankshaft, such as shown in Fig. 55,
is very unbalanced and produces excessive vibration on the engine and
car, many methods of counterbalancing four-cylinder crankshafts are in
use. In the crankshaft shown in Fig. 56, counterweights have been
placed opposite the crank bearings to overcome the unbalanced forces.
Fig.
53. — Section of Hall-Scott aviation
type automobile engine.
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AUTOMOBILE POWER PLANTS
49
Only one counterweight is used for two center cranks. Another method
of attaching the counterweights is shown in Fig. 57. Two sets of weights
serve to counterbalance the entire shaft.
Cooung WVre«
OuTltT
SlLlNT
.Chain
Drives*
Fig. 54. — Chandler six-cylinder engine.
4/ 'b
Fig. 55. — Three-bearing, four-cylinder crankshaft.
The conventional four-cylinder crankshaft has three main bearings
as in Fig. 55. The center bearing does away with the tendency of the
shaft to spring. In some cases, as in Fig. 56, only two main bearings
4
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50
THE GASOLINE AUTOMOBILE
are used. The crankshafts are made in one piece, although when it is
desired to use ball bearings on the crank and main bearings, the shaft is
built up. This practice, however, is rare.
48, Six-cylinder Crankshafts. — There are two ways in which cranks
on a six-cylinder crankshaft are arranged. The sketches in Fig. 58 show
this essential difference. Starting with crank 1 up, as shown, crank
2 may be either 120° to the right or left. Crank 3 is then 120° beyond
crank 2. In either case, cranks 1 and 6, 2 and 5, 3 and 4 are in the same
■=4/ty=$
Flo. 56. — Four-cylinder counterbalanced crankshaft.
plane and in similar positions. A crankshaft is either right or left, de-
pending upon whether cranks 3 and 4 are 120° to the right or left of cranks
1 and 6, when the latter af e vertical. Figure 58-4 represents a right crank
and Fig. 582? a left crank, the flywheel being at the far end of the shaft.
As each cylinder fires once in two revolutions of the crankshaft, there
are, consequently, three explosions per revolution or one every one-third
revolution of a six-cylinder crank.
Ordinarily, a six-cylinder crankshaft has three main bearings as in
Fig. 59. In some cases, four main bearings, as shown in Fig. 60, may be
hSmJf*
Fig. 57. — Counterbalance weights on a four-cylinder crankshaft.
used, or seven as in the case of the Hall-Scott airplane engine, the crank-
shaft of which is illustrated in Fig. 61. Only in rare cases has a six-
cylinder crank been constructed with two main bearings. Without
one or more center bearings the shaft would spring unless it were made
unusually heavy and strong.
The six-cylinder crankshaft, on account of the number and arrange-
ment of the cranks, is naturally much better balanced than a four-
cylinder crankshaft. The power impulses come oftener; consequently,
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AUTOMOBILE POWER PLANTS
51
l?e \
A^>
e*5 5*4
A
3*4 2+S 8
Flo. 58. — Methods of crank arrangement for six-cylinder engine.
Flo. 69. — Chandler six-cylinder crankshaft with three main bearings.
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52
THE GASOLINE AUTOMOBILE
the unbalanced forces are not so evident. By the proper distribution of
the weight, it is possible to give a fairly well balanced crankshaft without
the addition of counterbalance weights.
The crank shown in Fig. 59 is a right crank while that in Fig. 61 is a
left crank. The only essential difference is that in one case the flywheel
is on one end of the crank, while in the other it is placed on the opposite
FLYWHCO. PISTON «!N«
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Fio. 60. — Four-bearing, six-cylinder crankshaft.
end. The crank arrangement determines the order in which the cylinder
can fire; assuming that the direction of rotation is the same in each case.
Referring to Fig. 58 A, the crank arrangements for the crank of Fig. 59
are seen. Obviously, pistons 1 and 6, 2 and 5, and 3 and 4 will be in the
same respective positions in their cylinders at the same time. If pistons
1, 2, or 3 are on the suction stroke, then pistons 6, 5, or 4 will be on the
Fio. 61. — Hall-Scott crank case with seven main bearings.
expansion stroke. If i, 2, or 3 are on the compression, then 6, 5, or 4
will be on the exhaust. It is also evident that the cylinders can fire only
in certain definite orders. For instance, the right crank in Fig. 5SA
might fire 1, 5, 3, 6, 2, 4, or 1, 2, 3, 6, 5, 4, or 1, 5, 4, 6, 2, 3, or 1, 2, 4„6,
5, 3. The first order given, 1, 5, 3, 6, 2, 4, is the b^st and most usual
firing order, because the power impulses are better distributed along the
crank.
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AUTOMOBILE POWER PLANTS
53
The left crank, Fig. 58B, corresponds to the crank positions shown in
Fig. 61. The firing order might be 1, 3, 5, 6, 4, 2, or 1, 4, 5, 6, 3, 2, or
1, 3, 2, 6, 4, 5, or 1, 4, 2, 6, 3, 5. The last order, 1, 4, 2, 6, 3, 5, is the best
order for the reason given above.
49. Camshafts. — In Figs. 62 and 63 are illustrated the two general
methods of camshaft construction. Figure 62 is a one-piece camshaft,
the cams and shaft being made of one solid bar of steel. This is the more
common method of construction. The assembled camshaft, Fig. 63, on
which the individual cams are pinned or keyed, is used at present in very
Fio. 62. — One-piece camshaft.
few cases. The objection to this type of shaft is that the cams may
become loose on the shaft and give considerable trouble. It has the
advantage that the cams can be replaced after considerable wear. For
an L-head engine, a single camshaft on one side of the engine carries both
inlet and exhaust cams. For a T-head engine, however, one camshaft
carries the inlet cams on one side of the engine and another shaft carries
the exhaust cams on the other side.
The camshafts are driven at one-half crankshaft speed. The drive
may be either by a silent chain, such as shown on the Chandler, Fig. 54,
Assembled camshaft.
by spur gears, such as on the Ford, Fig. 41, or by helical gears, such as on
the Case engine shown in Fig. 47.
60. Eight- and Twelve-cylinder Power Plants. — In the four-cylinder
engine there is a power impulse every one-half revolution, but during a
small interval at the end of each power stroke, no power is being delivered
by the engine. This means short periods in the operation of the engine
in which the flywheel must supply all the power. In the six-cylinder
engine, there is a power stroke every one-third revolution and, as a result,
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54
THE GASOLINE AUTOMOBILE
there is an overlapping and a more continuous flow of power, Fig. 39.
The power impulses come oftener and, consequently, the vibration is
reduced. The same effect is carried further in the eight-cylinder engine
which gives a power stroke every one-fourth revolution and in the twelve-
cylinder engine where the power strokes come one-sixth of a revolution
apart. The parts are considerably lighter and this aids in reducing the
vibration. The eight- and twelve-cylinder engines are built in the V-type.
This method of construction adds to the smoothness of operation.
51. Cadillac Eight-cylinder Engine. — Figure 64 is a front end view
of the Cadillac eight-cylinder engine. The cylinders are arranged in
blocks of four each, placed in a V-shape at an angle of 90°. A cross
Pio. 64. — Cadillac eight-cylinder engine. r
section of two opposite cylinders is shown in Fig. 65. The engine is of
the L-head type with the valves on the inside of the V. The cylinder
heads are removable, permitting access to the valves. One camshaft
placed directly above the crankshaft operates all of the sixteen valves
by means of the rockers as shown. Eight cams serve to operate the six-
teen valves, as one cam operates a valve in each cylinder block. The
camshaft is carried by five bearings and has a silent chain drive as shown
in Fig. 64.
The crankshaft is like a conventional four-cylinder shaft with three
main bearings. There are only four crank pins, and two connecting rods,
one from each side of the engine, bearing on the same crank, Fig. 66.
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AUTOMOBILE POWER PLANTS
55
One of the rods, Fig. 67, is forked, while the other is perfectly straight,
fitting in between the forks of the other. The split bearing shown at the
*yj^
j£«?
m
Fia. 65. — Sectional view of Cadillac eight-cylinder engine.
right fits directly over the pin. The forked rod fits over this bearing
and is pinned to it so that the rod and bearing work together. The other
Fig. 66. — Cadillac crankshaft, piston, and connecting rod assembly.
rod fits over the center surface of the bearing and runs on it. This
arrangement permits the length of the crankshaft to be no greater than
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56
THE GASOLINE AUTOMOBILE
in a four-cylinder engine. On some eight-cylinder engines, one cylinder
block is sometimes set ahead of the other so that the connecting rods
from opposite cylinders can turn side by side on the same crank pin.
Fiq. 67. — A pair of Cadillac connecting rods.
The horse power rating of the Cadillac eight is 31.25 according to the
S.A.E. formula. On dynamometer test, however, it has developed 70
horse power at a speed of 2400 r.p.m.
52. The Oldsmobile Eight-cylinder Engine. — The cylinder block
castings of the Oldsmobile eight-cylinder engine are shown in Fig. 68.
Fio. 68. — Cylinder blocks of Oldsmobile eight-cylinder engine.
The cylinder heads are cast separately and made removable for inspec-
tion of the valves and the inside of the cylinders. The two cylinder
blocks are clamped together by bolts, giving a very compact and sturdy
construction. The connecting rods, Fig. 69, are arranged in pairs, one
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AUTOMOBILE POWER PLANTS
57
rod of each pair being straight and the other forked as shown. Both
rods fit on the bearing shown. This bearing is of bronze, lined on the
inside with babbitt. The crankshaft is of the four-cylinder type with
only two main bearings.
Fio. 69. — Oldsmobile connecting rods and crankshaft.
63. King Eight-cylinder Engine. — In the King eight-cylinder engine,
Figs. 70 and 71, the cylinder blocks are staggered, the left block being
slightly ahead of the right one so as to permit the use of straight connect-
Fia. 70. — King eight-cylinder engine.
ing rods, turning side by side on the same crank pin as indicated. The
cylinder and heads are cast in one piece, caps being provided for removing
the valves, which are inclined to the cylinder as indicated. The sixteen
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THE GASOLINE AUTOMOBILE
valves are operated by a single camshaft driven by a silent chain. The
camshaft is of the solid type with the sixteen cams integral with the shaft.
The crankshaft has three main bearings which are unusually long. It
is hollow so as to provide forced lubrication to all crank and main bearings.
54. Knight Eight-cylinder Engine. — The Knight engine is also built
in the eight-cylinder type as shown in Fig. 72. The sliding sleeves are
operated by small connecting rods which turn on a small crank or cam-
shaft. The use of the sliding sleeves gives the advantages of a valve in
the head motor, at the same time using eight cylinders. The intake
parts are inside of the V, and the exhaust parts on the outside lead to
separate exhaust pipes. The combination of the sliding sleeves and the
Fiq. 71. — Sectioned view of King eight-cylinder engine.
eight cylinders gives an exceptionally smooth running engine with very
little vibration.
55. Firing Order of Eight-cylinder Engines. — The cylinders of an
eight-cylinder engine are generally numbered as shown in Fig. 73, the
right and left blocks being numbered from the radiator to the back. The
possible firing orders of each block are the same as in a four-cylinder
engine. It will be noticed that on account of the cylinder blocks being
placed at an angle of 90°, that when the pistons of cylinders XL and AL
are at the top of the stroke, pistons 2L and 3L are at the bottom of the
stroke and all the pistons of the right block are at the middle of the
stroke, two of them moving towards the top and the other two towards
the bottom. This means that the power impulses will be 90° apart, and
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AUTOMOBILE POWER PLANTS
59
that the firing will alternate from one side to the other. Although it is
possible to have four firing orders for an eight-cylinder engine, two of these
Fig. 72. — Eight-cylinder Knight type engine.
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Fio. 73. — Methods of numbering the cylinders on an eight-cylinder engine.
are practically never used. Both cylinder blocks usually fire in the
1, 3, 4, 2 order or the 1, 2, 4, 3 order. If in the 1, 3, 4, 2 order, the firing
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60 THE GASOLINE AUTOMOBILE
order for the engine is 1L, 2ft, 3L, lft, 4L, 3ft, 2L, 4ft, as shown on Fig.
73 A. If the 1, 2, 4, 3 order is used the engine fires LL, 3ft, 2L, lft, 4L,
2ft, 3L, 4ft, as on Fig. 734.
The system of numbering the cylinders is not always as shown in
Fig. 73ii. The cylinders may be numbered in the order of firing as on
the Cadillac, Fig. 73B, or as on the Cole car, Fig. 73C, where the cylinders
are numbered 1, 2, 3, 4, on the right side, beginning at the radiator, and
5, 6, 7, 8, on the left side, also beginning at the radiator. The order of
firing on the Cadillac corresponds to the order previously given, LL, 2R,
3L, lft, 4L, 3ft, 2L, 4ft. The firing order on the Cole is 1, 8, 3, 6, 4, 5, 2,
7, as in Fig. 73C, which is the same order as on the Cadillac. The num-
bering and order of firing on the Oldsmobile, and King eight are the same
as on the Cole car, Fig. 73C
66. Determining Firing Order of Eight-cylinder Engine. — If it be-
comes necessary to determine the firing order of an eight-cylinder engine,
it can be easily done by assuming that the cylinders are numbered as in-
dicated in Fig. 73D. The firing order for the right block is determined
by cranking the engine so that cylinder No. 1 is on compression. By
further cranking it can be determined whether cylinder No. 2 or cylinder
No. 3 is next on compression. If No. 1 is followed by No. 2, the firing
order for the block will be 1, 2, 4, 3; if No. 1 is followed by No. 3, the order
will be 1, 3, 4, 2. The firing order of the engine can then be determined
by starting with right cylinder No. 1, following this with the left cylinder
No. 1, and then by ft2, L2, ft4, L4, ft3, L3, if the firing order of the block
is 1, 2, 4, 3. If the firing order of the block is 1, 3, 4, 2, then the order
for the engine will be ftl, LI, ft3, L3, ft4, L4, ft2, L2.
67. Packard Twelve-cylinder Engine. — The twelve-cylinder engine
used on the Packard car is shown in Figs. 74 and 75. The twelve cylinders
are cast in two blocks of six each, arranged in a V with an included angle
of 60°. The left block of cylinders is set ahead of the right one by 1J£ in.
in order to permit the lower end of the connecting rods of opposing cylin-
ders to be placed side by side on the same crank pin. This arrangement
permits the use of a single camshaft with a separate cam for each valve,
making 24 cams on the camshaft. A silent chain drives the camshaft
which is placed directly above the crankshaft. The cylinders are 3-in.
bore by 5-in. stroke with L-head valve arrangement. The exhaust mani-
folds from the two blocks are joined near the rear of the engine, and the
exhaust gases are led to the muffler placed along the left side of the
frame. The crankshaft is' of the conventional six-cylinder type with
three main bearings. The engine is built into a single unit with the clutch
and transmission.
68. National Twelve-cylinder Engine. — On the National twelve-cyl-
inder engine, Fig. 76, the valves are placed on the outside of the V instead
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AUTOMOBILE POWER PLANTS
61
Fia. 74. — Packard twelve-cylinder engine.
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Flo. 75. — Packard twelve-cylinder engine in car.
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62
THE GASOLINE AUTOMOBILE
of on the inside. The cylinders are set exactly opposite, forked connect-
ing rod ends permitting both rods to bear on the one crank pin. The
cylinder heads are made removable, permitting easy access to the cylinder
and valves. A separate camshaft is provided for each cylinder block
with a separate cam for each valve. The intake manifolds are sur-
rounded by the hot water connection at the top of the cylinders. The
intake passages leading to the valves are cast integral with the cylinders.
Each set of cylinders has its own exhaust manifold pipe and muffler.
Fio. 76. — Details of construction on National twelve-cylinder engine.
The crankshaft is of the conventional six-cylinder type with three main
bearings. The cylinders are 2%-in. bore by 4%-in. stroke with a total
piston displacement of 370 cu. in. The horse power according to the
S.A.E. formula is 39.7 but on dynamometer test 77 horse power have
been delivered.
69. Pathfinder Twelve-cylinder Engine. — The Pathfinder twelve-cyl-
inder engine, Fig. 77, has its cylinders cast in blocks of three instead of
six as is customary. The head for each side of the engine is cast in one
piece with the intake manifold and water outlet integral for each set of
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AUTOMOBILE POWER PLANTS
63
six cylinders. The right set of cylinders is placed 1 J£ in. ahead of the
left on account of the connecting rods. The valves are placed in the
head and are operated through rocker arms at the top of the motor head.
One camshaft placed above the crankshaft serves all of the 24 valves.
The motor is built as a unit with the clutch and transmission and has
three point suspension.
Fiq. 77. — Twelve-cylinder engine in Pathfinder.
60. Firing Order of Twelve-cylinder Engines. — The several methods
of numbering the cylinders on a twelve-cylinder engine are shown in
Fig. 78. The firing order in each block is similar to that in a six-cylinder
engine and is usually 1, 5, 3, 6, 2, 4 or 1, 4, 2, 6, 3, 5 with the cylinders
numbered as iu Fig. 78-4, the impulses alternating from one side to
another.
On the Packard engine, numbered as in Fig. 78-4, the firing order is
1R, 6L, 4i2, 3L, 2R, 5L, QR, LL, 3#, 4L, 5#, 2L, corresponding to a firing
order for each block of 1, 4, 2, 6, 3, 5. On the Pathfinder, numbered as
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64
THE GASOLINE AUTOMOBILE
in Fig. 78C, the firing order is 1/J, 1L, 4iJ, 4L, 2/2, 2L, 6/2, 6L, 3/2, 3L,
5/2, 5L. This is the same order as is used on the Packard.
With cylinders numbered as in Fig. 785, the order of firing for the
National twelve is 1, 12, 9, 4-, 5, 8, 11, 2, 3, 10, 7, 6. This corresponds
to an order of 1, 5, 3, 6, 2, 4, for each block numbered as in Fig. 78 A.'
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Fiq. 78. — Numbering of cylinders on twelve-cylinder engines.
A power impulse comes every 60° or % revolution of the crankshaft.
Two and sometimes three power impulses are effective on the crankshaft
at the same time, thus insuring a steady flow of power from the engine.
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CHAPTER IV
FUELS AND CARBURETTING SYSTEMS
One of the most important operations in a gas engine is that of get-
ting an explosive charge inside of the engine cylinders at the proper
time. This explosive mixture is formed by the thorough mixing of air
and a gas formed by the evaporation of a volatile liquid fuel, usually
gasoline. The process of vaporizing the liquid fuel and mixing it with
the proper amount of air is called carburetion, and the device for doing
this is called a carburetor.
61. Hydrocarbon Oils. — Most of the liquid fuels are known as hydro-
carbon oils because they come from crude mineral oil containing as its
principal parts, hydrogen and carbon. Crude oil contains about 85 per
cent, carbon and 15 per cent, hydrogen by weight. One of the hydro-
carbon fuels, viz., alcohol, is not of mineral derivation, but is made by
the distillation of vegetable matter.
The crude oil or petroleum from which the hydrocarbon fuels are
made is found in natural deposits several hundred feet below the surface
of the earth. In some places it is necessary to pump the oil out, while
in others it is forced out by natural gas pressure. Most of the crude oils
found in the United States comes from Pennsylvania, Ohio, Illinois, Kan-
sas, Texas, Oklahoma, and California. These crude oils are of two gen-
eral types, that coming from Texas, Oklahoma, and California having
what is known as an asphalt base, and that from Pennsylvania and Ohio
having a paraffin base. Crude oil having an asphalt base is a heavy,
dark liquid, which, when distilled, leaves a black, tarry residue. Crude
oil having a paraffin base is much lighter in weight and color and, when
distilled, leaves a residue from which is made the white paraffin or wax
with which everyone is familiar. Gasoline made from crude oil with a
paraffin base was formerly supposed to be of a higher grade than that
from an asphalt base, but with the modern processes of refining, the gaso-
line from either kind of crude oil gives equally good results.
62. Refining of Petroleum. — The crude oil or petroleum is heated in
large retorts or stills, provided with accurate temperature recording
devices. A typical refining still is shown in Fig. 79. When the tempera-
ture in the still has reached about 100°F. vapor begins to rise from the
oil. This vapor is collected from the top of the still and condensed in
cooling coils, from which the liquid is collected in tanks. As the tem-
5 65
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66
THE GASOLINE AUTOMOBILE
perature in the still rises, the vapor becomes heavier and, when con-
densed, forms the heavier and less volatile liquids which are collected
Fig. 79. — Still for the refining of crude petroleum.
in other tanks as illustrated. The following table gives, approximately,
the products of this method of distillation:
Temperature in the retort
Kind of oil after condensing
the vapor
Percentage by weight
100°F. to 125°F.
125°F. to 350°F.
Over 360°F.
Gasoline distillate (Highly
volatile oils, as gasoline,
benzine, and naphtha)
Illuminating oil distillate
(Kerosene and light lubri-
cating oils)
Gas oil and lubricating dis-
tillate
(Heavy oils, paraffin wax,
and residue)
10 to 15 per cent.
65 to 75 per cent.
15 to 20 per cent.
It will be noticed that there is from three to five times as much kerosene
and light lubricating oils produced as there is gasoline. This part of the
refining process is called separation into groups because the more volatile
portions of the crude oil are separated from the less volatile portions.
The light or more volatile portions, like gasoline, vaporize very easily
but the less volatile and heavy portions are vaporized with difficulty.
As can be seen, these several portions are grouped according to beginning
and end boiling points. The groups from which gasoline is made are
the gasoline distillate and illuminating oil distillate.
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FUELS AND CARBURETTINO SYSTEMS
67
These two groups are then redistilled, as shown in Fig. 80. The
gasoline distillate or crude gasoline, after being treated in the agitator,
goes into a steam still where it is divided into the various grades of
gasoline having different boiling points and volatility.
63. Gasoline. — Gasoline, as used for automobiles, is a physical
mixture of hydrocarbon oils which can be vaporized to form an explosive
mixture. Gasoline is classified either as straight-run, cracked, or casing-
head, according to the method by which it is obtained. Straight-run
gasoline is the first product of distillation of the crude oil. It is distilled
between the boiling points of approximately 100°F. and 125°F. Casing-
head gasoline is made by compressing and liquefying certain gases coming
from oil wells. The liquid is then distilled under pressure giving very
light and volatile gasoline which is usually mixed or blended with that
of another quality for market purposes. The casing-head gasoline
Fio. 80. — Redistilling of crude gasoline into various grades.
is hardly ever used as it comes from the still because, on account of
its volatility, too much of it evaporates in handling. Cracked gasoline
is that made by breaking up or cracking the high boiling point prod-
ucts obtained by the first distillation of the crude oil. The cracking
is done by redistilling under heat and pressure. The Burton process
used by the Standard Oil Company and the Ritmann process are both
cracking processes. A large proportion of market gasoline consists of
mixtures or blends of the above qualities of gasoline. The blending
is done so as to insure vaporization in the carburetor. The blends are
usually about equal in fuel value and are usually heavier and less volatile
in summer than in winter.
Gasoline satisfactory for automobile use should be volatile enough
so that the engine can be easily started under ordinary conditions.
This means that if the gasoline is blended it should contain some low
boiling point product which will vaporize first for starting purposes.
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68 THE GASOLINE AUTOMOBILE
If the blend contains very heavy products with high boiling points, it
is possible that it may not even vaporize in the engine cylinder but
will be partially burned leaving an excessive carbon deposit. It is,
therefore, desirable to have the initial and end boiling points of the
gasoline or gasoline ' blend as low as possible. Less trouble is usually
found with straight-run gasoline than with the blended fuel, but in order
to conserve the straight-run, which is limited in quantity, it is usually
blended with low volatile gasoline.
64. Principles of Vaporization. — Before an explosive mixture can be
formed, the liquid fuel must first be atomized or vaporized and then
mixed with the proper amount of air to burn it. As we know, it requires
heat to change water into steam or vapor. If the water is out in the
open, it will evaporate rapidly, or boil if heated to a temperature of
212°F. Likewise, in order to change a liquid fuel into a gas or a vapor,
it is necessary that heat be added to it, but the temperature at which
this heat must be added is different for different fuels. For instance,
gasoline will evaporate under the usual atmospheric pressure and tem-
perature, and will, in some cases, evaporate at lower temperatures.
This can be tested by exposing a dish of gasoline to the air. In a short
time, the liquid will have evaporated. That heat has been absorbed
can be verified by feeling the dish before it is filled and again after
evaporation has been taking place. Consequently, we see that heat is
necessary before a liquid fuel can be vaporized.
Kerosene and alcohol, on the other hand, will not evaporate until
heat is added from an external source at a higher temperature, the
same as is done when steam is made from water. This explains the
difficulty of evaporating these fuels for use in a gas engine.
From the above considerations, some general principles of vaporiza-
tion cau be stated :
1. The heavier a liquid and the higher its boiling point, the harder
it will be to vaporize; for example, kerosene as compared with gasoline.
2. A liquid fuel will vaporize easier and faster under suction, or
reduction of pressure, than under pressure; for example, gasoline is more
difficult to vaporize at low than at high altitudes.
3. The closer the temperature of a liquid fuel is to its boiling point,
the easier and faster it will vaporize; for example, gasoline will vaporize
more readily in summer than in winter.
66. Testing Gasoline. — Gasoline is usually spoken of as high or
low test. By reference to the principles of vaporization, we see that
the heavier a liquid, the more difficult it is to evaporate. This prin-
ciple explains the basis of the Baume test. A hydrometer such as shown
in Fig. 81 is graduated in degrees, the numbers reading from the bottom
up. These degrees have nothing to do with the thermometer degrees,
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FUELS AND CARBURETTING SYSTEMS
69
but are named after Baumg, who originated the idea. When the hydrom-
eter is placed in a quantity of gasoline, it will sink to a depth corre-
sponding to the density of the liquid. It will sink deeper in a light
gasoline than in a heavy one. The deeper the hydrometer sinks, the
higher the scale reading will be. This scale, usually reading from 45°
to 95° Baum6, indicates in a very indirect way the ease and rapidity with
which the gasoline or fuel will evaporate. It is not a direct nor an
absolute test unless the exact nature and the boiling points of the gaso-
line are known. For most pur-
poses, it serves as a guide as to the
way the gasoline will act in service. '
The commercial gasoline of to-
day has a Baum6 test of from
56° to 65°, the high test being
in the neighborhood of 65° and
the low test in the neighborhood
of 66°. For summer use, the low
test or heavier gasoline can be
used because it will evaporate with
comparative ease at the usual
summer temperatures, but for
winter use the high test or light
gasoline is to be preferred because
it will evaporate more easily at the
low temperatures.
Occasionally, a low grade, im-
pure gasoline is sold which lacks
sufficient refinement and purifica-
tion, the sulphur and other impuri-
ties not having been eliminated.
The use of this may result in car-
bon deposits in the cylinders. A
gasoline that readily carbonizes
should be avoided and a higher
grade used. A simple test can be
made by burning some of the gasoline in a porcelain dish or crucible.
If the residue is slight, with practically no deposit on the bottom, the
gasoline is comparatively good. If the residue is of a heavy black
nature, the gasoline is of low quality and will not give satisfactory service.
The best tests for practical purposes can be determined from the
service of the car. With proper carburetor adjustments, the engine
should start easily, should give a maximum number of miles per gallon,
Fio
Kerosene Gasoline
81. — Baume hydrometer in kerosene
and gasoline.
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70 THE GASOLINE AUTOMOBILE
and should leave the cylinders comparatively free from carbon deposits.
No gasoline should be found in the lubricating oil of the crank case.
66. Kerosene and Alcohol. — Kerosene and alcohol are not used to
any great extent in automobiles on account of the fact that both are
extremely hard to vaporize. Several more or less successful devices have
been tried for using kerosene, but the varying speed&and loads of the
automobile engine make the problem of controlling the heat very difficult.
The price of gasoline and the prospects for a greater increase in the
supply make it unlikely that any great development in the use of kerosene
or alcohol will take place. Consequently, the discussion will deal only
with gasoline and its vaporization.
67. Heating Value of Fuels. — The heating value, or the amount of
heat energy contained in a liquid fuel, is given in British thermal units
per pound; a British thermal unit, or a B.t.u., being the quantity of heat
energy required to raise the temperature of 1 lb. of water 1° on the Fahren-
heit scale. The following table gives the heating values of the common
fuels:
Gasoline 18,000 to 19,500 B.t.u. per pound.
Kerosene about 20,000 B.t.u. per pound.
Alcohol (grain) about. . 10,000 B.t.u. per pound,
(wood) about. . 7,500 B.t.u. per pound.
Inasmuch as the heavier fuel contains more pounds per gallon, and as
gasoline and kerosene are sold by the gallon, a gallon of heavy or low
test gasoline or of kerosene contains slightly more energy than a gallon
of light, or high test gasoline.
68. Gasoline and Air Mixtures. — It is necessary when gasoline is
vaporized or atomized that the vapor be mixed with the proper amount of
air to form an explosive mixture. The air supplies the oxygen necessary
for combustion. If too little air is furnished, there will not be enough
oxygen to burn the carbon and hydrogen in the fuel, and the fuel will be
wasted as will be indicated by the black smoke coming from the exhaust.
If less than 7 parts by weight of air are furnished to 1 part by weight of
gasoline the mixture will not be combustible. If too much air is fur-
nished, the mixture will be weak in fuel, giving a very slow combustion.
This results in lost power. A weak mixture, or an excess of air, is indi-
cated by back-firing through the carburetor. The mixture becomes
non-combustible if more than 20 parts of air by weight are furnished to 1
part of gasoline by weight. On an average, a proportion of 15 parts of
air by weight to 1 part of gasoline by weight will give the best results.
The burning or exploding of a fuel charge of the proper proportions
gives out a blue color such as is found in the flame of a properly adjusted
gas stove. Too much air gives a white flame, and too much fuel gives a
reddish flame.
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FUELS AND CARBURETTING SYSTEMS
71
A definite mixture of gasoline vapor and air is necessary for the most
efficient operation of a gasoline engine. The function of the carburetor
is to take the gasoline, vaporize or atomize it, and furnish the proper
mixture of vapor and air to the cylinder under all conditions of tempera-
ture, speed, load, power, and varying atmosphere.
69. Principles of Carburetor Construction. — Most of the modern types
of carburetors are of the spray or nozzle type, in which a jet of atomized
gasoline is sprayed from a nozzle into a current of air to form an ex-
plosive mixture. Figure 82 illustrates a very elementary spray or
nozzle type carburetor. The gasoline supply tank is placed below the
carburetor and the gasoline is pumped up through the supply pipe to the
supply chamber C The overflow pipe maintains the level of the liquid
at a constant height. The standpipe or nozzle T is connected with the
from ptffTh
F/oat chamber
Butferffy
SthroHft
Ovir-fto
to tank
Fhaf
3%/ppfyX
A PiP*
Fig. 82. Fio. 83.
Figs. 82 and 83. — Elementary types of carburetors.
supply chamber C by means of the connection N, the flow being regulated
by the needle valve S. The gasoline level in the standpipe or nozzle T is
always just below the tip or end of the nozzle. The flange B is fastened
to the intake passage of the engine. With the intake valve open, the
suction of the piston causes a rapid flow of air through the air opening A
upward past the nozzle, drawing a spray of gasoline into the air. The
air and gasoline vapor form the explosive mixture for the engine cylinder.
The butterfly valve D in the air passage is for the purpose of in-
creasing the suction on the gasoline in the nozzle T when the engine
is being started and the suction is low. This valve should then be
completely or partially closed. When the engine is running, the valve
D should be wide open, in order to admit sufficient air to the cylinders.
This valve is sometimes called the choke valve.
The gasoline supply is regulated by adjusting the needle valve S.
This simple type of carburetor can be used only on constant speed
engines, the reason for which will be seen later.
Figure 83 shows another elementary type of carburetor which illus-
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72 THE GASOLINE AUTOMOBILE
trates the application of two modern ideas. In this carburetor, the gaso-
line supply is maintained at a constant level in the supply or float chamber
by means of a hollow metal float operating a ball valve. This arrange-
ment requires that the gasoline supply tank be placed above the carburetor
or that some other means be provided for supplying the gasoline to the
float chamber. It will also be noticed that the passage surrounding the
standpipe or spray nozzle is contracted, giving the inside surface a convex
shape. This is the application of the well-known Venturi tube principle.
By contracting the section near the opening of the nozzle the velocity
of the air and, consequently, the suction at that point are increased, thus
making it much easier for the gasoline to be taken up, and greatly facili-
tating the starting of an engine when the suction is low.
The gasoline needle valve is placed in the nozzle and the flow of gaso-
line is regulated from below. In many of the more modern carburetors
this needle valve is adjusted automatically, opening and closing accord-
ing to the demand. It is then called a metering pin.
70. Auxiliary Air Valves. — If the carburetor in Fig. 82, or the one in
Fig. 83, be put on a variable speed engine such as used on an automobile
and the adjustment made by regulating the needle valve so that the
mixture proportions of gasoline and air are correct at low speed, and
the engine should then be speeded up, black smoke would come from the
exhaust, indicating an excess of gasoline in the mixture. This would be
due to the fact that under the increased suction, due to the higher speeds
of the enginfe and piston, the air drawn in past the gasoline nozzle expands
and increases in volume and velocity faster than it increases in weight.
This means that at high engine speeds and under the consequent increased
suction, too much gasoline is supplied for the amount of air drawn in.
In order to keep the mixture of the proper proportions at all speeds of the
engine, it is necessary to have an auxiliary air entrance such as indicated
at X in Fig. 84 to admit an additional amount of air at the higher engine
speeds, or some other method of automatically regulating the proportion
of air and gasoline must be provided. This auxiliary air entrance is usu-
ally in the form of a mushroom valve controlled by a spring, the tension
on which can be changed to control its opening and closing. For low
speed adjustments the gasoline needle valve is used, and for high speed
adjustments the auxiliary air valve is used. That is, when the engine is
running at low speed, the air is taken in through the ordinary air opening
A shown below the valve in Fig. 84. The mixture is then proportioned
by regulating the gasoline needle valve NV. When the engine speeds up
and the suction is increased, the auxiliary air valve X in Fig. 84 comes
into action and by opening furnishes more air. If it is found that the
mixture at high speeds is too rich, that is, if there is too much fuel for the
air furnished, it indicates that the tension on the valve spring is too great,
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FUELS AND CARBURETTINO SYSTEMS
73
which prevents the valve from opening to admit sufficient air. By
reducing the tension, the valve opens wider, letting in sufficient air to
keep the mixture uniform. If the mixture is too weak at high speeds,
the spring tension is too weak, admitting an excess of air. The spring
should be tightened so as to permit less air to enter, and to increase the
suction on the gasoline.
It has been found that if the auxiliary air valve be provided with
a straight coil spring there will be considerable difficulty in keeping
the mixture of the proper proportions. The tendency is for too much
air to be supplied at high speed and open throttle. This objection has
been met by the use of a tapered coil spring such as S, in Fig. 84, instead
of a straight one. The tapered spring is better because it prevents the
air valve from opening too wide and furnishing too much air on open
throttle. In some cases, two coil springs are used on the auxiliary
Fig. 84. Fio. 85.
Figs. 84 and 85. — Typical variable speed carburetors
air valve. One of these regulates the air opening at medium speed and
the other comes into play at high speed to prevent the valve from opening
too wide.
Numerous other ways have been devised for supplying the auxiliary
air. A series of weighted balls, B, B, B} Fig. 85, rise and admit the
auxiliary air at various engine speeds. The weights of these balls have
been determined by experiment and no method of adjustment is provided.
The reed air .passage on the Tillotson carburetor, Fig. 104, and the
flat hinged valve on the Marvel, Fig. 93, illustrate other methods of auxil-
iary air supply.
In many of the modern carburetors a secondary gasoline jet or nozzle
furnishes a small amount of fuel to the auxiliary air, making it a very
lean mixture. This secondary jet may be either of the metering pin
type as on the Rayfield, Fig. 95, in which a certain opening of the air
valve automatically opens the metering nozzle, or, it may be of the
suction type, as on the Marvel, Fig. 93, in which a certain engine speed
produces sufficient suction to draw the gasoline out in a finely atomized
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74 THE GASOLINE AUTOMOBILE
condition. By thus supplying a small amount of fuel to the auxiliary air,
the tendency of the mixture to thin out at high speeds is avoided. The
high speed power demands may also be taken care of.
71. Air Valve Dashpots. — With the mushroom type air valve there is
occasionally considerable fluttering of the valve and also excessive noise
of the valve when it closes on its seat. This is overcome by providing
a dashpot, usually filled with gasoline, which prevents the excessive
fluttering and noise of the valve. The Stromberg carburetor, Fig. 112,
and the Ray field, Fig. 95, are provided with dashpots on the air valve.
72. Float Chambers and Floats. — Float chambers may be eccentric,
as in Fig. 83, in which case the chamber is placed at the side of the carbu-
retor, or concentric in which the chamber is built central with the carbu-
retor body as in Fig. 84 or 86. The floats which regulate the height of
fuel in the chamber may be either of hollow metal as in Fig. 83 or solid of
cork as in Figs. 84 and 85. The hollow metal float must be air-tight
in order to prevent it from filling with gasoline. The cork float is usually
coated with shellac to form a water-tight covering. This keeps the
float from becoming water-logged and, consequently, useless.
73. Metering Pins. — In some types of carburetors the opening of the
gasoline nozzle or jet is fixed and cannot be regulated. In other types,
the gasoline supply is regulated by a valve such as shown in Fig. 83
and also in Fig. 85. In some cases, arrangements are made for auto-
matically opening and closing this pin valve which is called the metering
pin. It may be operated by the throttle, as on the Schebler L, Fig. 89,
by the auxiliary air valve, or by an adjustment on the dash under the
control of the driver.
74. Operating Conditions of the Carburetor. — Formerly, when gaso-
line was of higher grade and the engines of lower speed, the problem of
carburetion was simple, but with the necessary use of lower grade fuel and
the higher speed and power of the engines, the problem of satisfactory
carburetion is a very important and difficult one. The higher grade
fuels would evaporate easily and there was little danger of the vapor
condensing after it left the carburetor. The adoption of lower grade
and blended fuels made it necessary to provide means for easily vaporiz-
ing or atomizing these and also to prevent condensation after leaving
the carburetor. The usual way of doing this is to furnish external heat
to the carburetor and intake manifolc^ leading to the cylinders and also
to heat the incoming air and the gasoline. Some decided improvements
in the design of the manifold have also helped in the prevention of
condensation.
Figures 92 and 94 illustrate typical methods of heating the air going
into the carburetor. The air is taken from a stove surrounding the
exhaust pipe and goes through a flexible connection to the carburetor.
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FUELS AND CARBURETTING SYSTEMS
75
A regulating valve placed near the carburetor can be adjusted when it is
necessary to regulate the temperature by taking air from the outside.
The carburetor body is sometimes jacketed, and, either part of
the exhaust gases as in the Marvel, Fig. 93, or part of the cooling water
from the engine, is used to heat the carburetor body. This method
heats the gasoline as well as the air. In other cases the entire intake
manifold is kept hot by passing the exhaust gases through a jacket sur-
rounding it. This prevents the usual condensation which tends to take
place. An electric heating unit, Figs. 86 and 87, has also been used in
the float chamber to keep the gasoline warm
•ui to insure complete vaporization.
* If the explosive mixture going into the
cylinder be heated too much, it is expanded
¥iq. 86. — Electrical heating
unit for carburetor bowl.
Fiq. 87. — Connections for electrical heater for
carburetor.
so that a full charge cannot get into the cylinder and, consequently,
the power of the engine is reduced. The fuel and the air should be
heated just enough to insure vaporization and to prevent condensation.
Beyond this there is no advantage in heating the fuel charge.
Various methods of providing efficient carburetion are employed in
the numerous types of modern carburetors. These methods of construc-
tion and operation are described and illustrated for the following typical
carburetors.
\ 76. Schebler Model L Carburetor. — The Model L carburetor, Figs.
88\nd 89, is of the lift-needle or metering pin type and is so designed
that the amount of fuel entering the motor is controlled by means of a
raised needle working automatically with the throttle. The flow of gaso-
line can be adjusted for closed, intermediate, or open throttle positions,
each adjustment being independent and not affecting either of the others.
This carburetor has an automatic air valve, shown at the left in Fig. 89.
At high speeds or heavy loads, the suction raises this valve and admits
an extra supply of air. The opening of the throttle for high speed or a
heavy pull raises the needle valve and increases the supply of gasoline
to correspond with the increased air supply.
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76
THE GASOLINE AUTOMOBILE
The Model L is furnished with a warm air connection from around
the exhaust manifold leading into the primary air opening at the base of
the carburetor, as shown in Fig. 92.
This carburetor, as illustrated in Fig. 89, is equipped with a dash-
control to the air valve spring, this being
adjusted by a lever which is controlled by
a handle on the dashboard or steering post
of the car. Three types of these air con-
trols are illustrated in Fig. 90.
The Schebler L is also built with a dash-
pot on the air valve to prevent the unsteady
action of the valve and give a smooth and
satisfactory operation of the engine.
Adjusting Schebler Model L Carburetor. —
The carburetor should be connected to ihe
intake manifold so that it is located below
the bottom of the gasoline tank a sufficient
distance to be filled by gravity flow under
all running conditions. Where pressure feed is used, it is unnecessary
to locate the carburetor below the gasoline tank; also, when pressure is
used, it is never advisable to carry over 2 lb.
Fio. 88. — Schebler Model L
carburetor.
Fio. 89. — Section of Schebler Model L carburetor.
Before adjusting the carburetor it is necessary that the ignition be
properly timed; that there is a good hot spark at each plug; that the
valves are properly timed and seated; and that all connections between
the intake valves and the carburetor are tight. The carburetor should
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FUELS AND CARBURETTING SYSTEMS
77
be adjusted to the engine under normal running temperature, and not to
a cold engine.
In setting the carburetor, the auxiliary air valve is first adjusted so
that it seats lightly but firmly. The handle on the dash control should
be set in the center of the dashboard adjuster, and with this setting of the
handle, the tension on the air valve should be light yet firm. The needle
valve should be closed by turning the adjustment screw to the right. It
is then turned to the left about four or five times and the carburetor
primed or flushed by pulling up the priming lever and holding it up for
about 5 seconds. The throttle is opened about one-third and the engine
started. After closing the throttle slightly, and retarding the spark, the
throttle lever screw and the needle valve adjusting screw are adjusted
so that the motor runs at the desired speed and hits on all cylinders.
This is the low speed adjustment.
After getting a good adjustment with the engine running, the needle
valve adjustment should not be changed again. The intermediate and
Fia. 90. — Dashboard and steering column controls for Schebler carburetor.
high speed adjustments are made on the dials. The pointer on the right
or intermediate dial should be set about halfway between figures 1 and 3.
The spark should be advanced and the throttle opened so that the roller
on the track running below the dials is in line with the first dial. If the
engine back-fires, with the throttle in this position and the spark ad-
vanced, the indicator or pointer should be turned a little more toward
figure 3; if the mixture is too rich, the indicator should be turned back,
or toward figure 1, until the engine is running properly with the throttle
in intermediate speed position. For high speed adjustment the throttle
is opened wide and the adjustment made for high speed on the second dial
in the same manner as the adjustment for intermediate speed on the first
dial.
76. Schebler Model R Carburetor.— The Schebler Model R carbu-
retor, Fig. 91, is of the single-jet raised-needle type, automatic in action.
The air valve controls the lift of the needle valve so as to proportion or
meter automatically the? amount of gasoline and air at all speeds.
The Model R carburetor is designed with separate adjustments for
both low and high speeds. As the speed of the motor increases, the air
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78
THE GASOLINE AUTOMOBILE
valve opens, raising the gasoline needle and thus automatically increasing
the amount of fuel. The low speed adjustment is made by turning the
air valve cap A, which, through a lever, regulates the height of the needle
valve E and, consequently, the flow of gasoline from the nozzle. The
screw F regulates the tension on the air valve spring and gives the ad-
justment for high speed.
The Model R carburetor is equipped with an eccentric near the top
of the metering pin. This eccentric is controlled by the outside crank
lever B which in turn is operated either from the steering column or from
the dash. The eccentric raises or lowers the needle valve according to
Fiq. 91. — Schebler Model R carburetor.
the position of B which is under the control of the driver. The needle
can be raised by adjusting the dash control and an extremely rich mix-
ture furnished for starting and for heating up the engine in cold weather.
A choke valve is placed in the air bend.
The Model R carburetor must be installed with either steering or
dash control, in order to insure proper performance under all weather
conditions. It is also absolutely necessary to apply heat at low engine
speeds to insure proper vaporization of the fuel. A hot air drum and
tubing running from the exhaust manifold to the carburetor are used as
illustrated in Fig. 92.
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FUELS AND CARBURETTING SYSTEMS
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Adjusting Schebler Model R Carburetor. — The crank lever B, Fig. 91,
should be attached to the steering column or dash control, so that when
boss D of lever B is against stop C, the handle on the steering column or
dash control will register lean or air. Fig. 90. This is the proper running
position for lever B.
To adjust the carburetor, turn the air valve cap A to the right until
it stops, then turn it to the left one complete turn. To start the engine,
open the throttle about one-eighth or one-quarter way. When the en-
gine is started, let it run till it is warmed, then turn the air valve cap A
to the left until the engine fires perfectly. Advance the spark three-
quarters of the way on the quadrant; then if the engine back-fires on
quick acceleration, turn the adjusting screw F up (which increases the
tension on the air valve spring) until acceleration is satisfactory. Turn-
ing the air valve cap A to the
right lifts the needle E out of
the nozzle and enriches the
mixture; turning it to the left
lowers the needle into the
nozzle and makes the mixture
lean.
When the engine is cold or
the car has been standing,
move the steering column, or
dash control lever, toward
gas or rich. This operates
the crank lever B and lifts the
needle E out of the gasoline
nozzle, giving a rich mixture
for starting. As the engine warms up, the control lever should gradu-
ally be moved back toward air or lean to obtain best running condi-
tions, until the engine has reached normal temperature. When this tem-
perature is reached, the control lever should be at air or lean. For best
economy, the slow speed adjustment should be made as lean as possible.
77. Marvel Carburetor. — The Marvel carburetor, shown in Fig. 93,
is of the double nozzle type, the high speed nozzle coming into action at
high engine speeds. At low speeds, all the air is drawn through the
Venturi tube, where it takes up gasoline from the primary nozzle. The
flow from the primary nozzle is controlled by the adjusting screw A.
At high speeds, after the air has passed the choke damper, it divides,
part of it going through the Venturi tube around the low speed spray
nozzle, and the remainder passing to one side and opening the auxiliary
air valve against the pressure of its spring. The auxiliary or high speed
spray nozzle is placed near the top of the auxiliary air valve.
Fig. 92. — Hot air connection for Schebler
carburetor.
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80
THE GASOLINE AUTOMOBILE
The rush of air through the Venturi tube picks up and atomizes the
gasoline from the low speed nozzle and carries it in suspension past the
throttle end to the cylinders. When the suction at the auxiliary air
valve has increased sufficiently to open this valve and create a high air
Hot air jacket
~Arr intake
■ Choke dofhper
Verituri tube
Weedk vohe
Fio. 93. — The Marvel Model E carburetor.
velocity at this point, gasoline is also picked up from the high speed
nozzle and carried to the cylinders.
The choke damper in the air inlet is used only for starting the motor,
by partially shutting off the air supply and forcing the engine to draw in
a rich mixture.
*^^B
Ms \
wiiM
I
■Hi
^^_. ^-^^—
Fia. 94. — Hot air and heating connections for Marvel carburetor.
• To the throttle is connected a hot air damper, which, when open,
allows the exhaust gas from the engine to flow through a cored passage
around the throttle, where it maintains the proper temperature for the
mixture of gasoline and air. As the throttle is opened, the hot air damper
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FUELS AND CARBURETTING SYSTEMS 81
is closed. A tube connects this cored passage with another which sur-
rounds the Venturi tube and spray nozzle. Figure 94 shows this hot air
tube which is screwed into the exhaust manifold. When the exhaust pipe
stove is used to heat the carburetor air, a shutter is used near the car-
buretor to regulat the temperature according to weather conditions.
This shutter is regulated by hand from the instrument board on the dash.
Adjusting Marvel Carburetor. — The needle valve A should be turned
to the right until it is completely closed, and the air adjustment B three
complete turns to the right. Then the needle valve A is opened one
complete turn to the left. The engine is started with the air regulator at
hot until the engine is warmed up. The spark lever should be fully re-
tarded after which the gasoline adjustment A should be turned to the
right (closed) until the engine runs smoothly.
After the motor has warmed up, turn the air valve adjusting screw
B to the left, a little, at a time, until the motor begins to slow down.
This indicates that the air valve spring *is too loose. Turn it back to
the right just enough to make the motor run well.
To test the adjustment; advance the spark and open the throttle
quickly. The motor should take hold instantly and speed up at once.
The best adjustment is obtained when the gasoline adjustment is tinned
as far as possible to the right and the air adjustment as far as possible to
• the left. With this setting the engine should idle smoothly and accel-
erate quickly.
78. Rayfield Model G Carburetor.— This carburetor illustrated in
Figs. 95 and 97 has two gasoline jets and three air entrances, two of
which are auxiliary air inlets into the mixing chamber. There are no
air valve adjustments, but two gasoline adjustments, a low speed adjust-
ment and a high speed adjustment, are provided.
At low speeds, air is drawn into the mixing chamber through the
constant air opening, Fig. 95. This air passes around the nozzle and picks
up the gasoline which leaves the spray nozzle in the form of a spray.
When the speed increases, the upper automatic air valve opens, admitting
more air. The movement of the air valve causes the metering pin to
open the metering pin nozzle* This furnishes additional fuel to the charge.
The lower air valve opens and closes with the main or upper automatic air
valve, giving a greater volume of air in proportion to the greater amount
of gasoline to be vaporized. At high engine speeds, or when the throttle
is fully opened, the engine requires more gas and, consequently, a greater
volume of air to vaporize the gasoline which comes through the spray
nozzles. At low engine speeds, less gas is required and, consequently,
less air is necessary to vaporize the gasoline.
The upper automatic air valve is controlled by the tension on the coil
spring. The bottom end of the valve stem carries a dashpot filled with
6
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82
THE GASOLINE AUTOMOBILE
gasoline. This dashpot prevents fluttering of the air valves and also
acts to force the gasoline out of both gasoline nozzles when the throttle
is suddenly opened and quick acceleration is desired.
Fia. 95. — Section of Rayfield Model G carburetor.
The method of applying heat to the Rayfield Model G is illustrated
in Fig. 96. The upper water connection on the carburetor is run to B
where the temperature of the engine cooling water is highest. The
Fig. 96. — Connections for supplying heat to Rayfield Model G carburetor.
bottom water connection is run from the carburetor to the suction side of
the water pump at A. These connections provide a constant circulation
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FUELS AND CARBURETTING SYSTEMS
83
of hot water through the jackets on the carburetor. The constant air
opening is connected by a flexible tubing to stove F which is placed around
the exhaust pipe at G. The dash control wire is connected through
bracket J to arm H , Fig. 97, the movement of which opens or closes the
primary gasoline jet. A priming wire is also run to G, the priming lever.
HIGH 5PEED
ADJUSTMENT
TURN TO RIGHT FOR.
MOR.t GAS
Fio. 97. — Rayfield Model G carburetor.
Adjusting Rayfield Model G Carburetor. — With the throttle closed and
the dash control down in run position, Fig. 98, close the nozzle needle by
turning the low speed adjustment, Fig. 97, to the left until U slightly leaves
contact with the regulating cam M and then turn to the right about three
complete turns. Open the throttle
not more than one-quarter. Prime
the carburetor by pulling steadily
a few seconds on the priming lever
G. Start the engine and allow it to
run until warmed up. Then with
retarded spark close the throttle
until the motor runs slowly with-
out stopping. Now, with the
motor thoroughly warm, make the
final low speed adjustment ty turning the low speed screw to the left
until the engine slows down. Then turn it to the right a notch at a
time until the engine idles smoothly.
To make the high speed adjustment, advance the spark one-quarter.
Open the throttle rather quickly. Should the motor back-fire it indicates
a lean mixture. Correct this by turning the high speed adjusting screw to
Fiq. 98. — Dash control handle for Rayfield
carburetor.
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84
THE GASOLINE AUTOMOBILE
the right about one notch at a time, until the throttle can be opened
quickly without back-firing. If loading (choking) is experienced when
running under heavy load with the throttle wide open, it indicates too rich
a mixture. This can be overcome by turning the high speed adjustment
to the left.
V 79. Holley Model H Carburetor. — Before the gasoline enters the
float chamber of this carburetor, Fig. 99, it passes a strainer disc A which
removes all foreign matter that might interfere with the seating of the
float valve B under the action of the cork float C. The gasoline passes
from the float chamber D
into the nozzle well E through
a passage F drilled through
the wall separating D and E.
From the nozzle Well, the fuel
enters the cup G through the
opening H, and rises past the
needle valve I to a level
which partially submerges the
lower end of the small tube J
which has its outlet K at the
edge of the throttle disc.
Cranking the engine, with
the throttle kept nearly closed,
causes a very rapid flow of air
through the tube J and its
calibrated throttling plug K.
With the engine at rest the
lower end of this tube is
partially submerged in fuel.
Therefore, the act of cranking
automatically primes the
engine. With the engine
turning over under its own
power, the flow through the tube J takes place at very high velocity,
causing the fuel, entering the tube with the air, to be thoroughly
atomized upon its exit from the small opening at the throttle edge.
This tube is called the low speed tube, because for starting and idle
running, all of the fuel and most of the air in the working mixture are
taken through it.
As the throttle opening is increased beyond that needed for idling of
the motor, a considerable volume of air is drawn down around the outside
of the strangling tube L and then upward through this tube. In its
passage into the strangling tube, the air is made to assume an annular,
Fiq. 99. — Holley Model H carburetor.
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FUELS AND CARBURETTING SYSTEMS
85
converging stream form so that the point in its flow at which it attains
its highest velocity is in the immediate neighborhood of the upper end of
the standpipe M . The velocity of air flow being highest at the upper or
outlet end of the standpipe, the pressure in the air stream is lowest at the
same point. For this reason, there is a pressure difference between the
top and bottom openings of the pipe M , thus causing air to flow through
it from bottom to top, the air passing downward through the openings N
in the bridge supporting the standpipe and then up through the standpipe.
100. — Temperature regulator used with Holley carburetor.
With a very small throttle opening, the action through the standpipe
keeps the nozzle cup thoroughly cleaned out, the fuel being carried directly
from the needle opening into the entrance of the standpipe. To secure
the best vaporization of the fuel, the passage through the standpipe is
given an aspirator form, which further increases the velocity of flow
through it and insures the best possible mixing of the fuel with the air.
A further point is that the vaporized discharge from the standpipe enters
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86
THE GASOLINE AUTOMOBILE
the main air stream at the point at which the latter attains its highest
velocity and lowest pressure.
The Holley temperature regulator is shown in Fig. 100. Hot air is
taken from around the exhaust manifold to the carburetor through a
flexible coupling. The regulator is under the control of the dash adjust-
ment which can be made according to conditions.
There is but one adjustment, that of the needle valve J. The effect
of a change in its setting is manifest over the whole range of the engine.
80. Holley Model G Carburetor. — This carburetor, Fig. 101, is a
special design for Ford cars. The operation is the same as the regular
Model H already illustrated and described. The chief differences are
Fig. 101. — Holley Model G carburetor.
structural ones providing a horizontal instead of a vertical outlet, a
needle valve controlled from above instead of from below, and a simpli-
fication of design to secure compactness.
The gasoline from the float chamber passes through the ports E to
the nozzle orifice, in which is located the pointed end of the needle F.
The ports E are well above the bottom of the float chamber, so that, even
should water or other foreign matter enter the float chamber, it would
have to be present in very considerable quantity before it could inter-
fere with the operation of the carburetor. A drain valve D is provided
for the purpose of drawing off whatever sediment or water may accumu-
late in the float chamber.
The float level is set so that the gasoline rises past the needle valve
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FUELS AND CARBURETTING SYSTEMS 87
F and fills the cup G sufficiently to submerge the lower end of the small
tube H . Drilled passages in the casting communicate the upper end of
this tube with an outlet at the edge of the throttle disc. The tube and
passage give the starting and idling actions, ad described in connection
with the Holley Model H. The lever L operates the throttle in the mix-
ture outlet. A larger disc with its lever S forms a spring-returned choke
valve in the air intake for starting in extremely cold weather.
The dash adjustment consists of a handle or small thumb wheel
attached to a rod by which the needle valve F may be opened or closed.
The Holley temperature regulator may also be used with this carburetor.
81. Kingston Model L Carburetor. — Figure 102 show the construc-
tion of this carburetor which has been designed especially for Ford cars.
Gasoline enters the carburetor from the tank at the connection A and
is maintaiaed at a constant level, by
means of the float. A pool of gasoline
forms in the base of the U-shaped mixing
chamber and is always present when the
engine is not running. This aids in
positive starting. When the engine
starts, this pool is quickly lowered to
the point of adjustment of the needle
valve and continues to feed from this
point till the motor is stopped.
When the motor is running slowly,
the weighted ball air valve B rests
,. i Al .. x ii • -a Fig. 102.— Kingston Model L
lightly on its seat, allowing no air to carburetor.
pass through; consequently, all the air
must pass through the low speed mixing tube C. Due to the lower end
of this tube being close to the spray nozzle and all the low speed air
having to pass this point, the atomized gasoline drawn from nozzle D
becomes thoroughly mixed with air in its upward course and is carried in
this state to the engine.
When the throttle is opened slowly, the air valve B gradually leaves
its seat, permitting an extra air supply to enter and compensate for the
increased flow of gasoline produced by the greater suction of the
motor. In this carburetor the extra amount of gasoline for the start-
ing and warming up period can be obtained by opening the needle valve
from the dash or by the use of the choke throttle E placed in the air
passage.
When starting with a cold motor, this choke throttle should be closed.
This cuts off nearly all the air supply and produces a very strong suction
at the spray nozzle, which causes the gasoline to fill the jet and be carried
with the incoming air to the cylinders.
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88 THE GASOLINE AUTOMOBILE '
A drain cock G is placed at the lowest point in the bowl and should be
opened from time to time to discharge all water and foreign matter.
Adjusting Kingston Model L Carburetor. — The throttle should be
opened about five or six notches of the quadrant on the steering post and
the Spark fully retarded. The needle valve binder nut on the carburetor
should be loosened until the needle valve turns easily. The needle valve
is then turned (with dash adjustment) until it seats lightly. It should
be opened one complete turn. This will be slightly more than necessary
but will assist in easy starting.
The engine is started and the throttle opened or closed until the
engine runs at fair speed. It should be run long enough to warm up to
service conditions. Then, for purposes of adjustment, the throttle must
be closed until the engine runs at the desired idling speed. This can be
controlled by adjusting the stop screw in the throttle lever.
The lieedle valve should then be closed until the motor begins to lose
speed, thus indicating a weak or lean mixture. The valve should now be
opened very slowly until the motor attains its best and most positive
speed. This completes the adjustment. The throttle should be closed
until the engine rims slowly, and then opened quickly. The engine should
respond strongly and quickly. If the acceleration is slightly weak or
sluggish, a slight adjustment of the needle valve may be advisable to
correct this condition. With the adjustments completed, the binder
nut should be tightened until the needle valve turns hard.
82. Tillotson Carburetor. — This carburetor, Fig. 103, embodies a
unique method of regulating the air supply. This regulation, being
entirely automatic, the only other adjustment is the gasoline needle
valve. The air supply comes through the air opening at the top and is
drawn through the V shaped passage formed by the steel reeds, the exact
construction of which may be clearly understood from Figs. 104 and 105.
The two steel reeds form an air passage which is really an automatic
adjustable Venturi tube. When the engine is still or running slowly, the
reeds bear against the side of the primary gasoline nozzle. As the engine
speeds up and the suction increases, the mouth of the V opens, giving a
greater air passage and at the same time producing the maximum air
velocity past the gasoline nozzle. Figure 104 represents the various
positions of the two reeds as the mouth of the V opens.
Provision is also made for a small jet of air to pass up through the
primary nozzle from the bottom. This air atomizes the charge of
gasoline thoroughly and sprays it into the main charge of air coming
through the reed opening.
The secondary gasoline jet coming up from the float chamber between
the reeds also supplies gasoline to the incoming air when the engine
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FUELS AND CARBURETTING SYSTEMS
89
speed is high, and the suction at the large part of the Venturi is sufficient
to draw the gasoline out of the secondary jet.
Fig. 103.— Tillotson Model B carburetor.
Fig. 104. — Steel reed air valve on Tillotson carburetor.
Adjusting Tillotson Carburetor. — There is only one adjustment to
make, that of the gasoline supply for the primary nozzle. The engine
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THE GASOLINE AUTOMOBILE
should be thoroughly wanned up and the spark control lever retarded to a
position approximately one-third of the way upon the quadrant. The
throttle is then adjusted ntil the engine is turning at a speed equivalent
to approximately 15 miles per hour on the road. Then the gasoline needle
valve is turned to the right until the engine starts to misfire. The valve
should be opened slightly until the motor is firing regularly. Then the
engine should be suddenly accelerated by opening the throttle to the
extent of its travel. If there is any back-
fire, or spitting back, through the car-
buretor, the adjusting valve must be
opened still farther, until when suddenly
accelerated the engine picks up and fires
with regularity.
This is, theoretically, the proper car-
buretor adjustment. It is not the most
economical adjustment. Under certain
conditions of travel it will be found that
the motor will fire regularly and develop
maximum power with the carburetor ad-
justed to a point at which this back-firing
will occur when the motor is suddenly
accelerated. If constant high speed of the
motor is to be maintained, the latter ad-
justment will be entirely satisfactory.
83, Zenith Model L Carburetor.— This
carburetor, shown in Fig. 106, differs from
most conventional types in the absence of
auxiliary air valves. It is a fixed adjust-
ment carburetor, and has as its particular
feature the compound nozzle, invented by
Baverly. The compound nozzle has an
inner nozzle, the gasoline for which is
furnished direct from the float chamber.
The amount of gasoline leaving this
nozzle would make the mixture too rich
at high speeds. To compensate for this rich mixture, the compensat-
ing nozzle surrounding the main or inner nozzle furnishes a mixture
too weak at high speeds. This is because the gasoline feed to this jet
is constructed so as to be constant at all speeds. When the engine
speeds up, the amount of air increases and the compensating mixture
is a weak one. This answers the purpose of the auxiliary air valve on
other types of carburetors and' keeps the mixture of constant proper-
ly
Fio. 105. — Primary fuel nozzle
and air valve on Tillotoon carbu-
retor.
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FUELS AND CARBURETTING SYSTEMS
91
tions. By a proper selection of the two nozzles a well balanced mixture
can be secured through the entire range.
In addition to the compound nozzle, the Zenith is equipped with a
starting and idling well. This well terminates in a priming hole at the
edge of the butterfly valve, where the suction is greatest when the valve
is slightly open. The gasoline is drawn up by the suction at the priming
hole and, being mixed with the air rushing by the butterfly, gives a rich
slow speed mixture. This slow speed mixture is regulated by the regu-
lating screw, which admits air to
the priming well. At higher
speeds, with the butterfly valve
opened, the priming well ceases to
operate and the compound nozzle
drains the well and compensates
for any engine speed.
84. Stewart Model 25 Carbu-
retor.— This carburetor, which is
manufactured by the Detroit
Lubricator Company, involves an'i
interesting principle of operation.
Figure 107 is a sectioned view of
this carburetor and shows the posi-
tion of the air valve with the
engine running and air and gaso-
line being admitted.
With the engine at rest and no
air passing through the carburetor,
the air valve A rests on the seat
B, closing the main air passage.
The gasoline rises to a height of about 1% in. below the top of the cen-
tral aspirating tube L. As soon as the engine starts, a partial vacuum
is formed above the air valve, causing it to lift from its seat and admit
air, at the same time gasoline is being drawn up through the aspirating
tube L. The lower end of the air valve extends down into the gasoline
and around the metering pin P. Due to the decreasing diameter of
this pin, the higher the air valve is lifted the larger the opening into the
tube L will be, and the more gasoline there will be drawn up. The
upper end of the air valve measures the air; the lower end measures the
gasoline; therefore, as the suction varies, the air valve moves up or
down and the volume of air and the amount of gasoline admitted to the
Trirring chamber increase or decrease in the same ratio. Most of the
air passing through the carburetor goes through the air passages, as
indicated by the black arrows. A small amount is drawn through the
Fig. 106. — Zenith Model L carburetor.
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92
THE GASOLINE AUTOMOBILE
drilled holes HH and past the end of the tube L. The flared end of
this tube deflects the air through a small annulus, thereby increasing
the velocity of air at this point so as to aid in atomizing the fuel.
The air valve is restrained from any tendency to flutter, caused
by the intermittent suction of the cylinders, by the dashpot D. Due
to the greater inertia of the gasoline and because it flows comparatively
slowly through the small opening and into the dashpot, the air valve can
rise or fall only as liquid is expelled or admitted. Thus the air valve is
held steady. The Stewart carburetors have but one adjustment, which
raises or lowers the metering pin, thereby decreasing or increasing the
Fig. 107. — Stewart Model 25 carburetor.
amount of gasoline admitted to the mixing chamber. The correct
position of the metering pin is determined with the motor running at
idling speed. This adjustment may be manipulated at the dash to
compensate for extreme changes in atmospheric temperatures and for
use in starting in cold weather.
85. Stromberg Plain Tube Carburetor. — In the Stromberg plain tube
carburetor, Figs. 108 and 109, both the gasoline and the air openings are
fixed in size. The gasoline is metered automatically by the suction of the
air past the gasoline jets. The flow of gasoline from the float chamber
is regulated by the high speed adjustment needle A} Fig. 109, the gasoline
flowing past the high speed needle seat through the opening F either to the
accelerating well or to the idling tube, through the opening at J. With
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FUELS AND CARBURETTING SYSTEMS
93
the engine not running, the gasoline rises in the accelerating well, idling
tube, and air bleeder to the same height as in the float chamber.
The air bleeder G, Figs. 109 and 110, is for the purpose of admitting
air through the openings D into the gasoline channel where it breaks up
the gasoline charge and carries it through a number of openings E into
the charge of air going through the small Venturi tube. By admitting
this small amount of air into the gasoline before it is sprayed into the air
current, it is possible to break down the surface tension of the liquid and
to break up the gasoline into a finely divided mist. This insures that the
fuel is completely atomized.
{CARBURETOR FLANGft
LARGE VENTURI
/THROTTLE VALVE
THROTTLE STEM
OR SHAFT
THE STROMBERC
PLAIN TUBE
CARBURETOR
With Motor it Ratf
IDLE DISCHARGE JET
IDLE ADJUSTMENT NEEDLE
HIGH SPEED ADJUSTMENT NEEDLE
FLOAT NEEDLE
STRAINER BODY'
GASOLINE'
CONNECTION
Fig. 108. — Strom berg plain tube carburetor.
Surrounding the main gasoline passage is the circular chamber M or
accelerating well. The purpose of this chamber is to furnish the extra
amount of gasoline needed when the throttle is suddenly opened and the
mixture must be somewhat richer. When the engine is running at slow
speed or slowing down, this accelerating well fills with gasoline. If the
throttle is suddenly opened and the engine speeds up, the gasoline from
this well flows through openings H, Fig. 109, to join the gasoline coming
from the float chamber. This doubles the normal rate of fuel supply.
The amount and rate of discharge from the well are determined by the
size and number of holes in the side of the well.
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94
THE GASOLINE AUTOMOBILE
In the center of the main gasoline passage is found the idling tube
through which the gasoline is furnished to the cylinder when the engine is
idling and the throttle is practically closed. Air is drawn into the idling
tube through the small opening under control of screw B and its needle
valve near the top of the large Venturi tube. This air being regulated
by B goes through the gasoline which it atomizes and sprays out into the
carburetor through K above the throttle valve. By means of B, the idle
adjustment needle, the amount of air is regulated and the idling mixture
is correctly proportioned.
Fig. 109. — Sectioned view Strom berg plain tube carburetor.
As the throttle is slightly opened from the idling position a suction
is created on the throat of the small Venturi tube as well as on the idling
jet. When idling, the suction is greater at the idling jet, and when the
throttle is open the suction is greater at the small Venturi tube. At
some intermediate position of the throttle there is a time when the action
at the idle jet is equal to that at the small Venturi, and at this particular
time gasoline will go both ways to the cylinders. This condition lasts
but a very short time because as the throttle is opened wider, the suction
at the small Venturi tube rapidly becomes greater than that at the idling
jet. The result is that the idling tube and idling jet are thrown entirely
out of action, the level of the gasoline in the idling tube dropping when
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FUELS AND CARBURETTING SYSTEMS 95
the throttle is open, in which case all of the gasoline enters the manifold
by way of the holes in the small Venturi tube.
Adjusting Stronzberg Plain Tube Carburetor. — The high and low speed
adjusting screws, A and J3, Fig. 109, should be completely turned down
so that the needle valves just touch their respective seats. The high
speed adjustment A should be unscrewed about 3 turns off the seat, and
the low speed adjusting screw B turned anti-clockwise about 1^ turns
off its seat. These settings are merely to be taken as a starting point,
because there is hardly any question but that the engine will start easily
with these settings, provided a spark is available and other things are in
proper condition.
To make the high speed adjustment, the spark is advanced to the
position for normal running and the gas lever on the steering wheel quad-
rant set to a position corresponding to an engine speed of approximately
750 r.p.m. The high speed screw A is gradu-
ally turned down (clockwise) notch by notch,
until a slowing down of the engine is ob-
served. The same screw should then be
turned up or opened (anti-clockwise) until
the engine runs at the highest rate of speed
for that particular setting of the throttle.
To make the idling adjustment on Bf re-
tard the spark fully and close the throttle as
far as possible without causing the motor tO Fig. HO.-— Air bleeder on
come to a stop. If upon idling, the motor ^rmberg plain tube "^
tends to load, it is an indication that the mix-
ture is too rich and, therefore, the low speed adjusting screw B should
be turned away from the seat (anti-clockwise), thereby permitting the
entrance of more air into the idling mixture. The low speed adjustment
is best made by carefully observing the smoothness with which the motor
revolves when idling, and can be properly obtained by turning the screw
B up or down, notch by notch, until the best idling prevails. It is safe
to say that the best idling results will exist when the screw B is not much
more or less than 1% turns off the seat.
After satisfactory adjustments have been made with the car station-
ary, it is advisable to take the car out on the road for further observation
and finer adjustment. If upon rather sudden opening of the throttle,
the motor back-fires, it is an indication that the high speed mixture is
too lean and in this case the adjusting screw A should be opened one notch
at a time until the tendency to back-fire ceases. On the other hand, if
when running along with open throttle the engine rolls or loads 7 it is an
indication that the mixture is too rich. This is overcome by turning the
high speed screw A down (clockwise) until this loading is eliminated.
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THE GASOLINE AUTOMOBILE
The Strorriberg Economizer. — It has been found that a richer mixture
is needed for power at wide open throttle than for ordinary pleasure car
driving at nearly closed throttle. With a carburetor giving a single mix-
ture proportion under all conditions, the best pulling power can be ob-
tained only with a considerable waste of fuel during ordinary closed
throttle driving. The operation of an engine at wide open throttle is
very much more sensitive to low temperatures than at closed throttle.
In addition, many drivers set the mixture unduly rich in the winter
months.
The Stromberg economizer, Fig. Ill, which graduates the gasoline
adjustment to best efficiency for each throttle position, has been devel-
oped for use on Stromberg carburetors. The high speed gasoline needle
A is held by the nut N which is supported on the lever arm M at closed
and open throttle. The proper needle adjustment for wide open throttle
Fig. 111. — Economizer on Stromberg carburetor.
is thus obtained with the nut N. But with the throttle in ordinary
driving positions, ranging from 15 to 40 miles per hour, the roller P drops
into the cam notch 0 which permits the lever arm to drop free, so that
the high speed nut is then supported upon the economizer nut R. This
lowers the high speed needle into its orifice, and partially cuts off the
gasoline for these speeds. The amount of drop can be regulated by the
pointer L which gives a special adjustment for the greatest possible
economy for these speeds. This does not interfere with the maximum
power adjustment.
86. Stromberg Model H Carburetor. — The Stromberg Model H car-
buretor, Fig. 112, is of the double-jet type with two adjustments, one
for high and one for low speed, both working on the gasoline supply.
The gasoline level in the glass float chamber is regulated by the hol-
low metal float. The fuel for low speed is furnished by the spray nozzle
in the Venturi tube, through which the low speed air passes. At high
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FUELS AND CARBURETTING SYSTEMS
97
speed, the auxiliary air comes through the auxiliary air valve, which in
turn automatically regulates the gasoline flow from the auxiliary gasoline
valve. This supplies the extra gasoline for high speed and heavy duty
service.
The dashpot with the piston riding in gasoline prevents all fluttering
of the air valve on its seat, when opening and closing.
-MOTUC SULUrMTVKMUVA*
AunuuK MaoLwricauMMUCMNtiisu
AUXILIARY CfcMLK NCDIX wuc CMC
Fiq. 112. — Stromberg Model H carburetor.
This type of carburetor is fitted with a strangling or choke valve in
the primary air inlet, for starting in cold weather. This assists in the
vaporization of the gasoline by increasing the suction on the liquid.
The spring tension on the air valve and auxiliary needle valve is con-
trolled either from the dash or from the steering post, depending upon
the style of control installed. This permits adjustment to be made
in order to compensate for varying conditions of weather, fuel, and
operation.
7
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98 THE OASOLINE AUTOMOBILE
87. Hudson Carburetor. — The Hudson carburetor. Fig. 113, is of the
metering pin type. The amount of gasoline furnished to the mixture
depends upon the height of the metering pin, which, as will be noticed,
has a tapering V groove. When the engine speeds up and the suction
is increased, the piston in the air chamber raises the pin, permitting a
greater amount of gasoline to be taken up by the incoming air. The
raising and lowering of the piston also increases or decreases the amount
of air going through the carburetor. In order to regulate the gasoline
supply from the steering wheel, a sliding sleeve on the bottom of the
metering pin can be raised or lowered by means of the feed regulator
lever, which is under control from the steering wheel or dash.
«-« i ;» M
ttCTIOKM VIEW
Fio. 113. — Hudson carburetor.
88. Cadillac Carburetor. — Several novel features are found on the
Cadillac carburetor, Fig. 114. The gasoline supply is through a nozzle
or standpipe placed at the throat of a Venturi tube. The primary air is
taken in through an opening on the side of the carburetor as indicated.
The auxiliary air valve consists of a hinged shutter controlled by a coil
spring.
The throttle pump shown is controlled by the movement of the
throttle valve.. Its purpose is to force gasoline through the spray nozzle
when the throttle is opened suddenly and the engine speeds up quickly.
When the throttle is opened slowly, the throttle pump has little or no
effect upon the gasoline in the nozzle.
89. Packard Carburetor. — This carburetor, Fig. 115, is of the con-
ventional auxiliary air valve type. The primary air supply at the left
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FUELS AND CARBURETTING SYSTEMS
99
of the carburetor furnishes the air at low speeds. This air current picks
up the gasoline from the standpipe. When the engine speed and the
suction are increased, the auxiliary air valve opens and supplies the addi-
*'THROTTLE
GASOLINE INLET
NEEDLE VALVE
AUJUUARrAlR
VALVE SPRING
Fia. 114. — Section of Cadillac carburetor.
tional air needed. The opening and closing of this valve is regulated by
the tension on its two springs. This tension is adjusted by two cams
underneath the springs. Connections to these cams are made on the con-
Fig. 115. — Packard carburetor.
trol board so that the adjustment can be made from the driver's seat.
This is the only adjustment to be made.
90. General Suggestions on Carburetor Adjustment and Operation. —
It is obviously impossible to give detailed instructions which will answer
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100 THE GASOLINE AUTOMOBILE
for all types of carburetors, but there are certain fundamental principles
which apply to the adjustment of all types.
There are numerous troubles coining from an engine 01 its auxiliaries
which apparently indicate the carburetor is at fault. These troubles
must be remedied before any adjustment on the carburetor can be satis-
factorily made. It must be ascertained if a good spark occurs in the
cylinder at the proper time; if each cylinder has the proper compression;
if the intake manifold or connections are free from air leaks; and if gaso-
line is being furnished to the carburetor.
The engine must be warmed to normal running conditions before any
adjustments are attempted. The engine should be run idle with the
spark retarded and the throttle open so that the speed of the car will be
around 15 miles per hour. The low speed adjustment, usually on the
gasoline, is made so that the engine hits smoothly and regularly after
which the spark is advanced and the engine speeded up. The high speed
adjustment, usually on the auxiliary air, is then made. With the engine
running slowly the throttle should be opened quickly to give the engine
a rapid acceleration. The engine should pick up quickly and fire uni-
formly. If upon opening the throttle the engine back-fires or spits back,
the mixture is weak and the gasoline adjustment should be made to pro-
vide more fuel. If the engine is to be run at practically constant speed
and there is little need of quick acceleration, the most economical adjust-
ment will be one which back-fires occasionally on rapid acceleration. A
loading upon accelerating indicates too rich a mixture.
A rich mixture is indicated by the overheating of the cylinders, waste
of fuel, choking of the engine, misfiring at low speeds, and by a heavy
black exhaust smoke with a very disagreeable odor. A weak mixture
manifests itself by back-firing through the carburetor and by loss of
power. A back-fire is caused by the fresh charge of mixture entering the
cylinder and coming in contact with the slow burning charge in the cyl-
inder. With the intake valve open, the force of the explosion comes
back through the carburetor. A proper mixture will give little or no
smoke at the exhaust. Blue smoke is caused by the burning of excess
lubricating oil and has no relation to the quality of the mixture.
The common carburetor troubles and remedies will be taken up fully
in Chapter XV.
91. Intake Manifolds. — The tendency in present engine design is to
make the intake manifold of such shape and proportions that the path
from the carburetor to the engine cylinders will be as short and as smooth
as possible. Being close to the cylinders, the manifold as well as the
carburetor is heated, and this greatly aids the vaporization of the gaso-
line. A short straight manifold gives the gas very little chance to con-
dense between the carburetor and the cylinders. It is also desirable to
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FUELS AND CARBURETTING SYSTEMS 101
have the distance from the carburetor to each of the different cylinders
the same. This insures the same amount of mixture to each cylinder.
On some engines, where the cylinders are cast en bloc, the manifold is
cored out in the casting, giving a short, smooth passage for the fuel charge.
It is necessary then merely to attach the carburetor to the cylinder
casting.
Several methods of casting the intake manifold to insure vaporization
of the fuel have been used. The exhaust and intake manifolds have been
combined so that the heat from the exhaust can assist in the vaporization
of the fuel in the intake manifold. The Wilmo manifold, Fig. 116, is
such a combination, in which the exhaust and intake manifolds are
divided by a thin wall. The high temperature of the exhaust increases
the temperature of the intake manifold and insures vaporization of the
fuel. Other methods such as casting the exhaust manifold around the
intake manifold, and also of providing hot spots in the intake manifold,
Fig. 116. — Wilmo manifold.
have been designed to insure vaporization and prevent condensation of
the fuel.
92. Carburetor Control Methods. — The carburetor is controlled from
the driver's seat. The hand throttle on the steering post regulates the
amount of mixture to the cylinders, thereby regulating the engine and
car speed. In conjunction with the throttle connection is the accelerator
on the toe-board. This permits the throttle to be opened by the foot,
independently of the hand lever. The accelerator must be held open by
the pressure of the foot. As soon as the pressure is removed from it, the
throttle closes to the point set by the hand lever. The air and gasoline
adjustment can usually be made from the dash of the car.
93. The Gasoline Feed System. — There are numerous systems for
feeding the gasoline to the carburetor from the gasoline tank, which
may be placed at the rear of the frame, in the cowl, or under the seat.
These feed systems are classified as gravity, pressure, and vacuum
systems.
The Gravity Feed System. — In the gravity system of gasoline feed, the
fuel flows to the carburetor by gravity alone. The tank may be placed
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102
THE GASOLINE AUTOMOBILE
either under the seat or in the cowl. If under the seat, there is the dis-
advantage of having to remove the cushions before being able to fill the
tank. There is also the possibility in some cases that the tank will
Fig. 117.— Typical gravity feed system with supply tank in cowl.
become lower than the carburetor, when going up hill, and, consequently
the gasoline will not flow to the carburetor. Both of these disadvantages
are done away with by placing the tank in the cowl. In either case,
iupply tank under front seat.
Fio. 118. — Gasoline supply system on Ford
however, the pressure on the carburetor float valve varies as the level in
the tank varies. When filling the tank, any gasoline which spills or
leaks, either falls around the seat, in the car, or on the engine. The
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FUELS AND CARBURETTING SYSTEMS
103
advantage of the gravity system is that it is simple and always ready.
Figure 117 shows a typical gravity system with the tank in the cowl.
The float operates the gasoline indicator, which is placed on the
dash. Figure 118 shows the gravity tank placed under the seat of the
Ford car.
The Pressure Feed System. — When the gasoline tank is placed at the
rear of the frame, it is obviously impossible to use the gravity system.
The gasoline may be forced to the carburetor by putting a pressure in
the gasoline tank. This pressure is maintained by a small air pump
operated by the engine, or by a hand pump, or both. After filling the
tank, a hand pump is used to get up pressure until the engine has been
Fig 119. — Pressure system of gasoline feed as used on Packard car.
started. A safety valve in the pressure system keeps the pressure from
getting too high. The particular advantage of this type of feed system
is that gasoline feeds to the carburetor regardless of the position of the
car. As in the gravity system, the pressure on the float valve is liable
to vary. The filler cap is placed away from the engine and passengers,
and gasoline may be put in without disturbance. A typical pressure
feed system is illustrated in Fig. 119.
The Vacuum Feed System. — Several systems have been developed in
which the gasoline is transferred from the main tank at the rear of the
car by a vacuum or suction to a small auxiliary tank near the engine.
From this small tank the gasoline flows by gravity to the carburetor.
Figures 120 and 121 show the installation of the Stewart vacuum system
in a car, and Fig. 122 indicates the construction of the auxiliary vacuum
tank.
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THE GASOLINE AUTOMOBILE
This system comprises a small round tank, mounted on the engine
side of the dash. This tank is divided into two chambers, upper and
lower. The upper chamber is connected by a pipe to the intake manifold,
while another pipe connects it with the main gasoline tank. The lower
chamber is connected with the carburetor.
Fig. 120. — The Stewart vacuum feed system.
The intake strokes of the motor create a vacuum in the upper chamber
of the tank, and this vacuum draws gasoline from the supply tank. As
the gasoline flows into this upper chamber, it raises a float valve. When
this float valve reaches a certain height, it automatically shuts off the
vacuum valve and opens an atmospheric valve, which lets the gasoline
Fig. 121. — Under the hood. — The Stewart vacuum feed system.
flow down into the lower chamber. The float in the upper chamber
drops as the gasoline flows out, and when it reaches a certain point, it in
turn reopens the vacuum valve, and the process of refilling the upper
chamber begins again. The same processes are repeated continuously
and automatically. The lower chamber is always open to the atmosphere
so that the gasoline always flows to the carburetor as required and with an
even pressure.
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FUELS AND CARBURETTING SYSTEMS
105
The gasoline always remaining in the tank gets some heat from the
engine and thereby aids carburetion; it also makes starting easier, by
reason of supplying warm gasoline to the
carburetor. The lower chamber of the tank
is constructed as a filter and prevents any
water or sediment, that may be in the gaso-
line, from passing into the carburetor. A
petcock, in the bottom of the tank, permits
drawing this sediment off and also allows the
drawing of gasoline, if required for priming
or cleaning purposes.
94. Care of Gasoline. — Gasoline, being a
volatile liquid, is very dangerous if not prop-
erly handled, but if proper care and attention
are given to it there should be no danger
whatever. It should never be exposed in a
closed room as it will evaporate, mix with
the air, and form a very explosive mixture.
Open lights should always be kept away
from gasoline. When it is necessary to
handle gasoline at night, it should be done
with an electric light. Do not under any con-
dition use an open light
In putting out a gasoline fire, water will
only spread the fire, as the gasoline, being
lighter than water, floats on it. The only
successful method of extinguishing a gasoline
fire is to smother it, either by sand, or a
blanket, or by the gases from a fire extin-
guisher.
The exhaust gases from a gasoline engine are very deadly. Do not
breathe them for any length of time. If it becomes necessary to run your
engine in a small garage with the doors closed, arrangement should be
made to pipe the exhaust to the outside air.
Fig. 122. — Stewart vacuum
tank.
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CHAPTER V
ENGINE LUBRICATION AND COOLING
95. Lubrication and Friction. — The purpose of lubrication is to reduce
the friction between moving surfaces. If parts rubbing on each other
are not separated by a film of lubricant, the surfaces will rub and rapidly
wear away. Friction is a force that tends to retard or to stop the motion
of one surface over another. The f rictional force depends on the nature
of the surface, and also on the kind of material. The rougher the surface
and the softer the material, the greater the friction; while the harder the
material and the smoother the surface, the less the friction. The more
friction there is, the greater the loss of power, as it requires power to over-
come friction. A great amount of friction is necessary in certain parts
of the car such as in the brakes, the clutch, and the outer surface of the
tires in order that they be efficient. On the other hand, it is essential
that all friction possible be eliminated from the bearings and pistons
in order to have as little of the engine power lost as possible. It is im-
possible to eliminate the friction entirely, but with the proper use of a
suitable lubricant, the loss due to friction can be reduced to a minimum.
The principal parts of the engine needing lubrication in order to prevent
friction are the main crankshaft bearings, connecting rod bearings, wrist pin
in the piston, camshaft bearings, half-time gears, pistons, and cylinder walls.
96. Lubricants and Lubrication. — Lubricants are used in the following
three forms: fluid oils, such as gas engine cylinder oil; semisolids, such
as soft grease; and solids, suchas graphite. These forms are used accord-
ing to the condition and nature of the surfaces to be lubricated, although
on automobile engines, lubricants in the fluid form are almost universally
used.
There are three general sources of lubricants: animal oils, such as
lard and fish oils; vegetable oils, such as olive, castor, and linseed oils; and
mineral oils which are secured from petroleum. The lubricants of mineral
derivation are generally used for gas engine lubrication because they
serve the purpose better, are more plentiful, and are cheaper.
A lubricant must be of such character and quality that it will not
break up or decompose at the temperature under which it will work. If
a lubricant for an engine cylinder decomposes at a temperature lower
than that in the cylinder, it will be useless for lubrication and the cylinder
walls will be cut. The lubricant must also have sufficient body to with-
stand the pressure subjected to it and should also be free from acids in
order to prevent the eating away and etching of the rubbing surfaces.
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THE GASOLINE AUTOMOBILE
97. Test of Lubricating Oils. — The following tests are made to deter-
mine the qualities of lubricating oils:
Viscosity. — Viscosity is the property of a liquid by which it has a
tendency to resist flowing. A liquid like molasses will flow less readily
Bw
■ ^■1
MWBL
Fiq. 123. — Determining viscosity of lubricating oil. (The Tide Water Oil Company.)
Fig. 124. — Determination of flash and fire point of lubricating oil. (The Tide Water OH
Company.)
than a liquid like gasoline and, consequently, is said to have a higher
viscosity. Oils are tested for viscosity by putting them in a container
called a viscosimeter, Fig. 123, and allowing them to flow through a small
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ENGINE LUBRICATION AND COOLING
109
opening. The oil that flows the fastest has the least viscosity. It is
necessary to use oil with less viscosity on some parts of an automobile
than on other parts. Tight fitting bearings should use oil with low vis-
cosity, while meshed gears should have semi-solid lubricants with high
viscosity because the pressure on the rubbing surface is very high.
Flash and Fire Point. — The flash point is the temperature at which,
if an oil be heated and a flame held over the surface as in Fig. 124, the
vapor rising from the oil will burst into flame, but will not continue to
burn. A thermometer is placed in the oil bath and the temperature taken
at this point. The fire test is a continuation of the flash point test; that
Fio. 125.— Cold teat for lubricating oil. (The Tide Water Oil Company.)
is, the temperature at which the vapor which rises from the oil will con-
tinue burning, and not merely flash for a second.
Cold Test. — The cold test, Fig. 125, indicates the temperature at which
the oil hardens, or becomes so stiff as not to flow. Good cylinder oil
should not become so stiff as to prevent its reaching the desired points
at zero temperature.
Acid Test. — A simple method to test for acid is to dissolve a little
of the oil in warm alcohol and then dip a piece of blue litmus paper in the
solution. If there is any acid present, the paper will turn red. The
litmus paper can be obtained at any drug store.
98. Gas Engine Cylinder Oil. — The oil to be used for cylinder lubrica-
tion must be of mineral derivation. Animal and vegetable oils decompose
and become gummy when used under cylinder conditions.
Cylinder oils are classified in three grades: light, medium, and heavy.
Light cylinder oil looks something like the ordinary machine oil, but
has a higher viscosity. The medium is somewhat heavier than the light,
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110 THE GASOLINE AUTOMOBILE
and might be compared to warm maple syrup. Light and medium oils
should be used only on engines which have close-fitting pistons. The
heavy oil is used in air-cooled engines and in engines that have loose
pistons or that become too hot to use the lighter grade of oil.
A gcjbd gas engine cylinder oil should have a flash point not under
400°F. and a fire test of over 500°F. so that it will not break down and give
off inflammable gases at low temperatures. Its viscosity should be such
that it will retain its body and not become so thin as to be worthless as a
lubricant at high temperatures. It should, however, be thin enough so as
to flow quickly over the cylinder walls. It should have sufficient body
to maintain a positive film between piston and cylinder, to prevent
leakage, yet should not be so heavy as to retard the free motion of the
piston and rings. It should also be free from acids or any form of
vegetable or animal matter and should not leave a carbon deposit in the
cylinder. The cold test must be low enough so that the oil will flow at a
low temperature. A large majority of the cylinder oils sold on the
market, under the well-known trade names, meet all of the necessary
requirements and may be safely used.
99. Systems of Engine Lubrication. — The purpose of a lubricating
system is to provide a film of lubricant between all rubbing, moving, and
bearing surfaces in order to prevent undue friction and wear on these
surfaces. The main and crank pins of the crankshaft turn in bearings
on the crank case and connecting rods and at the same time sustain the
force of the explosion in the cylinders. If the rubbing surfaces were not
separated by a film of oil, the bearings would become hot, would cause
excessive loss of power, and would probably seize the pins. Proper
lubrication will reduce the frictional loss to a minimum and will carry
away any excess heat which would cause the bearings to heat.
A similar condition exists in the cylinders where the pistons are
constantly moving up and down. A film of oil on the cylinder wall pre-
vents undue friction and excessive heating which might cause the pistons
to stick. This film can be maintained by a light oil as well as a heavy
oil, if other conditions are such that it can be used. The fuel conditions
have considerable to do with the lubrication of the cylinder, for, if any
liquid gets into or condenses in the cylinder, the lubricating oil will
be washed down into the crank case. This is particularly true when
heavy fuels, which are hard to vaporize, are used.
There are three principles used in providing suitable lubrication
for the various parts of the automobile engine. The oil may be placed
in the crank case and be splashed by the revolving cranks to the parts
to be lubricated, or a pump may be provided to pump the oil from the
bottom part of the crank case to a point above the part to be lubricated
to which the oil flows by gravity. A pump may also be used to pump
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ENGINE LUBRICATION AND COOLING
111
the oil under pressure to the parts to be lubricated. All the modern
lubricating systems are based upon one or a combination of the above
principles. In general, the systems may be classified under the following
headings:
1. Full splash.
2. Splash with circulating pump.
3. Pressure feed with splash.
4. Pressure or forced.
5. Full pressure or forced feed.
100. Full Splash System of Lubrication. — The full splash system is
used in the Ford engine, as shown in Fig. 126. The oil is poured directly
into the crank case through the breather pipe until it comes above the
lower oil cock. The level of the oil should be maintained somewhere
UPPER OIL-
COCK
LOWER OIL
COCK
CRANK CASE (XL TUBE
Fio. 126. — Full splash lubricating system on Ford car.
between the two oil cocks. The flywheel runs in the oil, picking some of
it up and throwing it off by centrifugal force. Some of the oil is caught
in the oil cup and is carried through the crank case oil tube indicated to
the front end of the crank case where it lubricates the timing gears. As
the oil flows back to the rear part of the crank case, it fills the small
wells in the crank case under each connecting rod. As the connecting
rods come around, a small spoon or dipper on the bottom scoops up the
oil, so that there is a regular shower of oil all the time. The pistons,
cylinder walls, and bearings are lubricated in this manner and the oil is
kept in continuous circulation. All parts of the clutch and transmission
are lubricated in the same manner as the engine.
The oil level should never get below the lower oil cock and never
above the upper oil cock. The level of the oil should never be tested
when the engine is running.
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THE GASOLINE AUTOMOBILE
101. Splash System with Circulating Pump. — A combination splash
and circulating pump feed system is used on the Dodge car, as illustrated
in Fig. 127. The oil is poured into the crank case through the breather
pipe on the left side of the engine. The oil is carried in the oil pan at the
bottom of the crank case. It is drawn through the oil strainer by the
oil pump which consists of two vanes and an impeller driven by a vertical
shaft* The oil is forced by the pump into the oil feed pipe which supplies
oil through holes into pockets from which the camshaft bearings are
lubricated. The crankshaft bearings are furnished with oil through oil
pockets which are in turn supplied from the camshaft bearing pockets
through passages cast in the cylinder block. Openings in the oil feed
„.0!L PRESSURE GAGE
OIL FEED PIPE
OIL LEVEL INDICATOR
/ BUTTON
CONNECTING ROD
OIL DIPPER
SEAR CASE
OtL OVERFLOW
OIL
WW POMP TO ENGINE
PUI1P TO ENGINE OIL TUBE
OIL TUBE
OIL STRAINER
OIL PAN
RESERVOIR
OIL PUTTP SHAFT
OIL STRAINER
Fig. 127. — Splash and. circulating pump lubricating system on Dodge car.
pipe allow oil to fill the four pockets in the oil pan from which the con-
necting rods, pistons and cylinder walls, cams, etc., are lubricated by
splash. All the overflow oil goes to the bottom of the oil pan from,
where it is drawn and recirculated by the oil pump. The oil gauge
on the dashboard indicates the pressure under which the oil is being
fed to the bearings. A slight pressure should be indicated on the gauge
when the car speed is from 15 to 25 miles per hour. Otherwise there
is trouble in the oiling system.
Some combination splash systems with circulating pump use the
pump merely for the purpose of circulating the oil from the oil pan to the
splash troughs below the connecting rods. The circulation is usually
through a sight feed on the dash so that the driver may know whether or
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ENGINE LUBRICATION AND COOLING
113
not the system is operating properly. This system as used on the Over-
land car is illustrated in Fig. 128. The oil reservoir is located in the
bottom of the crank case and is filled through the combination breather
pipe and oil filler on the right side of the engine. The glass gauge on the
side of the crank case close to the breather pipe indicates the oil level.
The oil pump, which is located in the rear of the crank case, is driven
from the camshaft. The oil is drawn from the base and, after passing
through a strainer, runs through a sight feed on the dash, from where it
runs into the troughs and is splashed onto the bearing surfaces.
Fio. 128. — Overland splash system with circulating pump.
The wrist pin is lubricated from the cylinder walls, through the
opening in the piston through which the wrist pin is inserted, as well
as through a slot cut into the connecting rod over the wrist pin bush-
ing. The lubricant circulates freely through the system as long as
the small wheel in the dash sight feed revolves. But as soon as the
wheel stops or the sight feed glass shows clear, this is an indication
that the oil supply is exhausted or that there is an obstruction in the
circulation of the oil. In some types of splash lubricating systems with
circulating pump, the sight feed on the dash is not provided, the oil
merely being circulated between the oil pan or pump and the troughs
below the connecting rods.
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THE GASOLINE AUTOMOBILE
102. Pressure Feed and Splash Lubrication. — The oil pump is some-
times used for furnishing oil under pressure to all of the parts to be
lubricated, with the exception of the pistons and cylinder walls. These
are lubricated by the oil thrown up from the overflow of the connecting
rod bearings. The pressure feed and splash system of lubrication used
on the Willys-Knight four-cylinder engine is shown in Fig. 129. The
sliding sleeves_and pistons are lubricated by the splash from the connect-
ing rods.
103. Pressure Feed System. — The pressure feed system as used on the
Cadillac Eight is shown in Fig. 130. A gear pump C located at the for-
ward end of the motor and driven from the crankshaft takes the oil up
Fia. 129. — Pressure feed and splash lubricating system on Willys-Knight engine.
from the oil pan A in the lower part of the crank case and forces it through
a reservoir pipe D running along the inside of the crank case. From pipe
D leads run to each of the main bearings. The crankshaft and webs
are drilled and oil is forced from the main bearings to the connecting rod
bearings through the drilled holes. The forward and rear main bearings
supply the rod bearings nearest them, while the center main bearing takes
care of the rod bearings on either side of it. The oil is then forced from
the main reservoir pipe up to the relief valve M , which maintains a uni-
form pressure above certain speeds, and overflows from this valve to a
pipe R running parallel with the camshaft but above it. Leads from
this latter pipe carry lubricating oil by gravity to the camshaft bearings
and front end chains. Pistons, cylinders, and piston pins are lubricated
by the oil thrown from the lower ends of the connecting rods.
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ENGINE LUBRICATION AND COOLING
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A gauge indicating the level of the oil is attached to the upper cover
of the crank case. Whenever the indicator reaches the space marked
fill, oil should be added until the indicator returns to full. A filling hole
is provided on the fanshaft housing just forward of the distributor. If
the hand on the pressure gauge on the cowl vibrates or returns to zero
on the dial when the engine is running, it indicates that the oil level is
very low. Should this occur through neglect to add oil at the proper
time, the engine should immediately be stopped and sufficient oil added
to bring the pointer up to the top of the gauge before the engine is again
started.
Fig. 130. — Pressure lubricating system used on Cadillac car.
The forced feed or pressure system as used by the Wisconsin Motor
Manufacturing Company is shown in Fig. 131. The oil is carried in an
independent chamber at the bottom of the crank case, and the connecting
rods are not allowed to dip into this, thus preventing the oil from being
whipped to a froth, and preserving its viscosity.
The oil is pumped by means of a gear pump, located at the lowest
point of the oil reservoir, into a main duct which is cast integral with the
crank case. From this duct, the oil is distributed to the main bearings
by means of other ducts, drilled into the crank webs. From the main
bearings it is forced through drilled passages to the connecting rod bear-
ings, and also a sufficient amount of oil is forced out of the ends of the
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THE GASOLINE AUTOMOBILE
bearings to lubricate the pistons, piston pins, and camshafts. A separate
lead runs directly over the timing gears, and all oil is thoroughly filtered
before it is pumped over again. An oil gauge indicates, by means of a
ball and float, the exact amount of oil contained in the reservoir. Dis-
tinct marks on the glass gauge show the high and low mark. If the oil
level is maintained between these
two levels no burnt oil smoke will
be emitted, and the spark plugs will
not be fouled.
The pressure of the oil increases
with the speed of the motor, so the
faster the engine is run the more oil
will be forced to it. The location of
the oil reservoir permits the proper
cooling of the oil, thus minimizing the
danger of burning out bearings.
104. Full Pressure or Forced
Feed System. — In this system, as
shown in Fig. 132, the oil is forced
by pressure to all parts to be lubri-
cated, including the wrist pins and
pistons. Oil is carried up the side of
| the connecting rods through a small
I pipe which is fed from the connect-
ing rod bearing on the crankshaft.
Besides lubricating the wrist pin,
the oil flows out onto the cylinder
walls and provides lubrication for
the pistojis.
106. Oil Pumps. — The oil pump
used may be either of the enclosed
gear type or of the piston type. A
gear type of oil pump is illustrated
in Fig. 133. The two gears are en-
closed in a close fitting housing and
are driven from the camshaft as in-
dicated. As the gears turn, the oil
is taken into the spaces between the
teeth and carried around to the out-
let where the action of the teeth meshing together squeezes the oil out of
the spaces and forces it to flow out of the pump. The oil pump is
driven either from the crankshaft of the engine or from the camshaft.
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ENGINE LUBRICATION AND COOLING
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The camshaft drive to the gear pump used on the Buick is illustrated in
Fig. 134.
The piston oil pump is very much like an ordinary bicycle pump in
principle. The oil is taken into the oil cylinder on the suction stroke of
Fig. 132. — Full pressure system of lubrication on Pierce Arrow car.
the oil piston, through a ball valve. On the return stroke of the piston,
the ball valve is closed and the oil is forced out into the oiling system.
Usually some method is provided for regulating the oil pressure when the
engine speed is high. This is done by putting a relief valve into the oil
coNwecrtoN ro
OtL Oi/TLCT
Pt/M*> HO&StMG
OIL tNLCT
Fio. 133. — Gear type of oil pump.
pipe line, or by regulating the stroke of the oil pump piston. The piston
pump and pressure regulating device used on the Hudson car is shown
in Fig. 136. The plunger piston is driven by the cam shown. The
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THE GASOLINE AUTOMOBILE
plunger is, however, under the control of another eccentric which is in
connection with the throttle of the engine. When the engine speed is
low, the eccentric holds the plunger in, permitting it to make a very-
short stroke when the cam comes around. As the engine speeds up,
the eccentric is shifted by opening the throttle. This permits a longer
stroke of the plunger.
106. Engine Lubrication in General. — The proper lubrication of the
automobile, especially the engine, is one of the most important items in
its operation. Poor lubrication may be the source of continual trouble
and expense, and may cause considerable damage to the engine parts,
while good lubrication permits the engine
to run efficiently without undue friction
or wear on its parts.
As mentioned before, only the best
lubricants obtainable should be used for
the lubrication of an automobile engine.
It is better to follow the manufacturer's
instructions in regard to the kind of oil to
use. The various automobile companies
run extensive tests and find out the best
oil for their particular type of engine. A
poor lubricant should never be used. " Its
first cost may be less but it is more ex-
pensive in the end, due to worn-out bear-
ings and scored cylinders.
Excess lubrication in the cylinders will
produce carbon deposits and dirty spark
plugs. It may also cause the piston rings
to gum up and stick. Excess lubrication
can be detected by the color of the ex-
haust which will have a bluish tinge, or
it may be detected by a sticky black
coating on the spark plugs.
When an engine has a tendency to lose compression, due to slightly
worn pistons and cylinders, it may be desirable to use a heavier lubricating
oil for the cylinder lubrication. This will maintain a better seal between
the pistons and the cylinder walls and will tend to prevent the loss of
compression.
107. Cylinder Cooling. — When an explosion occurs inside the cylinder
of a gas engine, the gases on the inside reach a temperature of from 2000°
to 3000°F. The walls of the cylinder are, of course, exposed to this
high heat and would get red hot very quickly if there was not some way
of keeping them cool. The polished surface upon which the piston slides
m^»
Co
^Spiral drive
from cam
shaft
Jkl
1
I
X
Gear oil
'pump
Pio. 134. — Oil pump drive on
Buick engine.
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ENGINE LUBRICATION AND COOLING
119
would be spoiled very quickly and lubrication prevented because of the
high temperature burning up the lubricating oil. The most common
way of keeping a cylinder cool is by the use of water. A metal jacket
surrounds the cylinder and provides a space for. the cooling water By
keeping a supply of water passing through this space, thevcylinder can
OH. RRtSSURC CALiGf
r. *l»vOwfr> WIO,
• •not. in my cowTitet in
ILOW g^CKO POkiT.Qfti MIOM lOltD POSITION
IK ntunvoiff
Fig. 135. — Piston type of oil pump on Hudson car.
be kept cool enough for the efficient operation of the engine. The cylin-
der head is also cast with a double wall, especially around the valves,
80 that these parts are also cooled by the circulating water.
There are two general methods of keeping the cylinders cool by the
use of circulating water or other cooling liquid. These are the ihermo-
typhon and the forced or pump circulation.
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120
THE GASOLINE AUTOMOBILE
108. Thermosyphon Cooling System. — In any type of cooling system
using water, the cylinders are surrounded by a water jacket through which
the water circulates. The top of the water space is connected by a rubber
hose to the top of the radiator, and the bottom of the water space to the
bottom of the radiator. The water, being heated by the engine cylinder,
goes to the radiator at the front of the car where it is cooled and returned
to the engine for use again.
The circulation of the water in the thermosyphon system is based on
the fact that cold water is heavier than hot water, and, consequently,
the water heated in the cylinder jackets rises and goes over into the top
part of the radiator. The water is cooled while passing down through
the radiator and flows from the lower portion of the radiator back to
the engine cylinder jackets. The rate at which the water circulates is
Fio. 136.— Overland thermosyphon cooling system.
increased or decreased with every increase or decrease in jacket tempera-
ture. Circulation is automatically maintained as long as the engine is
hot and there is enough water in the radiator to insure that the return
connection from the cylinder to the radiator also contains water. This
means that the radiator must be kept practically full all the time, or
there will be no circulation and the water will merely boil away. A fan
placed in front of the engine draws air through the radiator and cools
the water as it passes down through the radiator.
The thermosyphon cooling system o£ the Overland car is illustrated
in Fig. 136. The water enters the cylinder jackets A, and upon becoming
heated by the explosions within the cylinders, expands and, becoming
lighter than the cooler water, rises to the top. It then enters the pipe D
and passes into the radiator at F, where it is brought into contact with
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ENGINE LUBRICATION AND COOLING
121
a large cooling surface Ey in the form of the cellular radiator. On being
cooled and thereby contracting and becoming heavier, the water sinks
again to the bottom of the cooling system, to enter the cylinders once
more and to repeat its circulation. The cooling action is further in-
creased by a belt-driven f aji which draws air through the radiator spaces.
The cooling system on the Ford, Fig. 137, is also of the thermosyphon
type. The arrows indicate the path of the cooling water through the
engine cylinders and radiator.
Fio. 137. — Ford cooling system*
109. Pump or Forced System of Water Circulation. — The thermo-
syphon system of water circulation depends upon the temperature dif-
ference between the water in the cylinder jackets and in the radiator.
This circulation is not so definite or positive as in a pump system where
a water pump is used to maintain the water circulation. The pump is
usually driven by the engine, and, if the engine is running, the water is
circulating regardless of water temperatures. Figure 138 illustrates a
typical pump or forced system of water circulation. The centrifugal
pump placed at the front of the engine keeps the water in constant cir-
culation while the engine is running. From the pump the water is driven
into the cylinder water jacket, directly at the valve seats, where perfect
cooling is needed most. Here it absorbs the heat and goes on to the upper
cylinder connection and thence to the radiator. In the radiator D the
water percolates slowly down through many fine tubes F and is cooled
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122
THE GASOLINE AUTOMOBILE
by the air rushing between the fins surrounding the tubes and thence
returns to the pump. The fan on the front of the engine is driven from
the crankshaft and draws the air through the radiator, thus facilitating
the cooling operation. This radiator is a standard design of tubular
radiator. The pump, which is of the centrifugal type, requires no atten-
tion other than to see that it does not become choked by using dirty
water. There is a packing nut on the shaft which should be repacked
if the pump should ever leak around the shaft entrance. This can be
done very easily by turning off the packing nut, removing the old packing,
Fio. 138. — Pump or forced system of water circulation.
rewinding the shaft with a few inches of well graphited packing, and
tightening up the packing nut. The packing should be wound on in the
same direction as the nut is turned to tighten it.
110. Packard Cooling System. — The circulation in the cooling system
of the Packard Twin Six, Fig. 139, is maintained by a double impeller
centrifugal pump. This pump takes the water from the bottom of the
radiator and forces it through each of the cylinder block water jackets.
The outlet from the cylinder jackets is through the cored water passage
surrounding the gas intake header, which connects the cylinder blocks,
and then to the top of the radiator.
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ENGINE LUBRICATION AND COOLING
123
A thermostat, located at the top connection of the radiator, by-passes
the water coming from the cylinders to the inlet side of the pump until
it has reached the proper temperature for the efficient running of the
engine. When the water is cold, the thermostat valve is closed and the
by-pass to the water pump is open, allowing the water to circulate
through the cylinder jackets and back to the pump without going through
the radiator. As the water becomes heated, the expansion of the ther-
mostat opens the radiator valve and closes the by-pass to the pump,
making it necessary for all of the water to go through the radiator.
THERMOSTAT
INLET VALVE \
THERMOSTAT \
BY'PASS VALVE ^
.THERMOSTAT
HOUSING
I
RADIATOR MOTO-METER
CYUNDER INLET
MANIFOLD IS CORED
FOR WATER OUTLET^
FR0I1 CYUNDER \
JACKETS \ ,
. A
THERMOSTAT
RADIATOR
INLET TUBE
RADIATOR INLET
TUBE HOSE\
\
CYLINDER WATER
INLET MANIFOLD '
WATER PUMP---
RADIATOR TO
WATER PUMP
HOSE
radiator
'thermostat
by-pass con-
necting rad-
iator inlet &
outlet tube
Pio. 139. — Packard cooling system.
The radiator is of the flat ribbon tube type. A vent pipe extending
from the lower left corner of the radiator to the filler cap carries off any
surplus water or steam which may be formed.
111. Cadillac Cooling System. — The cooling system on the Cadillac
Eight, Fig. 140, is also of the forced circulating type. The radiator is of
the tubular and plate type, with a rotating fan mounted on the forward
end of the generator driving shaft, the latter being driven by a silent
chain from the camshaft. Each set of cylinders is cooled separately.
There are two centrifugal water pumps, one on each side of the forward
end of the engine. These are driven by a transverse shaft which is
driven by spiral gears from the crankshaft. Within each pump housing,
is a Sylphon thermostat, Fig. 141, which controls the flow of water be-
tween the radiator and the pump.
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124
THE GASOLINE AUTOMOBILE
When the temperature of the cooling water drops below a predeter-
mined temperature, the thermostats contract and close the valves be-
Fiq. 140.— Cooling system on Cadillac eight.
tween the pump and radiator. The water is then circulated only through
the cylinder blocks and the water jacket on the intake manifold. When
the thermostats are closed, none of the
water circulates through the radiator but
as the temperature of the water rises,
the thermostats expand, thereby gradually
opening the valves, permitting the water
to circulate through the radiator.
The advantage in this method of con-
trol is that, in starting with a cold en-
gine, the engine is brought to a point of
highest efficiency, in so far as temperature
is concerned, much more quickly than if
it were necessary to heat the entire
volume of water before reaching that
efficiency. With the usual water circulat-
ing system, the highest efficiency of the
engine is not reached in extremely cold
Fio. hi.— Cadillac water pump weather. An engine uses its gasoline
showing sylpbon thermostat. . ,. , ...
most economically when it is running
rather warm; but with a radiator which is adequate to prevent over-
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ENGINE LUBRICATION AND COOLING 125
heating in hot weather, the cooling is too great for best economy in ex-
tremely cold weather.
The thermostat is simply a small accordion shaped copper tube
containing a liquid which when heated changes to a gas and expands.
This thermostat is in connection with a valve B, Fig. 141, so that, when
it expands, it raises the valve from its seat, this valve controlling the
flow of water from the radiator to the pump. A by-pass C connects
with the water jacket of the engine, and, when the engine is started,
the water is naturally cold. Therefore, the thermostat is contracted
and its valve is seated. Thus the radiator water is shut off, the cir-
culation being simply to the water jackets of the cylinders from which
some water is by-passed through the carburetor jacket and pipe D and
some returns direct to the pump through hose C. There is only a small
part of the water circulating, and when this heats up, the thermostat
begins to expand and lifts its valve from its seat, permitting the water
in the radiator to flow into the system. This action continues back and
forth and keeps the water temperature nearly constant.
Cadillac Condenser. — The Cadillac system employs a condenser for
the purpose of preventing the loss of the cooling fluid by evaporation
when an alcohol solution is used. The condenser is placed under the
front floor boards and is connected to the overflow pipe of the radiator
by a pipe S, Fig. 140. The vapor given off from the hot cooling liquid
in the radiator passes through the overflow tube to the condenser where
it is condensed by coming into contact with the liquid. When the engine
is stopped, the liquid in the radiator contracts and the vapor condenses,
resulting in a vacuum in the top part of the radiator. This vacuum
allows the pressure of the atmosphere on vent V, Fig. 140, and this forces
the liquid out of the condenser back to the radiator. In order for the
condenser to operate properly, the radiator cap must make an air tight
joint.
112» Air Cooling. — The Franklin engine, shown in Fig. 142, uses an air
cooling system. The individual cylinders are each provided with 52
vertical steel flanges projecting from their periphery. The flanges on
each cylinder are surrounded by sheet aluminum jackets which form
passages for the air. These jackets or sleeves form a connection with a
sheet metal deck which divides, horizontally, the space under the
hood. The flywheel is provided with a number of curved blades so that
it has a blower effect whenever the engine is running. This forms a
partial vacuum which sucks air into the space underneath the hood
through the grilled opening in front. This air passes in uniform quan-
tities down through the individual jackets on each cylinder into the com-
partment below the engine deck and then out through the fan blades.
The fan is incorporated in the flywheel and driven directly by the engine,
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126
THE GASOLINE AUTOMOBILE
so a steady stream of fresh air is being continually drawn down over the
cylinders as long as the engine is running. As there is no cooling action
when the hood is raised, the engine should never be run for more than a
few minutes with the hood raised.
113. Radiators. — The cooling water after being heated in the water
jackets of the engine enters the radiator at the top, and, as it is cooled by
the air rushing through the openings in the radiator, it slowly descends
down through the radiator to the bottom. The rate and effectiveness of
the cooling action depend somewhat upon the type of radiator. There
are two general types of radiators, the tubular, and the cellular or honey-
comb.
Fia. 142. — Franklin air cooling system.
The tubular radiator consists of a series of tubes placed either hori-
zontally, vertically, or at an angle. The vertical placing of the tubes,
as shown in Fig. 138, is the usual method. Fins placed around the tubes
assist in carrying away the heat and cooling the water.
The cellular radiator consists of a number of short cells or tubes
arranged so that the water passes around the outside while the air rushes
through the inside. The cellular radiator is more costly to manufacture
but gives correspondingly more effective cooling, because the water flows
in thin flat streams instead of a comparatively large round stream as in
most of the tubular radiators. Some radiators are built which resemble
both the tubular and cellular types. Thin flat tubes run from the top to
the bottom of the radiator in a zigzag path, giving a cellular or honey-
comb appearance.
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ENGINE LUBRICATION AND COOLING
127
Radiator Shutters. — With the general use of automobiles in the winter
time, several schemes have been adopted to regulate the amount of air
drawn through the radiator by the. fan. Covers are used which partially
cover the front of the radiator and allow the cold outside air to pass
through only asmail partof the radiator. An;adjustable shutter, Fig. 143,
under the control of the driver is also employed for this purpose. When
the car is running, the shutter can be adjusted according to the outside
temperature, and, when the car is left standing, the shutter can be closed
to assist in keeping the cooling water warm enough to insure starting
and prevent freezing.
Fig. 143. — Adjustable shutter for radiator.
Fig. 144. — Boyce moto-meter.
114. Temperature Indicators. — If for any reason the cooling system
should not operate properly, it is very possible that the engine will
become overheated and may possibly stop. This usually results from a
loose or broken fan belt, leaky radiator or connections, obstructions in
radiator or connections, or from a defective pump. In turn, the cooling
system may be working properly, but the engine may overheat causing
the temperature of the cooling water to become excessive. In order
that the driver may be able to know just how the engine and cooling
system are working, a temperature indicator may be placed on the radia-
tor cap. Figure 144 illustrates the Boyce Moto-Meter which indicates at
all times the exact operating conditions of the engine and cooling system.
A temperature indicator is very desirable on a car because it will warn
the driver of coming trouble before serious damage results.
115. Cooling Solutions for Winter Use. — In climates where the tem-
perature does not go below a dangerous freezing point, the cooling medium
used is water; but in cold regions, where cars are run a good deal in the
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128 THE GASOLINE AUTOMOBILE
winter, it is necessary to use some kind of anti-freezing solution. The
ideal requirements for an anti-freezing compound are as follows:
1. It should have no harmful effect on any part of the circuit with
which it comes into contact.
2. It should be easily dissolved or combined with water.
3. It should be reasonably cheap.
4. It should not waste away by evaporation, that is, its boiling point
should be as high as that of water.
5. It should not deposit any foreign matter in the jackets or pipes.
The principal materials used are: (1) oil; (2) glycerine; (3) calcium
chloride; (4) alcohol; (5) mixture of alcohol and glycerine; (6) kerosene.
Oil has the advantage of a very high boiling point so it does not waste
away, but it has the disadvantage that it does not make a good mixture
with water. It will not absorb heat so rapidly as water and also has a
lower heat coefficient, that is, it takes less heat to raise the temperature
of a certain amount of oil one degree, than it does the same amount of
water. Oil cannot be used where there is any rubber in the circuit. The
oil causes the rubber to deteriorate rapidly.
The disadvantages of using glycerine are similar to those of oil,
but the most important is sure destruction to the rubber connection.
Glycerine is also liable to contain free acids, and is quite expensive.
Calcium chloride jnakes a very good solution with water, the freezing
point depending upon the proportion used. The general solution is to
use 5 lb. of the salt to 1 gal. of water. This solution will stand 39°
below zero before freezing. It has the disadvantage of being very apt
to cause electrolytic action where two metals are* joined together. Cal-
cium chloride is derived from hydrochloric acid, and is liable to contain
free acids, which attack metal very rapidly. Calcium chloride has the
same appearance as chloride of lime, but has a somewhat different chemi-
cal composition. Only pure calcium chloride should ever be used. The
commercial chloride of lime sets up electrolytic action. The solution
may be tested for acid by dipping a piece of blue litmus paper in it. If
there is any acid present, the paper will turn red. As the water is evapo-
rated in the radiator, there will be a crust formed on the inside of the
jacket, and also in the pipes. This crust has a tendency to clog up the
system and prevent circulation. The rate at which these deposits
occur depends on the strength of the solution.
Denatured alcohol is the best substance to use as a non-freezing
solution, as it has no destructive action whatever on either metal or
rubber, makes no deposits, and never causes electrolytic action. A solu-
tion of 50 per cent, water and 50 per cent, alcohol will stand about
32° below zero. The only disadvantage is that it evaporates more
readily than the water, so that when adding new solution, more alcohol
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ENGINE LUBRICATION AND COOLING
129
than water must be added in order to keep the solution of the same
strength. The combination of alcohol, glycerine, and water seems to
give very good results. In this combination, equal parts of alcohol and
glycerine are used. The alcohol has a tendency to overcome the de-
structive action of the glycerine on the rubber connections, and the
glycerine keeps the alcohol from evaporating too rapidly. The freezing
point depends on the strength of the solution. A solution of 60 per cent,
water and 20 per cent, each of alcohol and glycerine, freezes at 24° below
zero. The proportions must be governed by the locality in which
they are used.
There are also numerous anti-freezing compounds on the market.
These are generally put up from some of the materials mentioned.
In the following tables are shown the temperatures at which some of
the well-known anti-freezing solutions will freeze. The different localities
and different altitudes require different solutions. Every person should
be able to select a solution in the right proportion, to avoid having any
trouble in the coldest possible weather likely to be experienced in the
home location.
Freezing Points of Calcium Chloride Solutions
Per cent, by volume of calcium chloride
Specific gravity of solution
Freezing point
10
1.085
22°F.
15
1.131
13°F.
20
1.119
0°F.
22
1.200
- 9°F.
24
1.219
-18°F.
26
1.242
-28°F.
28
1.268
-42°F.
The specific gravity is given to be used as a check on the proportions.
Freezing Points of Denatured Alcohol Mixed with Water
Per cent, by volume of alcohol
Specific gravity of solution
Freezing point
10
0.988
24°F.
20
0.975
14°F.
30
0.964
- 1°F.
40
0.954
-20°F.
50
0.933
-32°F.
60
0.913
-45°F.
70
0.897
-57°F.
If wood alcohol be used instead of denatured alcohol, slightly lower temperatures
can be reached with the same proportions of alcohol and water.
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130 THE GASOLINE AUTOMOBILE
Freezing Points or Alcohol and Glycerine Mixed with Water
Alcohol and glycerine, per cent.
Water, per
cent.
Freezing point
15
85
20°F.
25
75
8°F.
30
70
- 5°F.
35
65
-18°F.
40
60
-24°F.
45
55
-30°F.
50
50
-33°F.
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CHAPTER VI
PRINCIPLES OF ELECTRICITY AND MAGNETISM
116. Electricity. — Probably no other factcr has played a more im-
portant part in making possible the modern gasoline automobile with its
four-, six-, eight-, or twelve-cylinder engine, than has electricity in its
many applications. It may be said that the development of the auto-
mobile power planth as been controlled largely by the development of
the electrical ignition equipment upon which the engine depends for its
operation. Besides using electricity for igniting the fuel charge within
the engine cylinders, it is also called upon to start the engine, furnish the
light, operate the horn and, in some instances, to shift the gears of the
transmission. The indispensable usefulness of electricity in the auto-
mobile field is evidenced by the fact that all makes of passenger auto-
mobiles, as well as many trucks and tractors, are now completely equipped
with an electric starting, lighting, and ignition system.
Since the operation of the automobile depends so greatly on the
successful operation of its electrical equipment, it is very necessary
to have a clear understanding of the fundamental electrical and electro-
magnetic principles governing the construction and operation of the
electrical equipment used, in order that it may be operated and repaired
successfully.
The exact nature of electricity is not known; but its effects, the
laws governing its action, and the methods of controlling and using it in
doing various kinds of work are well understood. Two general methods
are employed in generating electrical energy on the automobile. One
of these is chemical action, which is the fundamental principle of the
battery, while the other is the conversion of mechanical energy into
electrical energy through electromagnetic induction, the method em-
ployed in the magneto and generator.
117. Conductors and Non-conductors. — All substances conduct elec-
tricity to some extent; some much better than others. There is no
known substance which does not offer some resistance to the flow of
electrical current through it. Substances such as silver, copper, etc.,
which offer a comparatively low resistance are known as conductors,
while substances such as porcelain, glass, fiber, etc., which offer a high
resistance to the passage of electrical current are known as non-conductors
or insulators. A liquid which offers a comparatively low resistance is
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132
THE GASOLINE AUTOMOBILE
known as an electrolyte, while a liquid that offers a high' resistance is
termed a non-electrolyte.
118. Hydraulic Analogy of Electric Current. — An electric current
flowing through a wire may be compared to the flow of water through
a pipe line. As the water flows through the pipe due to pressure from
a pump or a difference in water level, such as from A to B in Fig. 145,
— XJ
^Jtr^=-
VALVEj
Fig. 145. — Hydraulic analogy of electrical current.
so electrical current will flow through a conductor due to an electrical
pressure or potential created by a battery or mechanically driven gen-
erator. The current flows through the circuit from the high potential
or positive (+) terminal to the low potential or negative (— ) terminal,
as shown by the arrows in Fig. 146. In the case of the water, however,
the pressure causing it to flow is measured in pounds per square inch
and the rate of flow in gallons
per unit of time, while in the
electrical circuit the pressure or
electromotive force is measured in
units called volts, and the rate of
current flow in amperes.
119. Resistance. — The oppo-
sition that a substance offers to
the passage of an electric current
through it is called its resistance,
and the unit of this electrical re-
sistance is called the ohm. The
ohm may be defined as the resis-
tance offered by a circuit to 1 ampere of current flowing under a pres-
sure of 1 volt. Resistance of a circuit may be compared to the friction
which a pipe offers to the flow of a liquid, in that, electrical resistance
depends upon the size, length, material, and temperature of the wire, just
as the flow of any liquid is resisted by friction which in turn depends
upon the size, length, and shape of the conducting pipe as well as upon
the temperature of the liquid. Thus the resistance of a conductor or
wire will decrease by increasing its cross sectional area, and will in-
crease by simply increasing its length. In both cases, the current which
Fig. 146. — Battery electrical circuit.
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ELECTRICITY AND MAGNETISM 133
will flow at a certain voltage will increase or decrease as the resistance
changes. In fact, the resistance is directly proportional to the length
of a conductor and inversely proportional to its cross sectional area.
This is true only in case the temperature does not change, since it has
been found that in the case of most metal conductors an increase in
temperature is accompanied by an increase in resistance, while in the
case of insulating materials, carbon and various electrolytic solutions,
an increase in temperature is accompanied by a decrease in resistance.
120. Relation between Current, Voltage, and Resistance. — Ohm dis-
covered that in the case of circuits which carry current continuously in one
direction (known as direct-current circuits), a definite relation exists
between the current flowing, the voltage, and the resistance of the
circuit. This relation is known as Ohm's law, namely: The electric
AMMETER
TERMINALS--^ A^ i,
CONNECTED TO ( VWOLTMETER L
SOURCE OF v - * '
CURRENT SUPPLY^
Fig. 147. — Method of connecting ammeter and voltmeter on electrical circuit.
current in a conductor equals the voltage applied to the conductor divided by
the resistance of the conductor. This law may be simply stated: Current
= voltage -s- resistance.
Or, stating the same thing in another way:
(1) Amperes = Volts -*- Ohms
or
(2) Volts = Amperes X Ohms
or
(3) Ohms = Volts -£- Amperes
These rules may also be expressed in more convenient formulas:
E
Namely: (1) To find Current, I = ^ • (2) To find Voltage, E = I X R.
E
(3) To find Resistancef R = -j in which J = the current in amperes, E =
the voltage, and R =» the resistance in ohms.
Thus if two things are known regarding a circuit such as, the voltage
and resistance, or the current and resistance, or the voltage and current
the exact relation between voltage, current, and resistance can be readily
calculated by applying the proper formula.
The voltage and current in a circuit can be readily measured by
connecting a voltmeter and ammeter as shown in Fig. 147. The voltmeter
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134 THE GASOLINE AUTOMOBILE
is an instrument for measuring the electrical pressure in volts and is
connected across the source of current supply which in Fig. 147 is repre-
sented by terminals A (+) and B (— ). The ammeter is an instrument
for measuring the current flow in amperes and is connected in the circuit
so that all the current flowing in the circuit passes through the instru-
ment. As there is no instrument for measuring directly the electrical
resistance of a circuit, it must be calculated by first measuring the voltage
and current and dividing the voltage in volts by the current in amperes as
in formula (3). Consequently, if a wire consists of such material, size,
length, and temperature as to offer 1 ohm resistance, the voltage re-
quired to force 1 ampere through it must be 1 volt. The volt or unit of
electrical pressure, then, may be defined as the pressure required to force
one ampere of current through a circuit having one ohm resistance.
121 Electrical Power. — The unit of electrical power is the watt. It is
defined as the rate at which work is performed by 1 ampere of current
flowing through a circuit under 1 volt pressure. Expressing this as a
formula:
(4) P = I X E
in which J = the current in amperes, E = the voltage, in volts, and P =
the power in watts.
As an example: The electrical energy or work required of a 6 volt
battery in supplying a current of 2 amperes to the primary ignition cir-
cuit would be 6 X 2 = 12 watts. The watt is too small a unit for con-
venient use in many cases so that the kilowatt (kw.) or 1000 watts is
frequently used.
Other factors which the reader should become familiar with are:
1 Horse Power (Hp.) = 746 watts or .746 kilowatt.
1 kilowatt = 1.34 Horse Power.
1 kilowatt of power used for 1 hour = 1 kilowatt-hour.
1 ampere of current for 1 hour = 1 ampere-hour.
122. Effects of Electric Current. — Experiments have shown that
electric current in flowing through certain circuits produces various
physical, chemical, and magnetic changes or effects. On the automobile,
these effects include (1) heat and light, as witnessed in the glow of the
lamp filaments; (2) chemical action, which is the principle of the storage
battery; and (3) magnetism, upon which the induction coil, magneto,
generator, and starting motor depend for their operation.
Heat is developed in any conductor through which electricity flows.
The temperature of the conductor, consequently, is raised. The heat
represents the loss due to the overcoming of the resistance by the current.
The amount of heat developed is often very small and is not noticeable.
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ELECTRICITY AND MAGNETISM
135
148. — Chemical effect of electrical current.
Fuses burn Out because of the heat developed in them by the current.
When the current becomes excessive the fuse wire melts and opens the
circuit, protecting it from possible damage. Incandescent lamps produce
light because their filaments are heated by the passage of an electric
current.
The chemical action due to electric current may be illustrated, as in
Fig. 148, by submerging the ends of two wires, connected to battery
terminals, in a glass of water in which a little salt has been dissolved.
The current in passing through
the water will liberate a gas in
the form of fine bubbles which
it will be noticed rise particu- /
larly around the negative ter- >
minaL This simple test is very
valuable to remember as a means
of determining the positive and
negative of two direct-current
leads. It is also valuable in
distinguishing between alternating and direct current, since alternating
current will cause bubbles to collect equally around both terminals.
The magnetic effect of electric current can be readily noticed by send-
ing battery current through an insulated wire wound on an iron bar as
shown in Fig. 149, and noting the attraction which the iron will then
have for other pieces of iron. The iron bar is now said to contain magnet-
ism which, as will be shown
later, has a definite rela-
tion to the direction of the
current.
123. The Dry Cell.—
The first necessary part of
an electric ignition system
is a source of current. For
this purpose either a bat-
tery, a generator, or a mag-
neto can be used. In a battery ignition system, the current is supplied
by either dry batteries or a storage battery in combination with a gener-
ator that is driven by the engine.
The dry cell has been a common source of current for ignition pur-
poses but is now being supplanted by the storage battery. The dry cell
is especially adaptable for ignition systems of the open circuit type such
as certain models of the Atwater-Kent system where the current demand
is small. Figure 150 shows a section of a commercial dry cell. It con-
sists of a cylindrical zinc shell or can around the inside of which has been
BATTER
IRON
C^RB
mm*
BLECTRO-MAONET
Fio. 149. — Magnetic effect of electrical current.
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136
THE GASOLINE AUTOMOBILE
placed a piece of absorbent paper saturated with salammoniac and zinc
chloride dissolved in water. The zinc shell forms the negative terminal
of the battery, and the carbon element down through the center of the
cell forms the positive .terminal. The space between the absorbent paper
and the carbon is filled with a mixture of powdered carbon and manganese
dioxide which acts as a. depolarizing agent. Polarization refers to the
accumulation of hydrogen gas bubbles around the carbon or positive ter-
minal of the cell upon rapid current discharge. The gas tends to insulate
the carbon stick, thereby increasing the internal resistance and diminish-
ing the current output. The voltage of a dry cell is about 1.5 volts.
The maximum current or amperage of a new cell ranges from 20 to 35
amperes, depending upon the size of the cell and the temperature. A
dry cell giving more than 25 to 30 amperes will probably polarize rapidly.
Nearly all American dry cells are 2}i in. in diameter and 6 in. high. The
Fig. 160. — The dry cell.
top is sealed with a special compound to make it water-tight. The entire
cell, except the top, is wrapped with pasteboard to prevent the zinc
making contact with other zinc cans in the set. The dry ceU always
gives out direct current. Its capacity and its life depend on the way it is
used, both being greater when it is used intermittently. Cells not in use
should be stored in a cool dry place to prevent rapid deterioration.
124. The Storage Battery. — Although the storage battery will be dis-
cussed in Chapter IX, a brief description is given here in order to bring
out clearly its function as a source of electrical energy on the automobile.
A storage cell, Fig. 151, consists of two sets of lead plates, positive and
negative, placed in an acid proof jar containing a solution of sulphuric
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ELECTRICITY AND MAGNETISM
137
acid and water. Each plate consists of a grid or framework composed of
lead and antimony, the openings of which are pasted full of a lead com-
pound, known as active material. Two or more plates of the same kind
connected to a common terminal form a group.
In the positive group, the active material is lead peroxide, character-
ized by its chocolate brown color, while in the plates of the negative
group it consists of finely divided sponge lead (pure lead) and is greyish
in color. The positive and negative groups are placed in the cell so that
the positive and negative plates alternate and are insulated from each
other by separators of specially treated wood or threaded rubber. By
passing direct current through the cell, sending it in at the positive and out
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Fig. 151. — Section of storage cell.
at the negative terminals, the plates undergo an electrochemical change
known as charging. When the battery is used or discharged the chemical
change is reversed and the plates tend to return to their original state,
giving off current as they do so. The current thus produced is a direct
current. It leaves the battery at the positive terminal and returns to the
negative. A single storage cell consists of one positive and one negative
set of plates, and gives, when fully charged, a pressure of about 2 volts.
Its current capacity depends upon the size and number of plates in the
cell.
126. Wiring of Ignition Batteries. — When current for ignition is sup-
plied by a storage battery the voltage may be either 6 or 12 volts. This
voltage is fixed by the design of the starting and lighting system which is
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138
THE GASOLINE AUTOMOBILE
usually of the sarpe voltage as the ignition and which operates off of the
same battery. The battery may vary in size from 60 to 130 ampere-hour
capacity, depending upon the requirements of the starting and lighting
system. Since one storage cell gives only 2 volts, in a 6 volt battery the
3
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12 Volts
1
Fio. 152. — Cell connections for a six
volt storage battery.
Fio. 153. — Cell connections for a
twelve volt storage battery.
proper voltage is obtained by connecting 3 cells in series, that is, con-
necting the Positive (+) terminal of one cell to the Negative (— ) of the
next as shown in Fig. 152. In like manner, a 12 volt storage battery
must have 6 cells connected in series as in Fig. 153.
fit^y^y®^ &&Q
S Dry cells in series
Fio. 154.
S Dry cells in parallel
Fio. 155.
When dry cells are used for ignition, two methods of connecting
several cells may be resorted to in order to raise the voltage and amperage
to the proper amount, namely, through series or parallel connection. The
series method of connection is shown in Fig. 154 in which the carbon or
Positive of one cell is connected to the zinc
or Negative of the next, leaving one carbon
and one zinc free for connection. Thus
the current has to pass through the entire
set of cells to complete its circuit. This
method increases the voltage as many
times as there are cells. The five cells of
Fig. 154 each give about 1.5 volts and
will, when connected in series, furnish a
current at 5 X 1.5, or 1% volts pressure. The current output is equal
to the current of one cell, or about 20 amperes. If all the carbons are
connected and all the zincs fastened together, as shown in Fig. 155,
/S cells in multiple scries arronyement
Fio. 156.
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ELECTRICITY AND MAGNETISM 139
the connection is known as parallel. The resultant voltage equals the
voltage of one cell, and the current output equals the current output of
one cell mutiplied by the total number of cells. For example, the current
output of five cells connected in parallel would be 5 X 20 or 100 amperes
and the voltage would be 1J^ volts. Therefore, to increase voltage, con-
nect the cells in series, and to increase current output connect them in
parallel.
Where the current demand is small or not continuous, five cells
connected in series may be used. This arrangement gives 7}£ volts and
20 amperes and is suitable for single cylinder engines or for starting en-
gines of two or more cylinders where a magneto is used after the engine
is in operation. It is also suitable for battery ignition systems of the
open circuit type, such as certain models of the Atwater-Kent.
When the amount of current required is great and a storage battery
is not available, the multiple series connection may be used. It is suitable
for engines of two or more cylinders and for continuous service. This
arrangement consists of parallel groups of as many cells in a series as may
be required for the service. Figure 156 shows an arrangement with three
parallel sets, each having five cells connected in series. This arrange-
ment provides for an amperage of about 60 at 7}>i volts.
126. Magnetism. — That property of certain substances to attract
and repel other materials is called magnetism. It is not known precisely
what magnetism is any more than the exact nature of electricity is known.
But the rules governing it have been well established. Electricity and
magnetism are entirely different although they are very closely related.
127. Natural and Artificial Magnets. — Magnetism and its properties
were first made known to man near the town of Magnesia, in Asia, where
an iron ore was found that possessed a remarkably attractive power for
iron. This attractive power was called magnetism, and a piece of ore
having this power was termed a magnet. The ore itself has since been
named magnetite and lodestone and is the only form of natural magnet
known. It is not in such form as to be of commercial value, consequently
the magnets which will be considered are manufactured and are known
as artificial magnets.
128. Magnetic and Non-magnetic Metals. — Only certain substances,
chiefly iron and steel or alloys containing the same, show magnetic prop-
erties. Metals such as brass, copper, aluminum, or zinc which do not
contain iron and which are not susceptible to magnetism are called non-
magnetic metals.
Soft iron, after being magnetized, loses its magnetism readily as soon
as the magnetizing force is removed, and is called a temporary magnet.
A bar of hardened steel after being magnetized will, with proper treatment,
remain magnetized indefinitely and is called a permanent magnet. For
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140
THE GASOLINE AUTOMOBILE
this reason, temporary magnets, such as used in the cores of induction
coils, are made of soft iron — usually a bundle of soft iron wire — while per-
manent magnets, such as the magnets of a magneto, are made of either
hardened nickel, chrome, or tungsten steel.
129. The Poles of a Magnet — Certain parts of a magnet possess the
power of attracting iron to a much greater extent than other parts. These
parts are called the poles. In a bar
magnet the strength is greatest at the
ends, consequently the ends form the
poles. These poles are designated
North and South according to their
magnetic influence on other mag-
nets, and according to the direction
of magnetism.
It is generally understood that
magnetism acts in the nature of a
stream or current. This flow of mag-
netism is termed magnetic flux and
is conventionally represented by lines
of force which always flow out of the
North pole of a magnet and around
into the South pole, forming a complete circuit. The reason for this is
readily seen by placing a piece of paper over a bar magnet and sprin-
kling iron filings over the paper. The action of the magnetic force will
arrange the filings in lines running from one end of the magnet around to
Fig. 157. — Field of a bar magnet as
shown by iron filings.
Fig. 158. — Lines of force around bar and horseshoe magnets.
the other end as shown in Fig. 157. These lines of force may also be
illustrated graphically as shown in Fig. 158.
When two magnets are brought together, it is found that the North
pole of one attracts the South pole of the other, and that two like poles,
either North and North or South and South, repel each other. Magnetic
attraction and repulsion are shown by dipping two common magneto
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ELECTRICITY AND MAGNETISM
141
magnets in iron filings and noting the formation of the filings when the
poles of the two magnets are brought together. With the North and
South poles brought together, as in Fig. 159, the iron filings will form in
metallic strings between the poles thus showing magnetic attraction.
With the like poles brought together, as in Fig. 160, the filings will have
jMz^k-
^
Fio. 159. — Magnetic attraction of
unlike poles.
Fig. 160. — Magnetic repulsion of like
poles.
the appearance of two jets of water being forced against each other,
and will show repulsion. In each case the iron filings plainly indicate
the path of the magnetic circuit which is flowing within the magnet
from the South (S) to the North (N) pole and through the space between
the poles from the North (N) to the South (S).
Pocket
Compass
.,--^j^
Fig. 161. — Use of compass to determine magnetic polarity.
130. The Magnetic Field. — The zone surrounding a magnet through
which the magnetism flows from the North pole to the South pole is
known as its magnetic field. The strength of this field depends upon the
number of magnetic lines of force per square inch of the magnet poles and
is usually measured in pounds pull per unit area of the pole.
The polarity of a magnet and the direction of its magnetic field
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142 THE GASOLINE AUTOMOBILE
may be determined by using a compass as shown in Fig. 161. The North
end of the compass needle (the end which naturally points toward the
geographical North pole) will always point in the direction of the magnetic
field which is towards the South pole of the magnet. Likewise, the
South end of the compass needle will point towards the North pole of
the magnet.
131. Electromagnetism. — Magnetism which is produced by an electric
current is called electromagnetism. Experiments show that a wire or any
(A) (B) SIDE VIEW (O
LEFT END VIEW (CURRENT FU0WM6 FROM RIGHT END VIEW
CURRENT 3XNG IN) LEFT TO RI6HT) CURRENT 60M6 OUT
Fjq. 162. — Magnetic lines of force about a straight conductor carrying current.
other form of conductor which carries an electric current will have a magnetic
field set up around it in a right-handed direction to the current and proper"
tional in strength to the amount of current flowing. This fact constitutes
the basis for the relation between electricity and magnetism. The mag-
netic field thus produced is arranged in concentric circles around the
wire, as in Fig. 162, and, like the field of a magnet, its direction can be
determined by a pocket compass. The magnetic needle, if held above
or below a wire carrying a direct current, will turn crosswise of the wire,
Fig. 163. — Deflection of a compass needle when near a conductor carrying a current.
as in Fig. 163, with the North end of the compass pointing around the
wire in the direction of the magnetic field. Thus by determining the
direction of magnetic field around the wire, the direction of current
flowing in the wire may also be determined.
If the wire is coiled into a loop, as in Fig. 164, it will be found that
the lines of force all enter the same face of the loop and come out of
the other face. If two loops are placed close together, as in Fig. 165, the
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ELECTRICITY AND MAGNETISM
143
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lines of force will join and go around the two wires together instead of
around each one alone. The same is also true of the lines of force sur-
rounding two parallel wires placed
close together in which both wires
are carrying current in the same
direction. If a number of turns of
insulated wire are wound into a coil
or solenoid, as in Fig. 136, nearly
all the lines of force will enter one
end of the coil, pass through it, leave
the opposite end, and return outside
of the coil to the starting point.
Thus a solenoid or coil carrying an
electric current has the same char-
acter of magnetic field as a bar mag- Flo 164._Magnetic field produced by
net having a North pole where the current in a single loop.
#^- *-. \H
Piq. 165. — Magnetic lines of force around two adjoining loops carrying current in the same
direction.
lines of force leave the coil and a South pole where the lines of force
enter the coil, and may be considered an electromagnet.
Fio. 166. — Lines of force through a coil or solenoid.
132. The Electromagnet. — An electromagnet made as just described
is not very strong, but may be made so by inserting a core of soft iron or
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144
THE GASOLINE AUTOMOBILE
*[*•&-* ^5 XV»#
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steel, as in Fig. 167. The iron has the property of conducting magnetic
lines much more readily than air; hence, a solenoid with an iron core
will have a much greater strength than a simple solenoid without a core.
The strength of the electromagnet may also be increased by in-
creasing either the amount of current flowing through the winding
or the number of turns in the coil, or both. In fact, the magnetic pull
of the core will depend not only on the size and length of the core but
on the number of amperes multiplied by the number of turns in the wind-
^•— -^^.^ ln& or the total number of
ampere-turns producing the
magnetism. Thus, in Pig.
167, if the coil consists of 10
turns of wire through which
a current of 8 amperes is
flowing the magnetic pull of
the core will be due to 10 X
8 or 80 ampere-turns.
133. To Determine the Polarity of an Electromagnet — A simple,
method for determining the polarity of an electromagnet, if the direction
of current is known, is to grasp the coil in the right hand with the fingers
pointing around the core in the same direction as the current flowing in
the winding. With the hand in this position, the thumb will naturally
point in the direction of the magnetic lines of force or along the core to
the North pole.
The polarity of such an electromagnet may also be quickly determined
by holding a compass near its poles. The North end of the needle will
point to the South pole of the magnet as already illustrated in Fig. 161.
Fig. 167. — The electromagnet.
Direction of Current
Direction of
Magnetic Field
m$z
Fig. 168. — Relation between direction of current and magnetic field.
134. Electromagnetic Induction* — It was found in the preceding
paragraphs that a current flowing in a conductor produced a magnetic
field which was set up around the conductor in a right-handed direction
to the flow of current, as shown in Fig. 162. It will also be found that
if a magnetic field is set up around a conductor an electric current
will be caused to flow in the conductor and that the same relation exists
between the direction of current flow and the magnetic field. This
relation is shown very clearly in Fig. 168, in which the forward travel
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ELECTRICITY AND MAGNETISM
145
of the screw represents the direction of current, and the rotation of the
screwdriver, the direction of magnetism.
The process of generating a current in this manner is known as
induction, and the current thus produced is called an induced current.
If the current is generated by magnetism alternating in direction, the
induced current will also be alternating in direction, with as many
reversals through the wire per second, as there are reversals of magnetism.
Such a current is dialled alternating current and is usually abbreviated A.C.
A magnetic field may be set up around a wire by either cutting
a magnetic field with a wire, such as rotating an armature of a magneto
or generator in a magnetic field, or by cutting the wire or coil of wire
Fig. 169. — Principle of electromagnetic induction.
with a rapidly moving magnetic field as found in the inductor type
magneto and induction coil.
The method by which a magnetic field is set up around a conductor
and the relative direction of the induced current are illustrated by Fig.
169 A, B, and C, in which N and S represent North and South poles of
a magnet and W a wire cutting through the magnetic field between N
and S in a downward direction. The magnetic lines of force between N
and S cause an attraction between the two poles, like that of many
rubber bands under tension. The rubber bands if intercepted by a
moving wire will be crowded ahead as indicated in Fig. 169B. In a
similar way, the magnetic lines of force will be distorted by the moving
wire as shown in Fig, 169C It will be noted that the distorted lines of
9
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146
THE GASOLINE AUTOMOBILE
force crowding ahead of the moving conductor or wire create a field of
greater intensity on one side of the conductor than on the other. This
will have the effect of setting up a magnetic whirl around the conductor
in an anti-clockwise direction thereby inducing a voltage and current
in the conductor as indicated by the arrow. This whirl of magnetic
lines may be likened in direction to a whirlpool caused by water turning
Whirlpool.
Fig. 170. — Water analogy of magnetic whirl
around a conductor.
Fio. 171. — Magnetic lines of
force cutting a conductor.
DIRECTION OF
INDUCEDiCURRENT
MOTION OF
CONDUCTION
a sharp bend in a creek, as in Fig. 170, in which the water corresponds
to the magnetic lines of force.
In this example, the field was considered stationary and the wire
movable. If the wire should be stationary and the magnetic lines made
to cut the wire as in Fig. 171, the effect would be the same, resulting in
a current, and voltage being induced in the wire. In either case, the
current will be set up in the wire in a direction which depends upon the
direction of the magnetic lines between
the poles and upon the direction at
which the wire cuts the magnetic lines
of force. The voltage thus produced
is proportional in strength to the re-
sistance of the wire, to the strength
of the magnetic field, and to the speed
at which the magnetic lines of force
are cut.
135. The Right-hand Rule. — An
easy way to determine the relation be-
tween the induced current, the direction
of magnetism, and the motion of the wire through the magnetic field,
is by holding the thumb and first two fingers of the right hand at right
angles as shown in Fig. 172. If the thumb is made to point in the
direction of the magnetic field, and the second finger in a direction cor-
responding to the relative motion of the conductor, the first finger will
point along the conductor in the direction of the induced current.
ERECTION OF
1 MAGNETISM
Fio. 172. — Right-hand three-finger
rule for determining direction of in-
duced current.
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CHAPTER VII
BATTERY IGNITION SYSTEMS
136. Automobile Ignition. — All automobile engines depend upon some
form of electric ignition for igniting the fuel charge within the engine
cylinders by means of a spark. To accomplish this, two methods of
electric ignition may be used; namely, the make-and-break or the jump-
spark method.
In the make-and-break method of ignition, an electric current of low
voltage, furnished either by a battery or a magneto, is made and broken
by a contact mechanism known as an igniter, the contact points of which
extend into the combustion chamber of the engine cylinder. The spark
for ignition occurs at the instant the contact opens, and is caused by the
sudden stoppage of the electric current in combination with the action
of a coil connected in the circuit.
In the jump-spark ignition system, current is derived either from a
battery or a magneto, but is first transformed from low voltage to high
voltage, whereupon it is made to jump the points of a spark plug inside
the cylinder, the spark thus created setting fire to the combustible gases.
The make-and-break method of ignition on the automobile has given
way entirely to the jump-spark method on account of the greater sim-
plicity and many advantages of the latter, but, owing to the similarity
in the action of the ignition coils used in both systems, the operation of
the make-and-break coil should be well understood.
137. The Low Tension Coil for Make-and-break Ignition. — The coil
used for make-and-break ignition is very simple in construction in that
it consists of a single winding of insulated wire wound on a soft iron core
as shown in Fig. 173. The core is usually made of a bundle of soft iron
wire so that it will magnetize and demagnetize rapidly. Such a coil is
usually termed a kick coil for the reason that, if a current through the
coil is suddenly interrupted by breaking the circuit, a flashy spark of
considerable intensity or kick will occur at the point of breaking. The
spark thus produced occurs between the igniter points inside the cylinder
and is made use of in igniting the fuel charge.
The large flashy spark which occurs at the point of current interrup-
tion is due to the induction of a voltage and a current in the winding
of the coil by the collapsing lines of force when the circuit is broken.
A study of Fig. 173 will show that the magnetic lines of force, upon the
147
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148
THE GASOLINE AUTOMOBILE
demagnetizing of the core, will move rapidly toward- the core and cut
each turn of wire much the same as in Fig. 171. This cutting of the wire
by the lines of force will set up a whirl of magnetic lines around each turn
of wire and will induce a voltage in the coil in the same direction as the
original current from the batteries. This induced or kick voltage of the
coil is in series with the battery voltage and often reaches 200 to 300
volts, depending on the design and size of the coil. Such a voltage is
sufficient to break down for an instant the resistance of the air gap when
the circuit is broken, thus permitting the induced current to flow across
the gap and create a very hot, yellow, flashy spark.
-4T ^ 3 -2 3 ■Jt/v«i«*
jndll of Iron >#iRt/V//'i
i jl O <Pundlc of Iron >&\Rt&//J
Battery
Fiq. 173. — Principle of the low-tension coil.
The action of a hick coil may be compared to some extent to the water
hammer in a water pipe. If the valve is closed suddenly when the water
is flowing, the momentum of the water in motion will produce a terrific
blow on the valve, known as water hammer. The instantaneous pres-
sure produced by the water hammer may be several times that of the
ordinary pressure of the water which set up the motion when the valve
was open.
138. The Induction Coil. — When the current for automobile ignition
is derived from either the dry battery, storage battery, low-tension magneto,
or generator, the voltage, which usually ranges from 6 to 12 volts, is too
low to jump the gap between the spark plug points inside of the engine
cylinder. Consequently, the low voltage current must be transformed
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BATTERY IGNITION SYSTEMS
149
to a current of high voltage by a special transformer known as an in-
duction coil. Induction coils may be of either the vibrating or non-
vibrating type, but in either case the general construction and principle
of operation are the same. The chief difference is that the vibrating type
coil operates with a timer and gives a shower of sparks at the plug, while
the non-vibrating type operates with a breaker and gives a single spark
at the plug. The non-vibrating coil is the most popular for automobile
.ignition. Its application to a jump-spark ignition system is illustrated
in Fig. 174.
The induction coil consists essentially of a primary and a secondary
winding both wound on the same core of soft iron wire. This core is
' usually about J^ in. to % in. in diameter and 5 to 6 in. long. The wires
3f*RKPLU6
GROUND
ORCUT THROUGH CN6INC FRAME
Fig. 174. — Jump-spark ignition with breaker and non-vibrating coil.
in the core are annealed to make them as soft as possible so that the core
will magnetize and demagnetize rapidly.
The primary winding which is connected to the source of current
supply consists usually of several layers of insulated copper wire, ranging
in size from No. 16 to No. 20 B. & S. gauge. The wire is wound around
the core so as to make it an electromagnet. The insulation on the wire
usually consists of layers of cotton fiber, though in some cases an enamel
insulation is used.
The secondary or high-tension winding, to which the spark plug is
connected, is wound outside of the primary coil and is made up of several
thousand turns of enameled or silk covered copper wire, usually about
No. 36 B. & S. gauge. This winding is sometimes made up of many
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150 THE GASOLINE AUTOMOBILE
layers each running the entire length of the coil, the layers being insulated
from each other by paraffin wax paper. Another type of construction
is where the winding is made up of several narroV spools or "pancakes"
assembled over the primary coil with suitable insulation between. The
adjacent ends of these pancake coils are connected so that their windings
are in series. To safeguard against the winding becoming short circuited
through moisture, the entire coil is usually imbedded in paraffin, or some
other insulating and moisture-proof compound.
Figure 174 shows a circuit diagram of a simple ignition system for a
single cylinder four-cycle engine. The induction coil is of the" non-
vibrating type operating with a breaker for making and breaking the pri-
mary current. It will be noticed that a condenser is connected across
the breaker contact points. This is to protect the points against pitting
and to assist the primary coil in inducing a high voltage in the secondary
winding. (The operation of the condenser will be taken up later.) The
breaker points are normally held closed by spring tension and open only
when the lobe of the cam lifts the movable contact arm. This cam is
driven by the engine and rotates, at one-half crankshaft speed in order to
produce one spark in two revolutions of the crankshaft. The cam must
be timed with the engine so that the spark will occur when the piston is
nearing the end of its compression stroke.
When the switch is turned on and the cam is in such a position that
the breaker contacts are closed, current flows through the primary circuity
from the positive (+) terminal of the dry cells, through the switch and
primary winding of the coil (magnetizing the core as indicated) to the
insulated terminal of the breaker. It crosses the breaker contacts and"
passes through the contact arm to the ground, returning through the
ground to the negative (— ) grounded terminal of the dry cells, thus com-
pleting the circuit. (A ground circuit is that, part of the circuit in which
current travels through the engine and chassis frame, the frame or ground
acting as a conductor the same as one wire.) When the primary current
is interrupted by the cam lobe lifting the breaker contact arm and sepa-
rating the contact points, the core demagnetizes causing the magnetic
lines of force to collapse cutting each turn of the primary and secondary
wtnding. This sudden collapse of the magnetic lines induces a current
in both windings, causing it to flow around the core in the same direction
.as the original battery current. By having several thousand turns of
very fine wire in the secondary winding, sufficiently high voltage will be
induced in the secondary circuit to force a current to jump across the
spark-plug points, thus completing the circuit and giving the desired igni-
tion spark within the cylinder. The path followed by the secondary
current, as shown by the arrows, leads from one end of the secondary
winding to the spark plug terminal, through the insulated electrode of the
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BATTERY IGNITION SYSTEMS 151
plug, jumping the gap between the plug points to the engine frame and
returning through the engine frame to the other end of the secondary
winding. It will be seen that the primary winding and its current are
used for magnetizing the core. The current which is induced in the
secondary coil when the primary circuit is broken is that used for the
ignition spark.
A voltage will be induced in the secondary winding while the core is
being magnetized as well as when it is being demagnetized, but, owing to
the fact that the core magnetizes much slower than it demagnetizes, the
induced voltage at this time is negligible. When the primary circuit is
broken, the core, assisted by condenser action, demagnetizes very rapidly
and induces a current of very high voltage in the secondary winding. The
voltage thus produced is usually from 10,000 to 20,000 volts.
139. The Safety Gap, — A gap of j^e to % in., known as a safety gap,
is usually provided across the ends of the secondary winding of most
coils such as shown in Fig. 174. Its purpose is to provide a by-pass for
the high voltage current in case a spark plug lead should become discon-
nected and the secondary circuit opened, or in case the spark plug points
should become too far apart for the spark to jump. In case a break
should occur in the secondary circuit, which offers more resistance to the
high-tension current than the resistance across the safety gap, the spark
will jump the safety gap, thereby safeguarding the coil against any ex-
rasive voltage which might puncture the insulation and cause short
circuits.
140. The Condenser. — The action of the primary circuit is similar
to that of the kick coil in a make-and-break ignition system and the
same kind of a flashy spark which occurred between the igniter points
will also occur at the interrupter points when the primary circuit is broken.
In the jump-spark ignition system this spark is prevented and the action
of the coil greatly improved by the use of a condenser. The condenser
consists of two folded strips of tin foil insulated from each other by other
stripe of paraffined paper, each strip of tin foil being provided with a
terminal. The two condenser terminals are connected to the interrupter
terminals as shown in the circuit diagrams of Figs. 174 and 175. The con-
denser may be mounted either in the breaker head or in the coil housing.
There is no electric circuit through a good condenser. If any current does
pass through, the condenser is short circuited and must be replaced.
The condenser has the property of being able to absorb and discharge
an electrical charge, and it is this characteristic which makes its use
essential to jump-spark ignition.
Referring to Fig. 175, the operation of the condenser is as follows:
When the break of the primary circuit occurs, the induced surge of cur-
rent in the primary, which is in the same direction as the original battery
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152
THE GASOLINE AUTOMOBILE
current and which would otherwise cause an arcing of the contact points,
rushes into the condenser and charges it. The side of the condenser which
Induction Coil
:conoa*y
WiNOiNa
Battery
Primary Winding
Condenser
Fig. 175. — Operation of the condenser.
Contact Rwnts
Melo Normally CloslcA
Jhrolkjh Spring Tcns»on/
receives the surge is temporarily charged positive and the other side nega-
tive. Instantly, the condenser discharges back through the primary
winding and battery in the
opposite direction in an at-
tempt to equalize the poten-
tial of the two sides. As
this backward surge is oppo-
site in direction to the origi-
nal magnetizing current, it
assists in quickly reducing
the magnetism of the core to
zero, thus aiding in securing
the maximum voltage in the
secondary winding. In
reality, the current surges or
oscillates to and fro from the
condenser before it finally
dies out. The initial con-
denser discharge is repre-
sented by the crooked arrows.
The action of the condenser may be compared to that of the flexible
diaphragm shown in Fig. 176. When the valve is closed, suddenly
Pi Ft Coil
Flcxisle Diaphragm
Fia. 176. — Water analogy explaining action of
condenser.
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BATTERY IGNITION SYSTEMS
153
cutting off the flow of water from B through the coil of pipe into A, the
water will depress the diaphragm for an instant due to the momentum
attained by the water. The diaphragm will then rebound immediately
forcing a surge of water back through the pipe into B; in fact, the water
will surge back and forth several times before it finally comes to a stand-
still. This surging action of the water is similar to the surging of the
electric current of the condenser.
141. The Vibrating Induction Coil. — The vibrating coil ignition
system differs from the non-vibrating type chiefly in the addition of a
CONDENSER
SPARK PLUG
A
-TIMER
GROUND THROUGH E.NGINE AND CAP FRAME
Fig. 177. — Jump-spark ignition system with vibrating coil and timer.
vibrator to the coil and the employment of a timer instead of a breaker
for opening and closing the primary circuit. The essential parts of the
coil are; a core of soft iron wire, a primary winding of coarse insulated
copper wire, a secondary winding of fine insulated copper wire, a condenser ,
and a vibrator.
In Fig. 177 is shown a circuit diagram of a simple jump-spark ignition
system with a vibrating coil. There are two separate and distinct elec-
trical circuits, namely, the primary and secondary circuits the same as
in the non-vibrating system. The primary or battery circuit includes
the battery, the switch, the vibrator, the primary winding of the coil, the
timer, and the condenser. The condenser is connected across the
vibrator points. The secondary circuit contains the fine or secondary
winding of the coil and the spark plug. When the primary circuit is
completed at the timer (which is usually driven by the camshaft of the
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154
THE GASOLINE AUTOMOBILE
engine), current will flow from the battery through the primary winding
of the coil in the direction indicated by the arrows. The core of the coil
thus becomes magnetized and as long as the current flows this core will
have the properties of a magnet. The core exerts a pull on the iron disc
or armcUure attached to the end of the vibrator and in so doing separates
the contact point on the vibrator from the stationary contact. This
breaks the primary circuit and the current ceases to flow. The core,
therefore, loses its magnetism and the vibrator returns to its former
position. In so doing, it reestablishes the primary circuit and the
action is repeated. Thus, as long as the primary circuit is closed by the
roller making contact with the segment of the timer, the vibrator will
vibrate rapidly similar to the vibrator of an ordinary electric doorbell.
Each time the vibrator opens, breaking the primary circuit, the
magnetic field dies away very quickly followed by a high-tension spark
at the plug. The flashy spark
VIBRATOR POINTS
CONTACT SPRING \
VIBRATOR
ADJUSTING
PRIMARY
-WINDING
which would naturally occur
at the vibrator points is
wiped out by the condenser
which is connected across the
points. Since the vibrator
makes and breaks many
times on each contact of the
timer, a shower of sparks is
delivered at the plug. These
sparks begin at the instant
the contact is made and last
throughout the period of
timer contact.
142. The Three Terminal
Coil. — Many of the coils used
on automobile ignition sys-
tems have only three termi-
nals instead of four. Figure 178 shows a typical three terminal coil such
as is used on the Ford car. One end of the secondary winding is joined
to one end of the primary, and the junction connected to one of the ter-
minal binding posts which in turn leads to the ground through the pri-
mary wiring. The other end of the secondary leads out of the coil to
the spark plug.
143. The Vibrating Type Ignition System.— Where vibrating coils are
used for ignition on a multiple cylinder engine, it is customary to use
a coil for each cylinder. These coils are usually enclosed in an upright
box as shown in Fig. 179, which is a coil-set for a four-cylinder engine.
The box is fitted with interchangeable slip-type coil units such as shown
Fig. 178.
\ PRIMARY TERMINAL CONTACT
— Ford (K-W) induction coil, showing
typical three terminal coil.
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BATTERY IGNITION SYSTEMS
155
in Kg. 178. The connections for these coils are made by contact springs
in the coil box bearing on the metal
contacts of the coil as shown in Fig.
180. This makes it possible to re-
move any of the coils without discon-
necting any of the wiring. The
switch on the front of the box per-
mits the primary current to be used
from either a battery or low-tension
magneto. This system may also be
used with two independent batteries,
one being held in reserve.
Figure 180 shows the circuit dia-
gram of a vibrating coil ignition sys-
tem for a four-cylinder engine using
either dry batteries or low-tension
magneto as the source of current
supply. This is similar to the Ford
system of ignition which will be taken up in the next chapter.
Fio. 179. — Pfanstiehl four-cylinder
coil-set.
COWCMSER
(ONE SIDE OF MAGNETO
W1N0ING 0R0UND)
Fio. 180. — Diagram of four-cylinder vibrating coil ignition system.
144, Timers. — The timer may be defined as a revolving switch for
the purpose of connecting the source of primary current supply to the
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156
THE GASOLINE AUTOMOBILE
proper coil at the proper time. It is, consequently, always placed in the
primary circuit. The timer used on the Ford engine is shown in Fig. 181.
The inside or rotating part is fastened to, and rotates with, the camshaft.
When the roller comes into contact with one of the four terminals on the
housing, the primary circuit is completed through the coil connected to
Pull Rod Connection
Case
Thumb Nut
Contact Poim
Roller Ann
Brush
Engine Cover
Fio. 181.— The Ford timer.
that terminal, causing its vibrator to operate and a series of sparks to
occur in rapid succession at the plug. The housing of the timer does not
turn with the camshaft, but can be shifted forward or backward in
respect to the camshaft and roller either to advance or retard the time
of the spark.
Binding posts
l CLtCTfiOOtS
Comical Type
INSULATOR
WLLD IN PLACC
•v SV»HIN«
Bosch Pi.ua
SHOWINS INSULATOR
SEALED IN POSITION
Fio. 182. — Construction of typical spark plugs.
- The timers for six- and eight-cylinder engines are similar to the above
but have six or eight insulated terminals instead of four equally spaced
in the housing.
s 145. Spark Plugs. — The spark plug consists of two terminals fastened
together, but insulated from each other, and the whole screwed into the
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BATTERY IGNITION SYSTEMS
157
cylinder. Figure 182 illustrates the internal construction of typical
plugs. The center terminal is insulated from the rest of the plug and the
other terminal. The insulation between the center electrode and the
Fiq. 183.— Types of spark plugs.
body of a plug is usually either of porcelain or of mica. The outside
terminal is in contact with the engine cylinder and is, consequently,
grounded. The only way the current can get from one terminal to ffie
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158
THE GASOLINE AUTOMOBILE
other is across the air gap between them. The gap between points for
battery ignition systems on the average automobile engine of normal
compression up to 80 lb. should be about J^2 in., or the thickness of
a smooth dime. On engines of higher compression the points should be
set a trifle closer to compensate for the increase in resistance across the
plug points caused by the high compression.
Figure 183 shows a few of the many types of spark plugs now in use.
Although the designs vary a great deal to suit different conditions the
purpose of each is the same, namely, to ignite the charge within the
cylinder. One of the important factors in the operation of a spark plug
is its proper installation in the cylinder or cylinder head. Figure 184
shows proper and improper methods of installing spark plugs.
Corrcct Incorrect
Fio. 184. — Correct and incorrect methods of installing spark plugs.
146. Spark Plug Testing. — The porcelain of a spark plug may become
cracked due to the intense heat or to accident. The plug is then usually
short circuited and no spark is produced in the cylinder. A broken por-
celain can sometimes be detected by a grating sound when an effort is
made with the fingers to wiggle the porcelain of the plug before it is re-
moved from the cylinder. The plug may also become short circuited
through carbon or oil deposits between the plug points.
The spark plug which seems to spark properly when tried out on a
cylinder block may fail entirely inside the cylinder because of the greater
resistance the spark encounters under the compression pressure. Con-
sequently, the most satisfactory way to test a plug is to test it under
operating conditions. To determine which cylinder is missing fire, the
plugs may be short circuited one or more at a time, with the engine run-
ning, by holding a screwdriver or hammer head from the plug terminal
to th^ engine frame, or the wires may be detached from the spark plug,
one 6r more at a time, and the change in engine power noted. If the
plug ha§ not been operating there will be no change in engine power,
but if the engine shows a material loss of power, it indicates that the plug
has been operating satisfactorily. Also, the priming cups may be opened
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BATTERY IGNITION SYSTEMS 159
one at a time and the issuing flame watched. A hot flame should issue
with each explosion of the cylinder.
A sooty, oily appearance of the spark plug points when removed from
the cylinder also indicates that the plug has not been working properly.
A white or yellowish white clean dry appearance of the porcelain indi-
cates that the cylinder has been firing. Probably the most satisfactory
method of testing a spark plug is to exchange plugs between the cylinders
or to try out a plug which is known to be good in the cylinder which is
misfiring.
If the plug is not to be taken apart it can be cleaned with a brush
and gasoline. If it is taken apart the porcelain may be cleaned without
scratching it by using water and a little road dust. If emery cloth were
used, the porcelain would be scratched. Figure 185 shows the Champion
spark plug cleaner which screws onto the plug. The container is filled
with gasoline and upon being shaken, the needles in combination with
the gasoline remove any carbon deposit that may be on the plug. y
mCUm^r fluforf Pick wy GAtm
Fig. 185. — Champion spark-plug cleaner.
It is important that all the plugs in the engine be set with the same
gap. If the gap is over 3^2 hi- or -030 in., the cylinders are liable to
misfire on a hard pull. If the gap is set much closer than .020 in., the
cylinders will probably miss when the engine is running idle.
147. Typical Battery Ignition System. — The main parts of a modern
automobile battery ignition system are: the storage battery, high-tension
non-vibrating coil, breaker, and distributor. The battery is the source of
the electric current. The breaker and distributor are usually combined in
one unit driven by the same shaft from the engine. Figure 186 shows a
circuit diagram of a typical battery ignition system for a four-cylinder
engine. The distributor unit contains the breaker points which make
and break the primary current, and also the distributor which directs
the high-tension current to the individual cylinders in their proper firing
order. The breaker points are two small contact pieces, usually tungsteij
or platinum, one stationary and the other one on a movable arm. The
points are normally held closed by spring tension. A small cam with as
many lobes as there are cylinders, revolves and separates the two points
about ^4 in., interrupting the current in the primary winding of the coil
every time a spark is required at one of the plugs. The points are made
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160
THE GASOLINE AUTOMOBILE
of tungsten alloy or platinum to withstand pitting due to the sparking
between them as the points separate. To prevent this sparking a con-
denser connected across the two contacts is used to absorb the surplus
current that would have a tendency to keep on flowing after the circuit
is broken.
148. The Distributor. — The distributing arm for the high-tension
current is in the head of the distributor and connects the center terminal,
or high-tension lead from the coil, with the contacts leading to the indi-
vidual spark plugs, there being as many contacts as there are cylinders.
The bodies of the distributor head and arm are molded of a very high re-
sistant insulating material known as bakelite and designed to be as water
and dust proof as possible.
taMTMft
GaouNDTnnoutM enow* mo cm* frami
Fio. 186. — Diagram of typical battery ignition system.
149. The Ignition Resistance Unit — The ignition resistance unit
which is found on many storage battery ignition systems and which is
shown in Fig. 186 is for the purpose of protecting the coil winding from
overheating and the battery from excessive discharge in case the switch
is left on with the engine not running and breaker points closed. It also
assists in equalizing the intensity of the secondary spark at high and low
engine speeds. It consists usually of a number of turns of special iron
resistance wire, similar to that in an electric toaster. The resistance of
this unit is considerably more than that of the primary winding of the
ignition coil.
If the switch is left on, the resistance of the iron wire increases gradu-
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BATTERY IGNITION SYSTEMS 161
ally with increase in temperature, due to the primary current, until the
wire begins to turn to a cherry red when the resistance takes a sudden rise.
This causes the current discharge from the battery through the primary
winding to decrease, thus protecting the coil against possible damage
from overheating, and the battery against rapid discharge. It will also
be found that at low engine speed the temperature of the resistance wire
will be lower than at high speed, partly due to the longer period during
which the contacts are closed, and partly to the impedance or opposition
exerted by the coil against being magnetized rapidly. This opposition
will increase more and more with increase in engine speed. The period of
time which the primary current has for magnetizing the core will decrease
in proportion to the increase in engine speeds. The breaker will then have
the tendency to interrupt the primary current before the core is fully
magnetized, thus decreasing the intensity of the secondary spark. . This
is counteracted by the decrease in resistance of the resistance unit which
permits a large momentary flow of current through the primary winding
when the breaker points are closed. By controlling the primary current,
the intensity of the secondary voltage is thus equalized at high and low
engine speeds.
160. Spark Advance and Retard. — On a variable speed gasoline engine
it is very essential that the time at which the spark occurs in the cylinder
be changed according to the engine speed, since it takes a certain length
of time for the explosion to take place regardless of the engine speed.
When the engine speed is high, the spark must occur before the piston
reaches dead center in order to have the full force of the explosion exerted
when the piston has just passed the center position. When the engine
speed is slow, the spark can occur later and the force of the explosion will
be exerted just after dead center. It is necessary when starting the
engine that the spark occur when a piston is approximately on dead center.
When the engine must start on ignition from a high-tension magneto,
the spark can occur slightly before dead center. This is especially
true when an electric starter is used, on account of the high cranking
speed.
These various considerations demand that the position of the spark
be made variable. This is usually done by shifting the timer, or inter-
rupter housing, causing the break of the primary current (and, conse-
quently, the spark in the cylinder) to occur earlier or later. The position
of the spark in most cases is governed by the spark control lever on the
steering wheel. In starting the engine, the spark should be retarded so
that it will not occur until the piston is starting on its downward stroke.
The spark should then be advanced as the engine increases its speed. If
the spark is too far advanced, there will be a decided knock in the
cylinders.
10
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THE GASOLINE AUTOMOBILE
161. Automatic Spark Advance. — In several modern ignition systems,
means are provided by which the position of the spark is advanced and
retarded automatically with the changes in engine speed. The purpose
of this is to relieve the driver of the responsibility and uncertainty of
correctly gauging the proper position for setting the spark control lever
during normal driving speeds. Figure 187 shows the Delco ignition
breaker and automatic spark advance mechanism as used on the Hudson
Super-Six.
As can be seen from the figure the automatic advance mechanism is in
the form of a revolving weight type governor mounted on the timer shaft
below the interrupter cam. The weights are carried by a ring which is
mounted on a short hollow shaft integral with the cam. Above the cam
is mounted the distributor arm or rotor which rotates with it. The
entire mechanism is arranged so that, as the engine speeds up and the
AQJUSTINQ NUT
CONTACT POINTS
LOCK I NO
SCREW
DISTRIBUTOR
"COMTACT BUTTOM
■ *-■ DISTRIBUTOR ROTOR
MOUNTED ON CAM
CAM TIMING
AOJUSTHCHF
SCREW
PRIMARY
TERMINAL
CONDENSER
AUTOMATIC AO VANCE
RING
MANUAL ADVANCE
LEVER
RESISTANCE
UNIT
View of Breaker Mechanism
with Distributor Rotor Removed
Vie.w showing Automatic
Spark Advance Mechanism
Fio. 187. — Delco battery ignition unit on Hudson Super-Six showing breaker and auto-
matic spark advance mechanism.
weights spread outward against the resistance of the spring, the ring and
cam are shifted in a forward direction in respect to the timer shaft. This
has the effect of advancing the spark automatically to the correct position
in proportion to the engine speed. As the engine speed decreases, the
springs pull the weights inward and the spark is automatically retarded.
The manual spark advance lever is connected to the spark control
lever on the steering wheel and is for the purpose of securing proper timing
and hand control of the spark under various conditions, such as starting,
difference in gasoline, variable weather conditions, and at extremely high
speeds requiring spark advance beyond the automatic advance range.
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BATTERY IGNITION SYSTEMS
163
Other types of automatic spark advance mechanism will be discussed in
connection with the system on which it is used.
162. The Atwater-Kent Ignition System — Open Circuit Type. — The
Atwater-Kent battery ignition systems include two principal types, the
open circuit type in which the interrupter points are normally open, and
the closed circuit type in which the interrupter points are normally
closed.
A typical example of the open circuited type Atwater-Kent system
which has been widely used is known as type lf-2, the unisparker of which
is shown in Fig. 188. The principal parts of the system consist of:
1. The unisparker, which combines the special form of contact maker,
which is the chief feature of this system, with a high-tension distributor.
2. The coil} which consists of a simple
primary and secondary winding, with con-
denser— all imbedded in a special insulating
compound. The coil has no vibrators or
other moving parts, this function being per-
formed by the contact maker.
3. The ignition switch, which reverses the
direction of the primary current across the
interrupter points each time the switch is
turned on. This is called a polarity chang-
ing type switch.
The unisparker is connected to the ordi-
nary timer shaft of the engine. The dome-
shaped cover contains the primary contact
maker and the secondary distributor, as well
as the spark advance mechanism. Figure 189
shows an exploded view of this construction.
An important feature of the contact maker is
that the length of contact is absolutely independent of the engine
speed, and as strong a spark is produced when the engine is cranked as
when it runs at normal or even at racing speed. The length of con-
tact is constant and not greater at any speed than is necessary to insure
the magnetic field of the coil being built up to its full strength.
The action of the contact mechanism is shown in Fig. 190. The four
views show the movement described in producing one spark. The prin-
cipal moving parts are: the hardened steel rotating shaft in the center
with as many notches as there are cylinders, the lifter, the latch, and the
contact spring. The contact points are normally open. The contact
is made and broken by the action of the lifter spring in drawing the lifter
back; or after it has become unhooked from the notched shaft. When
the lifter is pulled forward by the notched shaft it does not touch the
I
Fio. 188.— Atwater-Kent Uni-
sparker, Type K-2.
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THE GASOLINE AUTOMOBILE
latch. It is pulled forward until it reaches a point where it unhooks
from the notched shaft and is then pulled back by the lifter spring, strik-
ing the latch as it returns. The latch being struck by the lifter, presses
against the contact spring and closes the points for a brief instant opening
DISTRimnOR
TERMINAL.
RUBBER
WASHER
CLAMP SCREW
CONTACT SCREW
HOLDER
INSULATED
CONTACT SCREW
SPRING CONTACT ARM -
LIFTER
BASE PLATESCREW-
UFTER GUIDE SCREW
CONTACT ARM HOLDER
MAIN BODY CASTING
GOVERNOR WEIGHTS-
GOVERNOR SPRING5-
y- DISTRIBUTOR
*&M BLOCn
DISTRIBUTOR CLAMP
BINDING POST SCREW
BINDING POST WASHER
BASE PLATE
— LIFTER SPRING
-NOTCHED SHAFT
Pio. 189. — Construction of Atwater-Kent ignition unit. Type K-2.
immediately after the lifter passes. With the latch and lifter having
returned to their original position the mechanism is again ready to repeat
the same operation for producing the next spark. The spring action
(B)1^ (CX^WM (Of
••HTM
■R«ni
Fio. 190. — Operation of Atwater-Kent contact mechanism for Type K-2 ignition system.
makes the speed of the break independent of the speed of the engine.
It also makes the time of contact uniform, and since the period of contact
is so brief, the system draws the least possible current from the batteries.
This makes it particularly adapted for use with dry cells.
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BATTERY IGNITION SYSTEMS
165
la Fig. 191 a complete wiring diagram of the Atwater-Kent system,
Type K-2, is shown. The switch is of the polarity changing type which
reverses the direction of current across the interrupter points each time
the switch is turned on. The switch has two positions off and on.
One time when the switch is on, terminal B is connected to S, and
B' to S'. The next time it is turned on, by turning the switch another
quarter turn in the same direction, the connection is reversed, connecting
B to S', and B' to S. This reverses the direction of the primary current
through the unisparker. The purpose of this is to equalize the transfer
of metal produced by the action of the spark at the point of contact,
thereby decreasing the wear and increasing the life of the points.
contact,
saw—
IGNITION SWITCH
(POLARITY CHANGING TYPE)
IGNITION SWITCH
(REAR VIEW)
UNISPARKER
Fio. 191. — Wiring diagram for Atwater-Kent ignition system, Type K-2.
Contact Point Adjustment. — The normal gap between the contact
points is from .010 in. to .012 in. — never closer. When the gap be-
comes too wide, due to wear, the engine will be hard to start and will
fire irregularly. The head of the contact screw, Fig. 191, is set up against
several thin washers. A sufficient number of these washers should be
removed to give the correct gap when the screw is set up tightly.
The contact points are made of purest tungsten, which is many times
harder than platinum.
When contact points are working properly, small particles of tungsten
are carried from one point to the other, sometimes forming a rough sur-
face, characterized by a dark grey color. The rough surface does not
in any way affect the proper working of the points, owing to the fact
that the rough surfaces fit into each other perfectly. However, when it
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THE GASOLINE AUTOMOBILE
becomes necessary to take up the distance between these points, due to
natural wear, it is advisable to remove both contact screw and spring
contact arm, and dress down the high spots with a new fine file. This
makes it possible to obtain a more accurate adjustment and eliminates
any danger of any high points on the two contacts touching when the
system is at rest.
Automatic Spark Advance. — Figure 192 shows the centrifugal governor
which advances the spark as the speed increases. The rotating shaft is
divided, and as the governor weights expand they rotate the upper part
of the shaft forward in its own direction of rotation, thus making and
breaking contact earlier than at slow speed.
Timing the Spark. — Since the type, K-2, is not generally used with
a spark control lever it should be installed so as to allow a small amount
Motor stopped or running slowly. Motor at high speed.
Fia. 102. — Atwater-Kent automatic spark advance mechanism.
of angular movement for the initial timing adjustment. In other words,
the socket into which the unisparker fits should be provided with a clamp
which will permit the unisparker to be turned and locked rigidly in any
given position.
In timing, the piston in No. 1 cylinder should be raised to upper dead
center, between compression and power strokes. The clamp which holds
the unisparker should be loosened and the unisparker should be slowly
and carefully turned backward or counterclockwise (opposite in direc-
tion to the rotation of the timer shaft) until a click is heard. This click
occurs at the exact instant of the spark. At this point, the unisparker
should be clamped and care taken not to change its position. The dis-
tributor head which fits only in the one position should now be removed
and the position of the distributor block on the end of the shaft noted.
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BATTERY IGNITION SYSTEMS
167
The terminal to which it points should be connected to No. 1 cylinder.
The other cylinders in their proper order of firing are then connected to
the other terminals in turn. When these connections are made, the
direction of rotation of the timer shaft must
be kept in mind.
When timed in this manner, the spark oc-
curs exactly on center when the engine is <
turned over slowly. At cranking speeds, the
governor automatically retards the spark for
safe starting, and, as the speed increases, the
spark is automatically advanced, thus re-
quiring no attention on the part of the driver. '
Among the particular features of this Fio. iya.— Atwater-Kent fgni-
system are: timg of closed primary circuit is tion unit» Tyv* cc*
independent of engine speed; speed of break
is independent of engine speed; circuit cannot be closed when engine is
stopped; battery consumption is reduced to a minimum; the spark is
uniform in all cylinders and is independent of engine speed.
Pro. 194. — Atwater-Kent system mounted on Maxwell engine.
163. The Atwater-Kent Ignition System, Type CC. — This system dif-
fers from other Atwater-Kent models in that it operates on the closed
circuit principle. It was developed for use on cars equipped with a start-
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168
THE GASOLINE AUTOMOBILE
ing and lighting system and is intended to operate on current from a stor-
age battery. It consists of a breaker and distributor unit mounted with
a non-vibrating coil on a base as shown in Fig. 193. This unit has the
same general dimensions as the standard high-tension magneto and is
driven in the same manner. For this reason it is termed a magneto
replacement unit. Figure 194 shows this Atwater-Kent installation on
the Maxwell engine.
The principal feature of the system lies in the design of the breaker
mechanism which is shown in Fig. 195. The contact maker consists of
an exceedingly light steel contact arm, the end of which rests lightly on
a hardened steel cam which rotates one-half as fast as the engine crank-
shaft. For use on four-cylinder engines, the cam has four lobes which
open the contact points four times for each revolution of the timer shaft
or twice for each revolution of the engine crankshaft. Each time the
contact points are opened, the primary circuit of the ignition system is
Fia. 195. — Atwater-Kent breaker
mechanism, Type CC.
Fia. 106. — Construction of Atwater-
Kent distributor head, Type CC,
interrupted, thus producing a discharge of secondary high-tension cur-
rent at one of the spark plugs. The normal gap between the breaker
points should not be less than .005 in. nor more than .008 in. The
standard setting is .006 in. This is about the thickness of two pages
of this book.
The distributor head, a section of which is shown in Fig. 196, forms
the top of the contact maker. Each spark plug wire terminates in an
electrode which passes through the distributor cap and a rotating distribur
tor block which takes the high-tension current from the center terminal
of the distributor and distributes it to the plugs in the proper firing order.
The distributor block just clears the distributor points without actually
touching. The high-tension current jumps this small gap without appre-
ciable loss. The secondary spark occurs when the contacts separate.
Another feature is that the condenser is mounted directly on the
contact maker instead of in the coil. This greatly simplifies the entire
ignition system and increases the life of the contacts.
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BATTERY IGNITION SYSTEMS
169
In Fig. 197 is shown a complete circuit diagram of the usual type
CC installation. In some cases the ignition switch may be combined with
SPARK
IGNITION SWITCH
I
i
BATTERY^
GROUND
— DISTRIBUTOR
BREAKER
INDUCTION COIL '
Fio. 197.r— Wiring diagram of Atwater-Kent ignition system, Type CC.
the lighting switch. With the type of switch shown, the primary circuit
is complete when the ignition button is
pushed in, the arrows indicating the path
of the current. A resistance unit is
mounted in the top of the coil to provide
protection to the coil and battery in
case the switch is left on. It also assists
in equalizing the secondary spark at high
and low engine speeds, as previously ex-
plained.
154. The Connecticut Battery Igni-
tion System.— The principal parts of this
system consist of an igniter , a non-vibrat-
ing induction coil, and a switch as shown
in Figs. 198, 199, and 200.
The igniter, details of which are shown
in Figs. 201 and 202, operates on the
closed circuit principle, the primary cir-
cuit being interrupted or broken, and the
secondary spark produced when the lobes
of the cam strike the roller of the contact arm. The cam has as many
Fio. 198. — Connecticut igniter,
Model 16C.
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170
THE GASOLINE AUTOMOBILE
lobes as there are cylinders and rotates at one-half crankshaft speed.
The distributor arm, which directs the secondary current to the various
plugs in their proper order of firing, is carried above the cam on the
upper end of the same shaft. In most installations, the igniter is
BRASS GROUNDING
STRIP
' l^^^P^^/ » ^1
^SAFETY
\ GAP
S^ .^r'^^^L^
^ 1)
v^*^ tr2
5/
FiQ. 199. — Connecticut coil showing spark gap and connections.
mounted on the side of the engine and is driven through spiral gears
from one end of the generator shaft.
The coil which also houses the condenser is mounted close to the
igniter on the engine frame, or on top of the generator, and is connected
Fig. 200. — Front and rear views Connecticut combination lighting and ignition
switch. Type H-MD.
to the breaker by short flexible leads. One side of the condenser, as
well as one side of the primary and secondary winding, is grounded
through the brass strip on the side of the coil to the coil base and engine
frame. The condenser, although mounted in the coil, is connected across
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BATTERY IGNITION SYSTEMS
171
the interrupter points through the two short leads which connect the coil
with the igniter. Its purpose is to protect the points against pitting,
as previously explained.
Fxo. 201. — Connecticut igniter with distributor head removed showing breaker
mechanism, Models 16 and 16C.
Fig. 202. — Connecticut igniter with distributor head removed showing breaker mechanism
model.
A complete- circuit diagram of the Connecticut system is shown in
Fig. 203. The automatic switch of this system, as shown in Figs. 203
and 204, is a feature unique in ignition apparatus and is used only on
Connecticut systems. Its function is to open the switch, should the
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172
THE GASOLINE AUTOMOBILE
primary circuit be closed an unusual length of time, as in the case of
a car being left with the switch on and the engine stopped. This will
prevent the draining of batteries and overheating of the coil. When the
T© SMRK PLUOS
LMNTNW SWITCH IGNITION SWITCH
KEY OFF ON
g g jg g ^
BREAKER
tne*no*TAT
*i°*TAT £6391
DETAIL OF
THtRMOSlWf
BATTERY
Fio. 203. — Wiring diagram of Connecticut battery ignition system.
ignition button (the left-hand button to the driver) is pushed in, the
primary current from the battery completes its circuit as indicated.
From the positive battery terminal, the current flows to the switch
Fio. 204. — Internal view of Connecticut automatic ignition switch.
terminal B, then through the switch contacts and resistance element
to switch terminal C, which is connected to terminal C on ooil. The
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BATTERY IGNITION SYSTEMS 173
current now flows through the primary winding of the coil to the station-
ary side of the igniter, across the breaker points to the grounded terminal
of the coil, returning to the negative terminal of the battery through the
ground. The current induced in the secondary winding of the coil flows
from the secondary winding to the center of the distributor, through the
distributor arm to the spark plug, across the plug, and back to the
grounded coil terminal. The ignition is turned off by simply pushing in
the off button. It will be noted that a spark gap is provided to protect
the secondary winding from the destructive action of the high voltage,
in case a plug terminal should become disconnected, so that the high-
tension current cannot take its regular path. The safety gap is in a
mica tube inaccessible to vapor o* fumes. It is conveniently arranged
for observation in cases of misfiring cylinders.
A study of Fig. 203 will also show the principles of the automatic
switch mechanism. When the switch is left on and the current flows
continuously through the resistance unit surrounding the thermostat arm,
the resistance unit will heat, causing the thermostat arm to bend suffi-
ciently to close the contacts E. This will complete a circuit from the
battery through the winding of the electromagnet, causing the arm F to
vibrate rapidly. The end of arm F upon striking the lever G, automat-
ically releases the switch button. The thermostat can be adjusted to
operate at any time from 30 seconds to 4 minutes. This adjustment is
made after the engine stops, by varying the gap of the contacts E. The
normal setting is to release in about three-quarters of a minute.
The breaker mechanism is very simple as Figs. 202 and 203 show.
In operation, the rotation of the cam C causes it to touch the fiber roller
R in the arm A, thus separating the contacts. The arm is returned to
its normal position by a spring. The contacts should be adjusted to
open .020 in.
The breaker mechanism is mounted on a plate which rests, in the
casing and is held in place by a spring ring and also by a solid ring, the
latter being held by two screws as shown in Fig. 202. The advance lever
engages a pin on the breaker plate, the whole plate being advanced
around the shaft to advance the time of ignition.
Inasmuch as the system operates on the closed circuit principle,
the maximum time is allowed for the complete magnetization of the
induction coil. The intensity of the sparks produced at the plugs depends
upon this magnetization. It follows that the slower the speed of the
engine the greater will be the magnetization of the core and the greater
the spark intensity. However, this is partly counteracted by the action
of the resistance unit surrounding the thermostat. The resistance unit
tends to equalize the intensity of the secondary spark at high and low
engine speeds in the same way as the resistance units on other systems.
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174
THE GASOLINE AUTOMOBILE
166. The Remy Ignition System. — The Remy battery ignition system
which is of the high-tension distributor type consists principally of
a vertical breaker unit, Fig. 205; a non-vibrating coil, a typical design
of which is shown in Fig. 206; and a switch which may be of either the
BATTERY WIRE
FROfl/bNIPON SWITCH
SECONDARY
WRETUCEN
01 DtS7R.'3U.
WIRE TV INSULATED
BREAKER TERMINAL
COIL BASE GROUNDED
ON ENGINE FRAME
Fio. 205. — Remy battery
ignition breaker and distrib-
utor unit.
Fig. 206. — Remy induction coil — two primary terminal
type.
plain or polarity changing type. The ignition switch is often combined
with the lighting switch.
One type of Remy ignition system which has been used very exten-
sively is that shown in Fig. 207. In this system the breaker is driven
IGNITION BREAKER
AND DISTRIBUTOR UNIT
PBIMARY TERMINALS /
INDUCTION COIL
RESISTANCE UNtT
Fia. 207. — Remy ignition type generator.
from the generator shaft through spiral gears and the coil is mounted
close by on the generator frame. The coil is supported by a special
bracket which also serves to ground one side of both the primary and
secondary windings. The breaker operates on the closed circuit principle
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BATTERY IGNITION SYSTEMS
175
and is very simple in construction as may be seen from Fig. 208. The
interrupter comprises two contact points of platinum-iridium or tungsten,
usually the latter, one being stationary while the other is carried at the
free end of a pivoted lever which bears against the rotating steel cam.
The cam has accurately ground corners (one for each cylinder) which
bear against the fiber block on the lever in rotation and cause the contact
points to open and close at correct intervals. The cam has as many
lobes as there are engine cylinders and is, therefore, driven at one-half,
crankshaft speed. The high-tension current is distributed to the spark
plug leads by a distributor brush which is carried above the cam but does
not touch the pins in the distributor head.
The distributor brush also carries the safety gap which is a gap
of % in. between the distributing segment and the bottom plate which is
grounded upon the shaft. This provides a safety gap across which the
spark can discharge in case any of the connections from the distributor
CONTACT
ARM
BREAKEf?
POINTS
SAFETY
GAP
Fio. 208. — Remy breaker and distributor.
to the spark plugs should become broken. The destruction of the coil
windings due to excessive voltage is thus prevented. The safety
gap should not be less than 1^^2 in- as the spark might then discharge
across it instead of across the spark plug gap, when the plug is under
compression.
Some of the distributor units are equipped with an automatic spark
advance in which the governor mechanism is mounted in the housing
below the cam. The advance of the spark is provided by the revolving
weights which spread more and more due to centrifugal force and shift
the cam in an advance direction. As the engine slows down the cam is
shifted in the reverse direction and the spark is retarded.
Two types of coils are used. One has two primary terminals on top,
as shown in Fig. 206, in which case the coil operates with a simple switch
of the on and off type, while the other has three primary terminals on
top as shown in Fig. 207 and operates with a four-terminal switch of
the polarity changing type. In both cases the condenser is placed in-
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176
THE GASOLINE AUTOMOBILE
side the coil housing and a resistance unit is mounted on top for con-
trolling the primary current. Figure 209 shows a typical wiring diagram
of the Remy system using a two terminal coil, and Fig. 210 shows a
typical wiring diagram of the system using the three terminal coil.
TO SPARK PLUGS
SIMPLE KEY 5WITCH S
— • M
BATTERY
u
>
x
DISTRIBUfOR
BREAKER
Fig. 209. — Wiring diagram for Remy battery ignition system using two primary terminal
coil.
The purpose of the polarity changing type switch is to reverse the
direction of current flow across the breaker points each time the ignition
is used. It is absolutely necessary that the ignition switch be placed
in the off position when the engine is not running. If it is left in the
on position, current from the storage battery will discharge through
TO SPARK PLUGS
IGNITION SWITCH
(POLARITY CMAN«lMa TYPE)
DISTRIBUTOR
Fig. 210. — Wiring diagram for Remy battery ignition system using three primary terminal
coil.
the ignition coil. If this discharge continues, the battery will be ex-
hausted. To aid in preventing theft or unauthorized use, the operator
should remove the switch key when leaving the car.
Adjustment of Contact Points. — Contact points should have a maxi-
mum opening of .020 in. to .025 in. or the thickness of the gauge which
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BATTERY IGNITION SYSTEMS 177
is on the side of the wrench furnished for adjusting the contact point
opening. It is recommended that an inspection of the points be made
every 1000 miles. If the points are found, to be worn unevenly or are
dirty, they may be cleaned by passing a fine flat file, or preferably a
piece of No. 00 sandpaper, between them. When the contacts are
properly fitted they should make clean square contact as shown by A
in Fig. 211. Adjustment of the gap between the contacts is made by
loosening the lock nut with the wrench furnished, turning the adjusting
screw, and then locking the nut again. These contact points should not
be oiled. A slight trace of vaseline placed on the fiber block or on the
cam every 1000 miles will keep the cam from rusting.
Timing Ignition to the Engine. — The proper time of opening the breaker
contact points relative to the travel of the piston is determined as follows:
The distributor advance lever is pushed back to full retard position. The
engine is brought to dead center position with No. 1 piston at the top of
its compression stroke. Dead
center is accurately indicated when Cornet /ncomct
the line U.D.C. on the flywheel is
opposite the corresponding prick A-
punch mark or ind&tor on the
engine frame. I^0K position of
the flywheel, the jfctons in both
of the cylinders indicated by the
numerals after U.D.C. will be at _
-i . »,i w . i -r» i ij. **o. 211. — Correct and incorrect shapes for
the top Of the Stroke. By holding battery breaker contact points.
the finger over the open petcock
as the engine is turned in the proper direction of rotation the cylinder
on compression can be determined. The breaker contact points should
just be starting to separate (the flywheel being turned in the direction
of rotation past dead-center position) for a six-cylinder engine, or from
1 in. to 1% in. (as measured on flywheel) past dead center for a four-
cylinder engine.
If it is found necessary to readjust the timing, the distributor arm
(which has an arrow on it) should be removed and the nut which holds
the cam in place unscrewed. The cam can be loosened by giving it a
sharp rap to release it from the tapered part of the shaft on which it fits
snugly. The cam should then be turned to obtain the proper time of
opening the contact points, noting that the cam strikes the fiber in the
proper direction of rotation. The cam should be rapped down in place
and the nut tightened to keep the cam from slipping.
Oiling. — The grease cup below the distributor head should be kept
full of medium grease, and should be given two turns to the right every
500 miles, so as to force a little grease into the bearing.
12
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178
THE GASOLINE AUTOMOBILE
Spark Plugs. — Failure of spark is sometimes due to the spark plug
gap inside the cylinder becoming clogged with carbon or oil. This
gap should measure .025 in. to .030 in. or the thickness of the gauge
supplied by the manufacturer.
166. The Remy-Liberty Ignition Breaker for U. S. Military Truck.—
The special battery ignition breaker manufactured by the Remy Electric
Company for the U. S. Standardized Military truck Class B is shown in
Figs. 212 and 213. The breaker is of the closed-circuit type and operates
with a plain non-vibrating coil. Both breaker and coil are mounted on
the left side of the engine in front of the water pump. The coil is de-
signed so that a resistance unit is not used in the primary circuit. The
A
-WflARY
\ JMAt
SPARK ADVANCE
LEVER
OILER
Fia. 212. — Remy-Liberty battery ignition unit for U, S. Military truck, Class B.
condenser is mounted inside the distributor head where it is very acces-
sible. Another feature is that the breaker mechanism is mounted on a
plate separate from the main distributor body. This permits the ad-
vancing and retarding of the spark by simply shifting the breaker mechan-
ism around the cam instead of shifting the entire head, thus avoiding
the bending of the wiring. The operation and adjustment of the system
are identical with other systems of the closed-circuit type.
167. The North East Ignition System. — The installation and wiring of
the North East battery ignition system as used on the Dodge car is shown
in Fig. 214. The ignition unit, Fig. 215, is virtually a magneto replace-
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BATTERY IGNITION SYSTEMS
179
ment outfit, being driven the same as a magneto. This unit comprises
an induction coil, a breaker of the closed-circuit type, a condenser mounted
in the breaker housing, and an automatic spark advance mechanism. The
CONDENSER
TIMING ADJUSTING SCREW
CAM
PLATE CARRYING
' BREAKER MECHANISM
BREAKERPOINTS
(ADJ. 70 OPEN '0.0/7.
7V 0.022 OF AN INCH)
TERMINAL CONNECTED
TO COIL
DISTRIBUTOR ARM
'DISTRIBUTOR
Fig. 213. — Construction of Remy-Liberty battery ignition unit for U. S. Military truck,
* Class B.
latter is shown separately in Fig. 216. Either one of two types of breaker
is used. In one type the terminals of the breaker are both insulated and
BATTERY
INDICATOR
IGNITION & LIGHTING
SWITCH
STARTING SWITCH
/ AND CUT-OFF
TO STARTER
GENERATOR
I2-V0LT
BATTERY
'GROUND
IGNITION UNIT
Fio. 214. — Installation and wiring of North East ignition system on Dodge.
the system operates with a polarity changing type switch. In the
other type, Fig. 217, one breaker terminal is grounded and the system
operates with a simple key switch.
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180
THE GASOLINE AUTOMOBILE
The principle of the system as well as the method of ignition timing
is very similar to that in other systems of the closed-circuit type. To
time ignition the cam is loosened and the time of contact break is ad-
justed by shifting the cam so that the points are on the verge of separat-
ing (if the cam were turned forward) with No. 1 piston about J^ in. to
% in. (as measured on the rim of the flywheel) past upper dead-center
position.
TERMINAL CONNECTION
W SWITCH ON
'DASfc^
DISTRIBUTOR
HiGti TENSION'
LEAD FROM
INDUCTION COfL
TO DISTRIBUTOR
HOUSING CONTAINING
AUTOMATIC SPARK
ADVANCE MECHANIST!
Fiq. 215. — North East-ignition unit.
A good way to check the time of contact break is with a test lamp,
connected as shown in Fig. 218. After the ignition switch is turned
on, the engine should be turned over slowly by hand. The light will
flash on and off, depending upon whether the contacts are open or closed.
^GOVERNOR WEIGHTS
.DRIVING SHAFT
GOVERNOR
SPRINGS
SPIRAL GEAR DRIVE
7V TIMER SHAFT
Fiq. 216. — North East automatic spark advance mechanism.
The instant the points separate the lamp will light. The light should
occur (with the above setting) when the dead-center mark on the flywheel
is % in. to Y± in. past dead-center position. The time of contact opening
should be the same for each cylinder. The points should be adjusted
to separate .020 in.
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BATTERY IGNITION SYSTEMS 181
168. The Delco Ignition System. — Many types of Delco ignition
equipment are in use. A few of these are shown in Fig. 219. The
varied designs are due not so much to the principle involved, as this
is practically the same in all models, but to the many individual ignition
requirements of the four-, six-, eight-, or twelve-cylinder engine on which
they are used.
INSULATED
TERMINAL\
£
\
CONDENSER^ . .y^flL
TIME ADJUSTING 4~ - JE&M
NUT ffitt-g
WCAM
5 W
DISTRIBUTOR
HIGH TENSION
TERMINAL CONN,
TO INDUCTION COIL
\f CONTACT POINTS
BREAKER
Fig. 217. — North East breaker and distributor.
The distributor and breaker unit is usually carried on the front end of
the generator and driven at one-half crankshaft speed by the same shaft
which drives the generator. The distributor consists of a cap or head of
insulating material with one high-tension contact in the center and simi-
lar contacts, as many as there are cylinders, spaced equidistant about
the center. The distributor arm or rotor carries a contact button which
DISTRIBUTOR BRUSH
TO SWITCH
AND BATTERY
TEST LAMP
THISTERI1INAL'
GROUNDED
CONTACTS SHOULD OPEN Q.OZQ*
Fio. 21S. — Method of connecting test lamp to check time of contact opening.
makes continuous contact with the head and serves to direct the second-
ary current to the proper spark plug.
Beneath the distributor head and the rotor is the breaker, Fig. 220,
which is piovided with a timing adjusting screw in the center of the shaft.
The loosening of this screw allows the cam to be turned in either direction
to secure the proper timing.. The breaker operates on the closed cir-
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182
THE GASOLINE AUTOMOBILE
cuit principle and the spark occurs at the instant the timer contacts
open. The adjustment screw must always be screwed down tight after
J the cam is adjusted.
^* The distributor is equipped with both manual and automatic spark
control. The manual control is linked up with the spark lever on the
Packard. Cadillac.
Fiq. 219. — Types of Delco ignition equipment.
National.
steering wheel sector. This is for the purpose of securing the proper
retard of the ignition for the starting operation and very slow idling
speeds, and to secure the proper advance required for maximum power
at very low engine speeds over which the automatic feature has no
control;.
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BATTERY IGNITION SYSTEMS
183
The automatic spark advance mechanism is located in the lower part
of the breaker housing. This mechanism is for the purpose of securing
the additional advance that is required to give the best operating condi-
DIMMIN6
^S RESISTANCE
TO SPARK Pl.U« 3
, | , i
L&ewa.
.INDUCTION CO\l/
MOUMTeO OH GENCRATOn
INSULATED
BREAKER
(CONTACTS SWAP
open oie'To our
MANUAL ADVANCE
~ RETAAD LEVER
Fio. 220. — Wiring diagram for typical Delco ignition system for four- and six-cylinder
engines.
tions of the engine at the higher engine speeds. This feature makes it
unnecessary to manipulate the spark lever for ordinary varying engine
speeds in order to secure the best performance of the engine.
221. — Typical 1917 Delco ignition type generators.
The ignition coil is usually mounted on top of the generator as shown
in Pig. 221. It will be noticed that an ignition resistance unit is mounted
on one end, and that the condenser is placed in the bottom of the coil
with one side grounded. The switch button next to the ammeter, Figs.
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184
THE GASOLINE AUTOMOBILE
200 and 221, controls both the ignition circuit and the circuit between
the generator and the storage battery. It connects the three contacts
numbered (2), (4), and (3) in the circuit diagram. The second button
from the ammeter controls the cowl and tail light; the third button con-
6108ED CAM, ^K
PR/MARY - V* — —
TERMINAL ^^%TC\*
CONDENSER flAF
BREAKER POINTS
(Off RATE INPARAUtl)
Kt „ TIMING ADJUSTING
k V SCREW
Jfew
jBUI MANUAL SPARK
1 ADVANCE LEVER
iflf
RES/SrANC£^Utt^^KSHB&
r«fi75^
Fro. 222. — Deloo breaker mechanism used on Cadillac Eight, Model 57.
. trols the headlight bright; and the button on the extreme left controls the
headlight dim. The starting and lighting features of the Delco system
will be taken up in the chapter on starting and lighting systems.
DISTRIBUTOR GROUNDING
SCREW
CONDENSER LEADS
DISTRIBUTOR SPIRAL
I SEAR OILER
RES/STANCE UNITS
CONDENSER LEADS
DISTRIBUTOR
'DISTRIBUTOR
PRIMARY
TERMINAL
THREE LOBED CAM'
INTERRUPTER CONTACTS
PRIMARY
TERMINAL
DISTRIBUTOR
BEARING OILER
Fio. 223. — Delco breaker mechanism used on Packard twin six.
159. Delco Ignition Breakers for Eight- and Twelve-cylinder Engines.
— The breaker of the Delco equipment as used on the Cadillac "Eight"
is shown in Fig. 222 and that used on the Packard "Twin Six" in Fig.
223. These are typical of the many designs of breakers for eight- and
twelve-cylinder engines.
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BATTERY IGNITION SYSTEMS 186
On the Cadillac breaker, the cam has eight lobes and operates two
contact breakers at one-half crankshaft speed. These breakers are
connected in parallel, and are timed to open and close at the same time.
The object is to distribute over two sets the current which would other-
wise pass through one. This greatly reduces the wear and burning of the
points. In order to accomplish this, both sets of contact points should
be adjusted exactly the same, namely, to open .020 in.
On the Packard unit, there are two low-tension circuits and two
distributors. A separate breaker, coil, condenser, and distributor serve
each set of six cylinder. The breaker mechanism consists of a separate
set of circuit-breaker points for each low-tension circuit. These are
operated by a single three-lobed cam mounted on the top of a vertical
shaft which is driven at crankshaft speed. This causes each low-tension
circuit to be broken three times during each revolution of the crank-
shaft, thus providing the six necessary sparks for each revolution of the
crankshaft.
160. Timing Battery Ignition with the Engine. — The details con-
nected with ignition timing depend somewhat on the make and type of
system and also on the type of engine. The general principles, however,
are the same. The following rules for timing a four-cylinder engine,
with minor modifications to suit certain individual conditions, will apply
generally to all systems of the vertical unit closed-circuit type having
an adjustable cam.
1. Place the spark lever on the steering wheel in the fully retarded
position, making sure that the interrupter timer lever is fully retarded
and that all play in the connecting mechanism from spark lever to timer
has been taken up.
2. With the pet cocks open or the spark plugs removed, turn the
engine over slowly by hand. After noting the firing order, either by
testing the order of compression or by watching the operation of the
valves, turn the engine until the dead-center mark on the flywheel for
No. 1 and 4 cylinders (D.C. 1-4) is about 1 in. past dead-center posi-
tion with No. 1 cylinder (the cylinder next to the radiator) on the upper
end of its compression stroke. (One inch measured on the rim of a 163^
in. flywheel measures off about seven degrees of the crank angle.) In a
four-cylinder engine, the exhaust valve in No. 4 cylinder should be just
closed with this setting.
3. Remove the distributor head and loosen the timing adjusting screw
or nut in the center of the timer shaft. Turn the breaker cam so that the
distributor brush or button will be in the position under No. 1 high-
tension terminal when the distributor head is fastened in the proper
position. In this position, adjust the breaker cam carefully so that when
the distributor arm is rocked forward, taking up the slack in the gears,
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186 THE GASOLINE AUTOMOBILE
the contacts will be opened by the breaker cam, and, when the arm is
rocked backward, the contacts will just close.
4. Tighten the adjustment screw or nut securely and replace the
distributor arm and head. The head should be properly located by the
locating tongue and the hold-down clip. The distributor should be wired
to the plugs in the proper order of firing, beginning with No. 1 and pro-
ceeding around the distributor head in the direction of breaker rotation.
N*§1. Care of Battery Ignition Systems. — General rules which will
provide proper care and insure long life to practically all types and
makes of battery ignition systems are as follows:
Contact Points and Distributor. — The distributor cap should be re-
moved and the contact points inspected every 1000 to 1600 miles. If
found dirty or uneven and pitted, a fine flat file, or preferably a piece of
No. 00 sandpaper, should be passed between them. The contact points
have a standard opening of .017 to .020 in.
The Distributor. — The distributor cap will require no attention except
to wipe out from time to time any dust which may accumulate. This
may be done by using a rag moistened with gasoline.
Oiling. — Each bearing of the breaker distributor unit should be given
a few drops of clean cylinder oil every 1000 miles. Oil is much cheaper
than new bearings.
Every 1000 to 1500 miles a slight trace of clean oil or grease placed
on the fiber block or on the steel cam will keep the cam from rusting.
The contact points should not be oiled.
Wiring. — Once or twice each season all wiring, especially the high-
tension cables, should be thoroughly inspected and all wires with worn
or cracked insulation replaced with new. All terminals should be kept
tight. Care should be taken that each secondary wire is kept free from
oil and well supported so that there is no rubbing contact with the engine
frame. Short circuits and misfiring of the engine are thus avoided.
Spark Plugs. — Failure of ignition is usually due to dirty spark plugs.
When the engine does not fire regularly, the plugs should be examined,
and, if found to be sooted, they should be cleaned by scraping off the
carbon and washing them in gasoline. The opening of the plug gap
should measure .025 to .030 in., or the thickness of a worn dime. After
the plugs have been replaced in the cylinder, the porcelains should be
examined to be sure that they are not cracked.
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CHAPTER VIII
MAGNETOS AND MAGNETO IGNITION
162. Magneto Classification. — The magneto which is used very
extensively for ignition purposes on automobiles, trucks, and tractors,
consists essentially of two parts, a magnet type frame for supplying the
magnetic field and an armature which carries the winding and which
usually must revolve in this magnetic field in order to generate a current.
The magneto is built in two general types according to the methods
employed for generating the current, namely, the armature wound or
H-type and the inductor type. In the armature wound type the winding
generates current by revolving
in, and cutting, the magnetic
field. In the inductor type, the
winding in which the current
is generated is stationary and
the current is generated by the
reversal of the magnetism
through the coil and the cutting
of the winding by the lines of
force. The magneto may also
be classified either as high or
low tension, according to the
voltage of the current which it
generates. Both the high- and
low-tension magnetos may be
constructed on either the arma-
ture wound or inductor principle.
163. Magneto Magnets. — It is a well-known fact that either in a
bar magnet or in a magnet bent in the shape of a horseshoe, as in Fig.
224, the magnetism (that invisible force which attracts and repels iron
or steel) is concentrated near the ends, as indicated by the bunches of
iron filings at the ends of the magnets. One end of the magnet is called
the North or N-pole, and the other the South or S-pole. The difference
between the two poles can be seen by placing two like poles and again
two unlike poles together; it will be found that the like poles repel each
other and the unlike poles attract each other. This is the fundamental
law of magnetism.
187
Fig. 224. — Bar and horseshoe magnets.
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THE GASOLINE AUTOMOBILE
164. Lines of Force. — If a horseshoe magnet be placed on its side, as
shown in Fig. 225 A, with a piece of paper over it, and iron filings sprinkled
over the paper, it will be found that the filings arrange themselves in
well-defined lines. This arrangement indicates that there is a magnetic
force acting between the two poles of the magnet. The influence which
two horseshoe magnets (such as used on magnetos) have on each other
when laid side by side is clearly shown in Fig. 225, B and C. In Fig. 225B
two magnets are arranged in a vertical position to show the magnetic
flux between the pole ends when properly assembled; while at C, Fig.
225, the magnets are incorrectly assembled, the north end of one magnet
lying next to the south end of the other, thereby greatly reducing the
number of lines of force that would be cut by an armature rotating
■ > ■ i
& lii
Fiq. 225. — Magnetic field shown by iron filings.
between the poles. In placing the magnets on a magneto, great care
must be taken to get all the north poles together and all the south poles
together. An easy way to make sure of this, before putting the magnets
on the magneto, is to lay the magnets together so that the poles will
repel each other.
165. Types of Magnets. — In some types of magnetos, compound per-
manent magnets are used. A compound magnet is one built up of several
simple magnets arranged with like poles together, as shown in Fig.
226. It has been found that a compound magnet is usually stronger
than a simple magnet of the same size, and more desirable. The number
of magnets required to produce the desired magnetic field strength de-
pends to a great extent on both the kind and quality of the steel used in
the magnets. At the present time, chrome or tungsten steel is most
generally used, so that two magnets arranged as shown in Fig. 2262? are
usually found sufficient. It is generally recognized that the magnetic
pull of each magnet should be such as to sustain a weight of at least 15
lb. in order to give satisfactory service.
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MAGNETOS AND MAGNETO IGNITION
189
166. Mechanical Generation of Current. — It has been found that if
a wire be moved across the magnetic field between the poles of a magnet
so as to cut the lines of force there will be an electric current generated
Simple magnet
A.
Double magnet
B.
Fio. 226.
Compound magnet
C.
in the wire. If the wire should then be moved across the lines of force
in the opposite direction the current would again flow in the wire but
in the opposite direction. The exact reason for the generation of current
is unknown, but it is a well-known
fact that cutting magnetic lines of
force by moving a wire across them
will generate current in the wire.
The process of generating a current in
this manner is known as induction,
and the current thus produced is
termed an induced current.
The fact that current can be
generated through induction is made
use of in the magneto generator, an
elementary type of which is shown in
Fig. 227. The wire is formed in the
shape of a rectangle and arranged to
rotate between the pole pieces of the
magnet. If the ends of the wire are
connected to a measuring instrument,
a current of electricity will be found
to flow out of one end of the wire
and into the other end, as the wire
is revolved. In the position shown, with the loop rotating in a
clockwise direction, the current flows out at B and in at A. If the loop
ROTATING ARMATimt
Fig. 227. — Mechanical generation of
current.
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190
THE GASOLINE AUTOMOBILE
of wire is turned through a complete revolution, it will be found that the
current generated will alternate in direction, making one complete rever-
sal in one revolution of the wire. This is due to the wire cutting the
magnetism first in one direction, then the other. When the wire is
cutting the lines of force at right angles, the voltage is the maximum, and
it is at this period of rotation that the current is best for ignition purposes.
This condition occurs twice during a complete revolution of the loop of
wire. The position for maximum induced voltage is at A-B, while the
position for no induced voltage is at A'-B'. In this position the wire is
traveling parallel to the magnetism and is not cutting lines of force.
After passing the vertical position, the side of the loop A will cut the
magnetic lines of force in the opposite direction, causing the induced
current in the wire to reverse, flowing out at A instead of B.
In the actual magneto, instead of only one turn of wire, a great many
turns of wire are wound in the shape of a coil around a piece of laminated
Fio. 228. — Flow of magnetic field through H-type armature.
iron, called the armature core. This coil is caused to rotate between the
magnetic poles. This rotation of the coil generates a current in it.
Figure 228 illustrates the change and cutting of the magnetic lines of
force during one complete revolution of the armature. By using the
laminated iron armature core, the strength of the magnetism flowing be-
tween the poles of the magnet is increased, thus increasing the number
of lines of force that are cut by the coils of wire.
167. Low-and High-tension Magnetos. — A low-tension type of mag-
neto is one which delivers current of a low voltage. This current must
be converted to the necessary high voltage for ignition by an external
induction or transformer coil. The armature contains only a primary
winding, while the transformer coil has the usual primary and secondary
windings.
A high-tension magneto delivers current from the armature at suffi-
ciently high voltage for ignition, without the use of an external transformer
coil. The high-tenfcion current is generated by the combined action of
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MAGNETOS AND MAGNETO IGNITION 191
two windings on the armature of the magneto, one a primary winding,
and the other a secondary winding. The armature assembly also con-
tains a condenser. The true high-tension magneto must not be confused
with the so-called high-tension magneto in which the armature current is
transformed by a coil placed in the top of the magneto, instead of out-
side as is done in the low-tension type. The coil is contained in the
magneto assembly merely for convenience, but this does not make it a
high-tension magneto in the correct sense of the term.
168. Armature and Inductor Type Magnetos. — An armature or
shuttle-wound type magneto is one in which the lines of force are cut by
means of a coil of wire wound on an armature or shuttle rotating between
the magnetic pole pieces, as just described. It may be of either the
high- or low-tension type.
In an inductor type magneto, the coil of wire is stationary. The
cutting of the lines of force by the stationary coil is caused by a revolving
inductor. Since the coil in which the current is generated is stationary,
this avoids the necessity of having sliding contacts and brushes in order
to connect the coil with the external circuit. The inductor-type magneto
may also be either low or high tension. The constructional features
of these two general types will be pointed out in considering the several
types of modern magnetos.
169. Current Wave from a Shuttle-wound Armature. — Figure 229
shows a typical curve of the current generated in the winding of a shuttle-
wound armature as it turns through one revolution. In Fig. 230 are
shown the positions of the armature corresponding to the points, A, B,
C, Dy and E of Fig. 229. In position A the flux is passing through the
armature in one direction, while in position E, after turning 180°, the
flux is in the other direction, because the armature has turned around.
During the remainder of the revolution, from position E around to posi-
tion A, the current generated will be opposite in direction to that gen-
erated during the first half of the revolution. The current generated
during the first half of the revolution is shown in Fig. 229 by the height of
the curve above the base line, while that generated during the second
half is shown below the line.
The exact positions of the armature at which the strongest electrical
impulse can be obtained, and also the shape of the current wave, depend
upon the shape and construction of the pole pieces and armature core,
as well as upon the speed of rotation and the strength of the magnets.
Any change in one of these factors will produce a change in the electric
pressure at the terminals of the armature winding.
Most magnetos that are run at variable speeds are constructed so
that a strong current can be produced throughout a considerable range
of position of the armature. This is done to allow for the advance and
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192
THE GASOLINE AUTOMOBILE
retard of ignition relative to the position of the pistons, as well as to
allow for the lag of the current in the armature with regard to the position
of the armature at the instant of maximum impulse or voltage. This
current lag for the speeds in usual practice is small, so that in general
the positions of the armature for the maximum current are about as
indicated in Figs. 229 and 230.
It is evident from the current wave diagram of Fig. 229 that, whatever
the system of ignition with which a low-tension magneto is used, the
Fig. 229. — Typical curve of current from shuttle armature.
best spark will be produced only during the angle of rotation in which
the current generated is at or near its maximum. When the armature
is in position C, Fig. 230, the current is at its maximum and the spark
will be strongest. As the armature rotates from position C to D the
curve, Fig. 229, decreases $lowly in height; hence, during this period the
current produced is most favorable for ignition purposes. Position C
would correspond to extreme advance and D to extreme retard for this
A-0*
B-65' C-86* D-186'
Fig. 230. — Armature positions of Fig. 229.
!- lso-
magneto, giving a spark range of about 40° of armature rotation. It is
evident from the shape of the curve that a position of advance beyond
C or of retard beyond D would give a spark too weak for ignition purposes
or no spark at all. This shows the necessity of having an alternating
current magneto gear-driven from the engine shaft, so that the armature
will always be in the proper position with relation to the engine pistons.
The curve of Fig. 229 also shows that there are two points in a revolution
of this type of armature during which a spark can be obtained, namely,
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MAGNETOS AND MAGNETO IGNITION
193
between C and D as just mentioned and at a similar position 180° later,
when the current is in the other direction. Consequently, the magneto
with an H-type or shuttle-wound armature, ordinarily used for automo-
bile ignition, gives two sparks per revolution of its armature. Because
of this, the armature speed of a magneto must have a definite relation
to the number of cylinders of the engine. In a four-cylinder four-stroke
engine the armature must revolve at crankshaft speed in order to pro-
duce four sparks during two revolutions of the engine crankshaft. On a
six-cylinder four-stroke engine the armature must make three revolu-
tions during two revolutions of the crankshaft, or it must turn at one
and one-half times crankshaft speed.
^%
"iJ [h w rJ
tstributor T_
Distributor
(on Magneto! '
Fig. 231. — Low-tension magneto ignition system with interrupted primary current.
170. Low-tension Magneto Ignition System with Interrupted Primary
Current — In this type of ignition system, the current is supplied at low
voltage by a low-tension magneto and is stepped up to a high voltage by
an induction coil similar to the non-vibrating coil used with a battery
ignition system. The mechanical interrupter for the primary or low-
tension current, and the distributor for the high-tension current, are
provided on the magneto. Figure 231 shows this system in its simplest
form. A magneto with a shuttle-wound armature is shown, although a
magneto of the inductor type could be used as well. One end of the arma-
ture winding is grounded to the metal of the armature as is usual in mag-
neto construction. The current is collected from the other end of the
winding by a collector ring and brush which are not shown. The inter-
13
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194 THE GASOLINE AUTOMOBILE
rupter is shown separate, but it is always mounted on the magneto shaft
so that the time of opening the circuit is in proper time with the period
of greatest current flow in the armature winding. Assuming the inter-
rupter contacts to be closed, the low-tension current generated in the
armature winding flows through the switch and the primary winding of
the coil and through the interrupter to the ground (on the armature
shaft) and back into the armature winding. During the next half revolu-
tion of the armature, the current in the circuit is in the reverse direction.
At the desired time for the spark, which must be during the period of
maximum current flow, the primary circuit is broken at the interrupter.
This is caused by the high point of the cam raising the interrupter lever
from its contact with the fixed contact point. A condenser placed in
parallel with the interrupter absorbs the induced current in the primary
winding, caused by this sudden interruption of the current flow, and
assists in rapidly breaking down the magnetism of the coil core, in the
same manner as in a battery ignition system. By this action, a high-
tension current is induced in the fine secondary winding of the coil. The
distributor, which is mounted on the magneto, receives this current at
its central connection and directs it to the proper plugs.
The secondary winding of the coil, as shown, is entirely separate
from the primary and has its own ground connection. This is not neces-
sary, as the two coils could be connected at their upper ends and the sec-
ondary ground be made through the armature to the grounded end of
that winding. The connection to the distributor would then be made
from the other end of the secondary winding.
Instead of having the switch in series with the armature, and the
circuit through the coil and interrupter, so that opening the switch
breaks the circuit, the switch connection might be from the insulated
side of the circuit to the ground. In this case the circuit would be through
the coil and interrupter when the switch was open. When the switch
was closed, the current would have a permanent and easy path to the
ground and back into the armature, so that practically no current would
flow through the coil and interrupter. In this case, closing the switch
would ground the primary current so that the coil would become inopera-
tive and ignition would cease.
The interrupter cam has two lobes corresponding to the two current
waves produced per revolution in the shuttle type of armature and also
in some magnetos of the inductor type. This arrangement is used when
the number of cylinders is such that each current wave can be used for
the production of a spark and is common for four- and six-cylinder
engines.
171. Low-tension Magneto Ignition System with Interrupted Shunt
Current. — The interrupter in this system is not in series with the circuit
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MAGNETOS AND MAGNETO IGNITION
195
through the primary winding of the coil, but is in a shunt or cross con-
nection as shown in Fig. 232. This system is the one commonly used
when a low-tension magneto is employed for ignition. The primary
current has two possible paths, either through the interrupter, if that is
closed, or through the primary winding of the coil. The current naturally
takes the easy path through the interrupter, when that is closed, there
being practically no current through the coil at this time. When the
magneto armature reaches the desired position for the spark, which is at
some point during the period of maximum current flow, the interrupter
is opened. This sudden interruption of the current through the shunt
circuit, combined with the action of the condenser, produces an induced
Spark Plugs
"I"
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/^
Distributor
(on Mognetpf
Fio. 232. — Low-tension magneto ignition system with interrupted shunt current.
current in the armature circuit, and this, having no other path, rushes
instantly through the primary winding of the coil. This sudden current
through the primary winding induces a powerful momentary voltage in
the secondary winding, and this voltage is used for the production of the
spark at the plugs.
It will be noted that the spark from this type of magneto is produced
by the building up of the magnetic field of the coil instead of by the break-
ing down of the field as in the interrupted primary system previously
described. For this reason, and also because of the resemblance of its
action to that of the ordinary transformer, the coil is sometimes called
a transformer coil. An induced voltage is created in the secondary of any
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196 THE GASOLINE AUTOMOBILE
coil when the magnetic field is built up as well as when it is broken down.
In battery ignition systems, however, the action of building up is com-
paratively slow, and the induced current is, therefore, not of sufficient
voltage to be used. In the interrupted shunt-type magneto, the coil
winding of the armature, coupled with a condenser of proper capacity,
produces on the break of the shunt circuit by the interrupter, an impulse
of current of sufficient power to magnetize the coil very rapidly and to
give the desired induced voltage in the secondary winding.
After the armature has passed the position of maximum current, the
interrupter is closed and the armature again has the easy shunt path
through which to build up its current when it again rotates into the
position of maximum current.
As shown in the diagram of Fig. 232 the coil has a common ground
connection for the two windings, making three terminal connections for
the coil. The switch and coil are usually mounted as a unit on the dash.
The collector brush on the magneto is connected to the switch on the coil.
There is also a connection from the switch in the coil back to the insulated
contact point on the interrupter and another connection from the primary
winding of the coil back to a grounded binding post on the magneto frame.
The secondary terminal of the coil is connected to the central post on the
distributor. This makes four connections when the switch is on the coil,
although there are really only three coil connections. When a battery is
used for starting purposes, another connection is added to the switch, and
sometimes two if the one side of the battery is not grounded directly.
The condenser may be placed either in the coil box or may be built in
the magneto. The switch may be placed in series with the connection
from the armature to the coil and interrupter, as shown, or it may be
arranged to ground the armature current permanently so as to short-
circuit the current from the coil and interrupter, thus rendering them
inoperative. In this latter connection, closing the switch cuts off the
ignition current, while opening the switch permits the ignition to operate.
A safety gap is also provided, either at the coil or at the magneto.
172. Dual Ignition Systems. — The majority of the low-tension magne-
tos of the type just described are provided with an arrangement for using
battery current for starting purposes when the magneto current is small,
due to the low rotative speeds. The batteries can also be used for con-
tinuous running in cases of emergency, although the life of the batteries
in this case is usually short because of the long contact at the interrupter,
which wastes the battery current. The connections at the switch are
usually made so that when the battery is used, the interrupter is in series
between the battery and the coil; then the spark is induced by the inter-
ruption of the battery current through the coil. In some of the dual
systems, the switch is provided with a push-button operating a vibrator
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MAGNETOS AND MAGNETO IGNITION
197
or interrupter in the battery circuit, so that a spark can be produced
without turning the engine. This enables the operator to start the engine
on the spark if there is an explosive charge in the cylinder.
173. Splitdorf Low-tension Dual Ignition System with Type T Mag-
neto.— The Splitdorf low-tension magneto ignition system is a typical
dual ignition system of the interrupted shunt current type. Figure 233
shows the model T magneto and Fig. 234 the circuit wiring of this mag-
neto with the typical box-type induction coil which is mounted on the
dash. The magneto is of the armat.re wound type having a single
winding. The switch on the coil box has three positions, "Off," "Bat-
tery," and "Magneto." The figure shows the switch dotted in on the
"Magneto" position. The armature current is led from the collector
brush A, which is mounted in the breaker cap and which rubs on an in-
sulated button on the end of the
armature shaft extending through
the cam, to the coil box terminal A
and to the lower right switch button,
as indicated by the arrows. From
there, the current has two paths back
to the magneto ground. One path is
by the way of No. 2 terminal over the
breaker points which are normally
closed; the other, through the primary
winding of the coil to the grounded
No. 3 magneto terminals. With the
contacts closed, practically all of the
primary current will flow across the
breaker points, owing to the fact
that the resistance is much less than
that through the primary coil wind-
ing. When the points open, this path is broken and there will be a
sudden rush of current through the primary winding of the coil. The
action of the primary current combined with the discharge from the
condenser induces a high-tension current in the secondary winding of
the coil. This high-tension current is directed to the proper plug by
the distributor on the magneto. A safety gap is provided on the top
of the coil box.
With the switch on the "Battery" position the magneto is disconnected
and the dry cells connected to the primary circuit. It will be found
that when operating on the battery, the coil and breaker are in series
and the system operated as an interrupted primary current system. The
secondary circuit will be the same as when operating on the magneto,
namely, from the high-tension terminal on the coil to the distributor, to
Fig. 233. — Splitdorf low-tension
magneto, Model T.
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198
THE GASOLINE AUTOMOBILE
the plug, to the ground and returning to the secondary winding over the
primary wire connected to No. 3 grounded terminal.
The condenser is mounted in the coil and is connected so as to protect
both the magneto interrupter points and the push-button contacts on
the switch.
The push-button contacts are in the primary circuit in series with the
coil, and are normally closed. When the switch is thrown on "Battery"
position and the breaker points are closed (which they normally are) the
primary circuit will be completed and the coil magnetized by current from
the dry cells. If the push-button is pressed and the contacts opened,
DRY CELLS
TO SPARK PLUGS
SAFETY OAP
SWITCH*
INSULATED TERMINAL ON BREAKE*
BOX COVER WITH BRUSH ON INSIDE
WHICH MAKES RUB BINS CONTACT
WITH INSULATED BUTTON ON CNQ
OF ARMATURE SHAFT.
Fig. 234. — Wiring diagram of Splitdorf low-tension dual ignition system.
the primary current will be interrupted, causing a sudden demagnetizing
of the coil and creating a secondary spark in the cylinder which is lined
up to fire in accordance with the position of the distributor arm. If the
cylinder should contain a combustible mixture, it is possible that a spark
caused in this manner would ignite the mixture and create sufficient
explosion pressure to kick the engine over, causing it to start without the
usual cranking.
174. Remy Inductor Type Magneto. — The Remy Magneto Model
RL, as shown in Fig. 235, is a typical low-tension magneto of the inductor
type. Figure 236 shows the inductor and coil, while Fig. 237 shows the
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MAGNETOS AND MAGNETO IGNITION
199
coil and the shaft in their places with respect to the pole pieces, the
magnets and the shaft bearings having been removed. The two wing-
shaped inductors are mounted on a steel shaft and are revolved on either
side of the stationary coil. Figure
238 shows the path of the magnetism
during one complete revolution of the
inductor.
When the inductors are in the
horizontal position, the flux enters
one inductor, makes a right-angled
turn, passes along the shaft and
through the coil to the other induc-
tor and then to the other pole piece.
In this position, the same condition
exists as when an armature of a
shuttle type is in the horizontal posi-
tion. When the inductors are re-
volved to the vertical position, the
flux passes from one pole piece di-
rectly across through the inductors to
the other pole piece, and there is no flux through the coil. This change,
therefore, produces a voltage in the coil winding. The outer ends of
the inductors are of such length that when they are in the vertical posi-
tion, they offer a direct path from one pole to the other, but when they
are horizontal, the flux must enter the one inductor, pass through the
center of the coil, and out through the other inductor.
Fiq. 235. — Remy magneto, Model RL
-Remy inductors and stationary coil.
Fig. 237. — Remy inductor shaft and
coil assembled in pole pieces and base.
This magneto will produce two current waves per revolution in the
same manner as the shuttle type. The current produced is also an
alternating current, as the direction of the flux through the coil is reversed
each 180° of revolution of the shaft. Due to the design of the parts, the
current wave has an abrupt rise and fall with an almost flat top, making
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THE GASOLINE AUTOMOBILE
possible a large timing range (35°) with practically the same intensity
of spark. This magneto is used for jump-epark ignition, the low-tension
A B C D E
Fio. 238. — Path of magnetic flux through Remy inductor during one revolution.
current generated in the coil being used with a circuit breaker and a step-
up transformer coil. The secondary current from the transformer is led
IX Itetav KkM wHk tlput Xrtutad •
▲4ju* *• OMtert ttaNv «rt a |«* B
Fig. 239. — Circuit breaker of Remy magneto.
to a distributor on the magneto and is there distributed to the different
plugs of the engine. The circuit breaker, Fig. 239, is mounted on the
magneto and operated by a cam on
the end of the armature shaft, the
^M ^k cam being mounted so as to break
M ■ the circuit in proper relation to the
position of the armature for maximum
^^^^1 current. The condenser, Fig. 240,
^^^^T "*^^^ is mounted in the arch of the mag-
Ip^P nets and is connected directly across
the breaker points.
Figure 241 shows an external
wiring diagram of the model RL mag-
neto with type LE switch and coil, while Fig. 242 shows a diagram of the
internal circuits. The lettering on the coil — Y, R, and G — indicates the
Fig. 240. — Condenser for Remy Model
RL magneto.
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MAGNETOS AND MAGNETO IGNITION
201
color of the wire intended by the manufacturer to be connected to that
terminal. The wiring from the coil to the magneto is connected as
follows:
Fiq. 241. — External wiring diagram of Remy magneto, Type RL.
Red (R) wire goes to ground binding post on timer end bearing.
Yellow (Y) wire goes to contact screw post on circuit breaker.
Green (G) wire goes to insulated screw post on the timer end bearing.
INDUCTION
CO
s=J^
MJ4M BUTTON
■ AT Mir CONTACTS
BAT. MAG. Chormaily WO()
SWITCH
fSWITCH MOWN DOTTED
ON WT. AND MAO POSITION
DRY CELLS
— GROUND
BREAKER
TERMINAL.
Fiq. 242. — Internal circuit diagram of Remy magneto, Type RL.
Timing. — For timing this magneto, turn the engine over by crank
until No. 1 piston reaches top dead center on compression stroke.
Press in on the timing button at the top of the distributor and turn the
magneto shaft until the plunger of the timing button is felt to drop into
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THE GASOLINE AUTOMOBILE
the recess on the distributor gear. With the magneto in this position
couple it to the engine. Pay no attention to the circuit breaker when
coupling or setting gears, as the breaker is automatically brought into
the correct position, and the distributor segment is in contact with No. 1
terminal. This No. 1 terminal is plainly marked on the distributor.
175. The Ford Ignition System. — The Ford magneto may be classed
as a high-frequency, alternating-current magneto of the inductor type.
It serves merely as the source of primary current for an ordinary vibra-
ting-coil type of ignition system. The construction of the magneto is
shown in Figs. 243 and 244, while the wiring diagram is shown in
Fig. 245.
Magneto Coil Spool
Copper Wire —
End of Ribbon 1
Grounded Here f
To Coil
Magneto Coil Support
Fig. 243. — The Ford magneto.
The stationary and revolving elements are interchanged from the
customary relation. The armature coils are stationary and the magnets
revolve. The armature consists of 16 coils which are attached to a
stationary supporting disc in the flywheel housing. An equal number of
permanent magnets of the horseshoe or V type are secured to the flywheel
through non-magnetic studs. The magnets revolve with the flywheel at
a distance of J-^2 ln- from the coils. The North poles of two adjacent
magnets are fastened together, likewise the next pair of South poles.
When a pair of North poles is in front of the core of one of the coils, the
magnetic flux will flow in through the core, through the supporting coil
plate, and out through the core of the adjacent coils to the South poles
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MAGNETOS AND MAGNETO IGNITION
203
as shown in Fig. 244. When the flywheel makes Ke revolution this
flow is reversed. Thus, 16 current waves are generated per revolution of
the flywheel. The coils are all connected in series with one end of the
winding grounded and the other end connected to an insulated binding
post on the top of the flywheel housing. This post is connected through
the switch to all four induction coils by means of a contact plate in the
bottom of the coil box as was shown in Fig. 180, Chapter VII. The other
ends of these coils are connected to the four posts of the timer mounted
on the front end of the camshaft. Since one end of the magneto winding
is grounded, and since the timer completes the circuit to the ground from
each induction coil in proper order, it follows that the magneto current
will pass through whichever induction coil is grounded at the timer.
The induction coils are of the ordinary double wound induction t^pe
with vibrators to interrupt the primary current from the magneto. A
TO MA6NCTO TOWINAC
ON COIL ©OX.
MAfiftCTO CONTACT ON
FlYWHEEl. HOUSING '
c
C0H.«*LATC BOLTED
>W *CA» CNO OC
CRANK -CASE.
Fig. 244. — Diagram showing scheme of Ford magneto.
diagram of the Hienze-Ford coil is shown in Fig. 246. The secondary of
each coil has a direct connection to the plug of one of the cylinders with
a grounded return.
This magneto is quite unlike those previously described in that the
current waves are of high frequency and are not all used for ignition.
The magneto itself does not have to be timed to the engine. The alter-
nations of the magneto current are frequent enough to cause only a
slight variation in the instant of ignition as affected by the periods of no .
current. The length of contact in the timer is sufficient to overlap from
one current wave to the next. In case the magnet is in a position where
no current is generated when the timer first makes contact, there will be
a lag of a very few degrees in the spark until the magneto has turned into
a position where it will generate sufficient current to operate the coil.
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THE GASOLINE AUTOMOBILE
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MAGNETOS AND MAGNETO IGNITION
205
Due to the shape of the current waves, the greatest possible lag due to this
cause is probably not more than 5° on the engine crankshaft.
176. The High-tension Magneto. — Under the name of High-tension
Magneto are included all magnetos which generate, directly in the mag-
neto winding, a current of sufficiently
high voltage for jump-spark ignition with-
out the aid of a separate induction coil.
The magneto winding contains both a
primary and secondary winding, similar
to the winding of a non-vibrating type in-
duction coil, instead of the usual single
winding found in the low-tension magneto.
In the high-tension magneto is also incor-
porated the interrupter, distributor, and
condenser, so that the magneto contains
within itself all the essentials of a complete
ignition system, the only necessary out-
side parts being the spark plugs and the
This applies to both the armature wound
jortmctf
*"S
j[*0* maghcto
7m*u switch.
Fig. 246. — Diagram of Ford-
Heinse induction coil.
magneto controlling switch.
and the inductor type of magneto.
177. The Bosch High-tension Magneto. — The Bosch Magneto, Figs.
247 and 248, is a typical high-tension magneto of the armature wound
BOSCH HIGH
TENSION MAGNETO
Fio. 247. — Bosch high-tension magneto installation on M arm on engine.
type. The armature or rotating element, Fig. 249, is mounted on ball
bearings supported in the end housings and rotates between the magnet
pole pieces shown in Fig. 250. The armature, a cross section of which
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THE GASOLINE AUTOMOBILE
CNL COVER
SAFETY SPA UK
«ETA(NIN8 5P»H'
HIGH TfHSION
COLLECTOR 6AU3M\
APMATUBE COVER PLATE
CML MOLE COVER
MAGNETO COUPLING
DUTRI5UT0R
' fi MM MM
SAFETY SPARK
GAP HOUSING
COVER
BAM P1ATL
Fig. 248. — View of driving end of Bosch high-tension magneto.
ARMATURE
DRIVE GEAR
HARD
BINDING ARMATURE RUBBER
WIRES /CORE
METAL SUPRIN6
SEGMENT
INTERRUPTER END
ARMATURE COVER SERV-
ING ALSO AS CONDENSER
HOUSING
ECONDARY LEAD
TO SLIPRING
DRIVING END
ARMATURE COVER
Fig. 249. — View of armature of Bosch DU4 high-tension magnetos showing ball bearings
on armature shaft and pinion that drives distributor gear.
-MAGNETS
.-POLE
PIECES
ARMATURE
6R0UND BRUSH
BASE OF NON-
MAGNETIC METAL
Fiq. 250. — Magneto and pole pieces of Bosch magneto.
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MAGNETOS AND MAGNETO IGNITION
207
is shown in Fig. 251, consists of a soft iron core, a primary winding of
comparatively few turns of coarse wire, a secondary winding of many
turns of fine wire wound on the outside of the primary, and a condenser.
The condenser, Fig. 252, is mounted in one end of the armature housing
and connected so as to protect the interrupter points, the interrupter or
SECONDARY OR HIGH
TENSION WINDING
LAMINATED
ARMATURE CORt
INSULATI
Fiq. 251. — Cross-sectional view of Bosch high-tension magneto armature.
circuit breaker being mounted on one end of the armature shaft and
revolving with it. The cams for actuating the interrupter points are on
the inside of the interrupter housing. This arrangement is the reverse of
that of the usual low-tension magneto which has the cam on the armature
CLIP FOR FASTENING GROUNDED SIDE
OF CONDENSER TO INTERRUPTER END
OF ARMATURE COVER
FOR INSULATED
INTERRUPTE
RETAINING SCREW
BRASS PLATE
CONNECTION FOR INSULATED
END OF PRIMARY ARMATURE
WINDING
Fig. 252. — Condenser of Bosch DU4 high- tension magneto.
shaft and the interrupter in the housing. By having the interrupter,
condenser, and primary winding all on the armature, the entire primary
circuit is thus contained in the armature, forming a very compact and
efficient unit. One end of the primary winding is grounded on the
armature core, and the live end brought out to a circuit-breaking device.
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THE GASOLINE AUTOMOBILE
The grounded end of the secondary winding is connected to the live end
of the primary winding so that one is a continuation of the other. The
magneto armature core is grounded to the magneto base by the ground
brush shown in Pig. 253.
GROUNDING BRUSH
GROUND
CONNECTION TO
BASE PLATE
GROUNDING BRUSH
RETAINING SPRING
BASE PLATE-
Fia. 253. — Bottom view of magneto base plate showing ground brush.
During certain portions of the rotation of the armature the primary
circuit is closed, and the variations in magnetic flux have the effect of
inducing an electric current in the winding. When the current reaches
a maximum, which will occur twice during each rotation of the armature,
the primary circuit is broken, and the resulting armature reactions
produce a high-tension current of
extreme intensity in the secondary
winding. This current is trans-
mitted to the distributor by means
of which it passes to the spark plugs
in the cylinders in their proper order
of firing.
The Bosch DU4 high-tension
magneto is shown in Fig. 254, while
a longitudinal section and the rear
view with the breaker cover removed
are shown in Fig. 255. Figure 256
is a circuit diagram for the magneto.
Magneto Interrupter. — The mag-
neto interrupter mechanism is
mounted on a circular disc which is held rigid to the armature shaft
by the interrupter fastening screw. The relative position of the inter-
rupter to the armature is fixed by a keyway in the end of the armature
shaft which is taper bored. As may be seen in Fig. 256, the fastening
screw also forms the electrical connection between the stationary (insul-
ated) half of the interrupter and the primary winding of the armature.
30SCH
Fiq. 264. — Bosch high-tension magneto,
Type DU4.
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MAGNETOS AND MAGNETO IGNITION
209
This fastening screw also makes connection with the insulated terminal
of the condenser, the other terminal of which is grounded as are also
one end of the primary winding and the movable contact arm of the
interrupter.
Twice during each revolution of the armature, the primary circuit
closes and opens, this being caused by the fiber block on the interrupter
lever striking the two steel cams on the inside of the interrupter housing.
When the interrupter is not being acted upon by the cams, the interrupter
points are normally held closed by spring tension, consequently the
Longitudinal section.
1. Brass plate for connecting the end of the
primary winding.
2. Fastening screw for magneto interrupter.
3. Contact block for magneto interrupter.
4. Magneto interrupter disc.
5. Long platinum screw.
6. Short platinum screw.
7. Flat spring for magneto interrupter lever 8.
8. Magneto interrupter lever.
9. Condenser.
10. Collector ring.
11. Carbon brush.
12. Brush holder for same.
13. Terminal piece for conducting bar 14.
14. Conducting bar.
Rear end interrupter cover removed.
15. Distributor brush holder.
16. Distributor carbon brush.
17. Distributor plate.
18. Central distributor contact.
10. Brass segment.
20. Knurled nut on terminal stud.
21. Steel segment.
22. Dust cover.
24. Knurled nut on grounding terminal stud.
25. Holding spring for distributor plate 17.
116b. Interrupter housing and timing arm.
117. Cover for interrupter housing.
118. Conducting spring for grounding terminal stud.
119. Holding spring for interrupter housing cover.
Fig. 255. — Construction of Bosch high-tension magneto, Type DU4.
primary circuit is also closed. It is very important in this type of in-
terrupter that the interrupter lever unit be very accurately balanced on
its pivot to insure proper optening and closing of the points at high rotat-
ing speeds. The interrupter points are made of platinum and should
be adjusted to open .012 in. to .015 in. on engines of normal
compression.
Principle of Operation. — The function of the interrupter or breaker
is to interrupt the circuit of the primary winding of the armature when a
high-tension spark is to occur at the plug, the action in the armature
being similar to that of an induction coil. This interruption must take
14
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THE GASOLINE AUTOMOBILE
1 ui ou
w D -
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MAGNETOS AND MAGNETO IGNITION
211
place when the flow of current through the primary winding is at or near
its TnAYiTniiin value, which occurs \yiien the armature core is approxi-
mately in a vertical position, as shown in Fig. 256, the same as in the
low-tension magneto. In this position the corner of the armature is
just leaving the corner of the pole pi<ce and the winding is cutting the
greatest number of magnetic lines of iiOrce. In Bosch magnetos, having
a variable spark advance, the interrt^>ter points are timed to open when
the corner of the armature has left*l\e corner of the pole piece about
He »*•> with *he interrupter housing in full advance position. The
timing lever may be advanced aba it 35°; then, when the interrupter
housing is fully retarded, the armj1" ire has passed the pole piece about
% in. Thus the best spark is obt^.ned with the interrupter in full ad-
A B c
Fio. 257. — Distribution of magnetic flux through magneto armature core for various
positions.
vance position, which is the normal operating position at high engine
Figure 257 A, Bf and C shows the distribution of the magnetic flux
through the armature core for various armature positions. Owing to
the rotation of both primary and secondary windings of the armature and
the consequent cutting of the magnetic lines of force by both windings,
a voltage is generated in both the primary and secondary circuits pro-
portional to the number of turns in the two windings. During the period
of rotation, when the magnetic field is passing through the armature
core, the interrupter points are closed, thus completing (by short-
circuiting) the circuit through the primary winding. The current thus
generated in the primary winding will flow around the core, causing the
core to become magnetized in a cross direction as shown in Fig. 258.
At approximately the instant when the generated voltage is greatest,
the interrupter breaks the primary circuit thus permitting the armature
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THE GASOtilNE AUTOMOBILE
core to demagnetize instantly. IJiis causes a high voltage to be induced
in the secondary winding in the s&me direction as the generated voltage.
The induced current produced by the interruption of the primary circuit
lasts a very short interval of time art 1, if acting alone, would produce but a
single flash at the spark plug. H ^wever, owing to the revolving of the
secondary winding in the magnetic field, a more continuous current of
not so high a voltage is generatecT This generated voltage alone is not
sufficient to break down the resistance of the gap in the spark plug, but
at the instant the primary circuit I interrupted, the induced current is
sufficient to break down this resis^ nee and then the somewhat lower
voltage of the generated current is a"T le to cross the gap, thus producing
SECONDARY WIRE
GROUNDED TO PRIMARY
V-.INTEI
>CONDENSER
INTERRUPTER
CONTACTS
HORMALUY CLOSED
Fig. 258. — Diagram showing armature cross-magnetisation due to current generated in
primary and secondary winding.
not an instantaneous flash but a hot flame which lasts for a considerable
period of armature rotation.
Condenser. — The condenser, as in all high-tension armature-type
magnetos, is located in one end of the armature. It is connected in
parallel with the primary winding and the interrupter circuit. As stated
previously, the purpose of the condenser is to absorb the induced charge
in the primary winding and prevent the discharge of this current across
the interrupter points. The charge in the condenser surges back into
the primary winding in the opposite direction to that of the primary cur-
rent, thereby causing a more rapid demagnetization of the armature
and, consequently, producing a higher voltage in the secondary winding
than would otherwise be obtained.
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MAGNETOS AND MAGNETO IGNITION 213
In the diagram shown in Fig. 256, it will be seen that one end of the
secondary winding is connected to the insulated end of the primary
winding so that the one forms a continuation of the other. The other end
of the secondary winding leads to the collector ring or slip ring on which
slides a carbon brush, insulated from the magneto frame. The secondary
current is conducted from the brush to the center distributor contact
and from there through the carbon brush, carried on the distributor
gear wheel, to the various cable connections and spark plugs in their
proper order of firing. After jumping the spark-plug points, the current
then returns through the engine frame and the ground brush in the base
of the magneto, Pigs. 250 and 253, to the armature core and back to the
beginning of the secondary winding. As in the low-tension armature
type of magneto, there are two sparks produced per revolution of the
armature. The distributor is, therefore, similar to that found on the
low-tension magneto and is driven at similar speeds. The only difference
is that the secondary current is received direct from the armature instead
of being brought back to the distributor from a transformer coil. The
distributor has as many segments as there are engine cylinders and is
driven at one-half the speed of the crankshaft. For a four-cylinder engine
the distributor has four segments and is driven at one-half the speed of the
armature. For a six-cylinder engine there are six segments, and the
distributor arm is driven at one-third the speed of the armature.
The relations of magneto speeds to engine speeds are also the same
as for the armature type of low-tension magnetos. For a four-cylinder
four-stroke engine the armature revolves at crankshaft speed. For
a six-cylinder four-stroke engine the armature revolves at one and
one-half times crankshaft speed. Likewise, for an eight- or twelve-
cylinder engine a magneto of this type must be driven at twice or three
times crankshaft speed, respectively, in order to produce the required
number of sparks per revolution of the engine.
Care should be taken in assembling the magneto to get the distributor
gear timed correctly with the armature so that the distributor brush will
be in proper alignment with the distributor head segment when the inter-
rupter points open with the breaker housing in either the advance or
retard positions. On full advance position the distributor brush should
be moving on to the distributor head segment when the interrupter
contacts open, and should be leaving the same segment when the contacts
open with breaker housing shifted to full retard position. Figure 259
Bhows the punch markings on the distributor gears for the purpose of
timing the distributor with the armature. For a magneto having clock-
wise direction of rotation, the punch mark C on the distributor gear
should mesh with the punch mark on the armature gear, while in the
case of a magneto with anti-clockwise rotation, the gears should be
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THE GASOLINE AUTOMOBILE
meshed so that punch mark A will mesh with the punch mark on the
armature. The direction of armature rotation is usually indicated by
an arrow stamped on the magneto housing near the driving end of the
armature shaft.
The Safety Spark Gap. — In order to protect the insulation of the
armature and of the current-conducting parts against excessive voltage,
a safety spark gap of about *Ke in- is provided as shown in Fig. 256. The
current will pass through this gap in case a cable connection to one of the
spark plugs becomes disconnected while the magneto is in operation, or
if the electrodes on the spark plugs are too far apart. The secondary
OIL WELL COVER
SET SCREW FOR
DISTRIBUTOR
6EAR SHAFT
DISTRIBUTOR BLOCK
SPRING CATCH
REFERENCE POINTS FOR
CHANGING ROTATION
AND TIMING
OIL GROOVE
FOR BALL BEARING
FOR SCREWS TO
ATTACH INTEHRUPPTER"
END PLATE COVER
CONTAINING BALL RACE
ISTRIBUTOR BRUSH
'RUSH HOLDER
DISTRIBUTOR BLOCK
SPRING CATCH
DISTRIBUTOR END OF PENCIL
BRUSH OR CONDUCTING BAR
DISTRIBUTOR 6EAR
DISTRIBUTOR PINION
BALL BEARING
KEY WAY TO
RECEIVE KEY OF
INTERRUPTER
INTERRUPTER END PLATE OIL OVERFLOW
Fig. 259. — Bosch distributor gears showing markings for timing distributor with armature.
current should not be permitted to jump the safety gap for any length of
time, as the continued discharge of the current over the safety gap is liable
to damage the magneto winding and condenser.
The Magneto Grounding Suritch.-^In order to cut off the ignition
without damaging the windings, the primary current must be short-
circuited so that it will not be interrupted when the interrupter points
open. This is arranged for by connecting a wire from the insulated
terminal on the breaker cover, to a simple ground switch which has two
terminals, one of which connects to the engine or chassis frame. The
terminal on the breaker cover is connected by a brush to the insulated
half of the interrupter, so that when the switch is closed, the primary
current is short-circuited through the switch and ground and the magneto
ceases to generate sufficient voltage in the secondary winding to jump
the spark plug points, thus preventing ignition.
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MAGNETOS AND MAGNETO IGNITION
215
178. The Bosch High-tension Dual System. — In the Bosch high-
tension dual ignition system, the standard type of Bosch magneto is used
with the application of two timers or interrupters. The parts of the
regular current interrupter are carried on a disc that is attached to the
armature and revolve with it, the rollers or segments that serve as cams
being supported on the interrupter housing. In addition, the magneto
is provided with a steel cam which is built into the interrupter disc and
has two projections. This cam acts on a lever supported by the interrup-
ter housing, the lever being connected in the battery circuit so that it
-Hi&M TENSION CONNECTION
v BOSCH
NTERHUPTCR COVER
Fig. 260. — Bosch dual magneto showing magneto interrupter and battery timer.
serves as a timer to control the flow of battery current. These parts
may be seen in Fig. 260. A non-vibrating transformer coil is used with
the battery current to produce the necessary voltage.
It is obvious that the sparking current from the battery and from the
magneto cannot be led to the spark plugs at the same time, so a further
change from the magneto of the independent form is found in the removal
of the direct connection between the collecting ring and the distributor.
The collecting ring brush shown in Fig. 261 as No. 3 is connected to the
switch, and a second wire leads from the switch to the central terminal
on the distributor. When running on the magneto, the sparking current
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THE GASOLINE AUTOMOBILE
that is induced in the secondary armature winding flows to the distributor
by way of the switch contacts. When running on the battery, the primary
circuit of the magneto is grounded, and there is, therefore, no production
of sparking current by the magneto; it is, then, the sparking current from
the coil that flows to the central distributor connection. It will thus be
seen that the only parts of the magneto and battery circuits used in
common are the distributor and the spark plugs.
The Bosch Dual Coil. — The Bosch dual coil used in the dual system
consists of a cylindrical housing bearing a brass casting, the flange of
which serves to attach the coil to a dashboard or other part. The coil is
provided with a key and lock, by which the switch may be locked when
Fig. 261. — Wiring diagram for Bosch dual ignition system.
in the "off" position. This is a point of great advantage, as it makes it
unlikely that the switch will be left thrown to the battery position when
the engine is brought to a stop. The absence of such an attachment is
responsible in a large measure for the accidental running down of the
battery. This locking device also prevents the unauthorized operation
of the engine. The parts of the coil are shown in Fig. 262. In addition
to the housing and end plate, they consist of the coil itself, the stationary
switch plate, and the connection protector.
When the engine is running on battery ignition, a single contact
spark is secured at the instant when the battery interrupter breaks its
circuit, and the intensity of this spark permits efficient operation of the-
engine on the battery system.
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MAGNETOS AND MAGNETO IGNITION
217
Starting on the Spark. — For the purpose of starting on the spark, a
vibrator may be cut into the coil circuits by turning the button that is
seen on the coil body in Figs. 261 and 262. Normally, this vibrator is
out of circuit, but the turning of the button places it in the battery
primary circuit. A vibrator spark of high frequency is thus produced.
It will be found that the distributor on the magneto is then in such
a position that this vibrator spark is produced at the spark plug of the
cylinder that is performing the power stroke. If a combustible mixture
is present in this cylinder, ignition will result and the engine will start.
Connections. — In the wiring diagram of this system, as shown in Fig.
261, it will be noted that while the independent magneto requires but one
switch wire in addition to the cables between the distributor and spark
plugs, the dual system requires four connections between the magneto
Fiq. 262.— Parts of Bosch dual coil.
and the switch; two of these are high tension and consist of wire No. 3
by which the high-tension current from the magneto is led to the switch
contact, and wire No. 4 by which the high-tension current from either
magneto or coil goes to the distributor. Wire No. 1 is low tension, and
conducts the battery current from the primary winding of the coil to the
battery interrupter. Low-tension "wire No. 2 is the grounding wire by
which the primary circuit of the magneto is grounded when the switch is
thrown to the "Off" or to the "Battery" position. Wire No. 5 leads
from the negative terminal of the battery to the coil, and the positive
terminal of the battery is grounded by wire No. 7; a second ground wire
No. 6 is connected to the coil terminal.
179. The Bosch High-tension Magneto, Type NU4. — The Bosch
magneto, type NU4, Fig. 263, is of the high-tension, armature wound
type and is suitable only for four-cylinder, four-cycle engines of the
automobile type, rated at or under 30 horse power. A distinct feature of
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THE GASOLINE AUTOMOBILE
this magneto is the absence of the usual gear-driven distributor, this
being incorporated in the form of a double high-tension slip ring mounted
on one end of the armature shaft as shown in Fig. 264. The magneto
interrupter, Fig. 265, is the same as that used in the ordinary Bosch
independent high-tension magneto.
Fig. 263. FiQ. 264,
Fio. 263. — Bosch high-tension magneto, Type NU4.
Fio. 264. — Distributor on Bosch "NU4" magneto showing position of the carbon
brushes with relation to the slip ring.
A circuit diagram of this magneto is shown in Fig. 266. It will be
noted that the circuit of the primary winding is the same as for the Bosch
DU4 shown in Fig. 256. The secondary winding, however, is not con-
nected to the primary, its two ends being connected to the two metal
segments in the slip ring mounted on the armature just inside of the
265.— Interrupter end of Bosch "NU4" magneto.
driving shaft end plate of the magneto. The slip ring has two grooves,
each containing one of the two metal segments. These segments are
set diametrically opposite on the armature shaft, that is, 180° apart, and
insulated from each other as well as from the armature core and magneto
frame.
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MAGNETOS AND MAGNETO IGNITION
219
The four slip ring brushes which collect the secondary current are
supported by two double brush holders, one on each side of the driving
shaft end plate, each holder carrying two brushes arranged so that each
brush bears against the slip ring in a separate groove. Upon rotation
of the armature, the metal segment in one slip ring groove makes contact
with a brush on one side of the magneto at the same instant that the
metal segment in the other slip ring groove comes into contact with a
brush on the opposite side of the magneto. The marks "1" and "2"
appearing in white on both brush holders indicate pairs of brushes receiv-
3PARK PLUGS
- — MAGNETS
PLATINUM INTERRUPTER
POINTS SHOULD OPEN aiTOO*'
INSULATED INTERRUPTER
CONTACT
STEEL CAM
Fig.
MAGNETO GR0UNDIN6\£f©Y ,7*"^1NTERRUPTER COVER
TERMINAL
266. — Circuit diagram of Bosch "NU4" high-tension magneto.
ing simultaneous contact, those marked "1" constituting one pair, and
those marked "2," the other.
From the wiring diagram it is important to note that as two of the
four slip ring brushes make contact simultaneously and each is connected
by cable to the spark plug in one of the cylinders, the secondary circuit
always includes two plugs, and the spark occurs in two cylinders at the
same time, namely, cylinders Nos. 1 and 4 or 2 and 3. Only one of these
sparks, if properly timed, will cause ignition, since in a four-cylinder
engine, when No. 1 cylinder is under compression ready for ignition, No. 4
piston is finishing its exhaust stroke and the cylinder contains nothing
but burned exhaust gases. The same relation exists when each cylinder is
ready for ignition, the other cylinder in which the spark occurs containing
non-combustible exhaust gases. Care should be taken in timing this
type of magneto so that when fully retarded the spark will not occur in
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220
THE GASOLINE AUTOMOBILE
the dead cylinder after the intake valve has opened, which is usually a
crank angle of about 8° to 10° past upper dead center. The platinum
interrupter points should be adjusted to open 0.015 in. while the spark
plugs should be adjusted to a gap of .020 to .030 in., or the thickness of a
worn dime.
180. The Eisemann High-tension Magneto, Type G4. — The Eise-
mann high-tension magneto, type G4, Fig. 267, is typical of the various
models of the Eisemann magneto. It is made in two types known as
G4, I Edition, and G4, II Edition. The principal differences between
the two models are in the design of the interrupter mechanism and in the
construction of the armature housing.
In the type G4, 1 Edition, shown in Fig. 268, the movable contact of
the interrupter is carried on a flat spring instead of on the usual rocking
type lever. The interrupter points are actuated by this spring striking
the two fiber cams on either side of the center part of the timing lever
Fiq. 267. — Eisemann high-tension magneto, Type G4 — II Edition.
body. The fixed end of the spring is grounded to the magneto frame
through a grounding brush which bears on the inside of the timing lever
body. In this type of magneto the interrupter platinum points may be
adjusted without removing the timer body, as shown in Fig. 269. In
the type G4, II Edition, the usual form of rocking type interrupter is
used, in which the interrupter lever is actuated by two steel segments
or cams mounted on the inside of the timing lever body, as shown in
Fig. 270. The platinum contacts in both types of magnetos should be
adjusted to open .13 to .17 in.
The armature housing or frame of the type G4, II Edition, consists of
the unit-cast construction shown in Fig. 271, whereas the I Edition hous-
ing is built up of several parts screwed together. This unit-casting is
extremely rigid, thus positively eliminating all danger of loosened screws
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MAGNETOS AND MAGNETO IGNITION
221
DISTRIBUTOR PLATE
CABLE FOR CUTTING
OFF IGNITION
DISTRIBUTOR
CARBONS
END CAP
- SETTING SCREW
DISTRIBUTOR DISC (SETTING MARKS
CARBON BRUSH PICKING UP X
CURRENT FROM COLLECTOR RING
FIBRE
CAMS
TIMING LEVER
BODY
COPPER BRUSH FOR SHORT
CIRCUITING IGNITION
Ito. 268. — Principal parts of Eisemann high-tension magneto, Type G4 — I Edition.
ft®. 269.
— Eisemann magneto, Type G4 — I Edition, with distributor removed showing
setting marks for timing, also method of adjusting interrupter contacts.
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222
THE GASOLINE AUTOMOBILE
or end plates, due to vibration or accidental twisting. Another advan-
tage of the unit-casting is the absence of any joints. Consequently, an
absolutely water-, oil-, and dust-tight protection is provided for the vital
elements, such as the winding and the condenser. The unit-casting can
be bored out and machined all in one piece, and also because of its rigidity,
it is possible to better maintain the running clearance between the arma-
ture and the poles of the magnets. This tends to give increased magnetic
efficiency, and, as a result, a much hotter spark.
The Armature. — The armature used in the Eisemann magneto is shown
in Fig. 272.- The armature which carries the winding is of the H- shaped
•istrirrtor rim
RITH
UTEI-riOOr CARLE HSTEHIROS
irdicator rout
fOI SCTTIRQ MAORETt
TO MOTOI
SCTTIPIO
JUIKS
•ATM r.vivir ERR
CAR fOt BICAKCR
«A0ft£fO CRIIKf
■If MER MINT*
IMIH6 lit ER RMf
Fig. 270. — Principal parts of Eisemann high-tension magneto, Type G4 — II Edition.
type, similar to that shown in Fig. 251. On this core are wound a few
layers of medium-sized copper wire, the beginning end of which is grounded
to the armature core. The other end of the wire is connected through
the interrupter fastening screw to the insulated contact of the breaker
mechanism. Over this primary winding is the secondary winding con-
sisting of many turns of very fine copper wire, the wire itself being in-
sulated its entire length and the layers carefully insulated from each
other. A circuit diagram of the Eisemann, type G4, I Edition, is shown
in Fig. 273. It will be noted that the beginning of the secondary is
connected directly to the end of the primary winding and the end is led
to the collector ring which is mounted on the same end of the armature
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MAGNETOS AND MAGNETO IGNITION
223
as the interrupter. The condenser, which is connected so as to protect
the interrupter points, is mounted in the other end of the armature.
Pole Pieces. — One of the distinct features of the Eisemann magneto
is the shape of the pole pieces, which are wedge-shaped as shown in Fig.
274. These wedge-shaped pole pieces cause the magnetic lines of force
Fig. 271. — Frame casting for Eisemann magneto, Type G4 — II Edition.
to flow from the extremities of the pole pieces toward the center of the
core. All of the magnetic lines of force are thus forced through the wind-
ing of the armature and are not diffused as in the case of the straight pole
pieces which are most commonly used. The wedge-shaped pole pieces
also prolong the duration of maximum current in the primary winding,
CONDENSER
ARMATURE
WINDING
COLLECTOR RING
Fiq 272. — Armature for Eisemann magneto.
when the corner of the armature passes the pole pieces, thus increasing
the angle of spark range and permitting a hotter spark with breaker in
retard position. The armature which is always overlapped by the pole
pieces acts as a keeper to the magnets, thereby aiding in preventing de-
magnetization which is common to magnetos with straight pole pieces.
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224
THE GASOLINE AUTOMOBILE
These pole pieces greatly reduce the wear on the coupling or gear which
drives the magneto, by preventing the sudden breaking of the magnetic
field. This feature also aids in making the magneto gears noiseless.
TO SPARK PLUGS
DISTRIBUTOR
PLATE
HI6H TENSION
COLLECTOR BRUSH
RUSH IN END PLATE'
PRIMARY
.SECONDARY
MAGNETO GROUNDS*
SWITCH
CONDENSER SAFETY '©AjP ~~ INTERRUPTER
(BETWEEN NT. 8UPRUM 4R0UN0 BRUSH
ANO SCREW IN END HOUSING
TIMING LEVER
TACT ARH ACTUATED
BY PIBtR CAMS I
LEVER HOUSIN*
Fig. 273. — Circuit diagram of Eiaemann high-tension magneto, Type G4 — I Edition.
The Distributor. — By placing the collector ring on the same end of
the magneto as the distributor head, the necessity of carrying the high-
tension current around the magneto by means of brushes and conductors
FiG. 274. — Diagram showing the wedges-haped pole pieces used on Eisemann magnetos.
is done away with. Instead, a brush in the distributor plate, carried
straight down to a contact with the collector ring, is used and in this
manner the high-tension current is carried directly to the center brush in
the distributor plate. This center brush in turn makes contact with the
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MAGNETOS AND MAGNETO IGNITION
225
metal insert of the distributor disc. This disc is attached to the distribu-
tor gear and, consequently, rotates with it, so that the metal insert
makes contact in rotation with each of the outside carbons of the distribu-
tor plate, whence the current is led to the spark plugs by the high-
tension cables.
The safety spark gap is located in the breaker end of the magneto
instead of in the arch of the magnets, as in the usual armature wound type
magneto. It consists of a gap of about JKe *n- between the collector ring
and the point of a screw placed in the armature housing, immediately
behind the breaker. Its purpose is to provide a by-pass for the high-
tension current in case a spark-plug cable should become disconnected or
broken, thereby protecting the winding and other high-tension insulation
against possible injury.
181. The Eisemann High-tension Dual Magneto, Type GR4. — The
Eisemann high-tension dual magneto, known as type GR4, II Edition,
is shown in Figs. 275 and 276. It is
used in conjunction with a battery
(either dry cells or storage battery)
and either the DC or the DCR type
coil shown in Fig. 277.
The primary purpose of this sys-
tem is to give two sources of ignition
(magneto and battery) using one dis-
tributor and one set of spark plugs.
The arrangement consists essentially
of a direct high-tension magneto,
used in conjunction with a combined
transformer coil and switch which
can be mounted on the dash. This
transformer coil is used only in connection with the battery, whereas the
switch is used in common with both the battery and the magneto.
The magneto, as may be seen from Fig. 276, is practically the same as
the type G4 independent magneto with two exceptions, the timing arm
is equipped with an extra separate contact breaker for the battery current,
and the distributor is modified to permit of its electrical separation from
the magneto armature, when distributing the battery high-tension
current.
This magneto may be used with equally good results with either of the
Eisemann dash coils, type DC or type DCR, Fig. 277. The coils
differ only in the arrangement for starting on the spark, the DC having
a push-button giving a single spark, provided the engine happens to
stand with the battery breaker open; whereas the DCR has a mechan-
Fio. 275. — Eisemann high-tension
dual magneto, Type GR4 — II Edition.
15
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226
THE GASOLINE AUTOMOBILE
DISTRIRUTOR PLATE
llfH
■ATER-PROOF CARLE FASTENINGS
INDICATOR' POINT
FOB SETTIHO NARRETO
TO NOIOR
SETTING
MASKS
DISTRIBUTOR
CAABON BRUSHES
CARBOH BRUSl
TO PICK UP CURRENT
f ROM COLLECTOR NINO
CABLE CONNECTION
FOR CUTTING OFF MAONETO
IGNITION
1ATER-PROOF END
CAP FOB BREAKERS
BINDINQ POST
FOR BATTERY
BREAKER
■ATERPR0OF RBI
FOR BATTERY
BIRDINO POST
TIMING LEVER BODY
MAONETO CONTACT
BREAKER POINTS
Fio. 276. — Principal parts of Eisemann high-tension dual magneto, Type GR4 — II
Edition.
Type " D.C.R." coil. Type " D.C." coil."
Fia. 277. — Dash coil and switch units for Eisemann high-tension dual magneto, Type
GR4.
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MAGNETOS AND MAGNETO IGNITION
227
ical ratchet device, delivering a shower of sparks regardless of the crank
position of the engine.
A rapid back and forth motion of the starting handle on the front of
the DCR coil causes the toothed ratchet in the center to oscillate the
lever B, Fig. 278, which, in turn, makes contact alternately at C and
D. If the switch is on battery position and the battery breaker
points in the magneto are closed, as they normally are, a rapid sequence
of sparks will occur at the plugs. This shower of sparks is much more
effective for starting on compression than a single spark.
A circuit diagram of the system, including the coil connections for the
different switch positions, is shown in Fig. 279. As may be seen, the
battery breaker operates in much
the same manner as the corre-
sponding part on the magneto. It
is actuated mechanically by two
polished steel cams attached to
the magneto breaker, but is en-
tirely separate, electrically, from
it. Like the magneto breaker, the
battery breaker causes the spark
to occur at the instant of separa-
tion of the contact points. For
practical reasons, this interruption
is timed to take place 10 degrees
later than the magneto, but is,
naturally, subject to the same de-
gree of advance and retard, being
mounted in the same timing lever
body. Both breakers are pro-
tected by the same waterproof cap, and are easily exposed to view.
Both sets of contact points should be adjusted to open from .012 in.
to .014 in. The distributor is the same as the G4 except that there is
no connection between the lower carbon (collector) brush and the center
one. Cables lead from each of these brushes to the switch portion of
the coil, enabling the center brush to be connected to the lower one when
running on the magneto, or to the coil when running on the battery.
If for any reason it is desired to operate the magneto without the
coil and switch unit, it may be operated as an independent high-tension
magneto, the same as the type G4, by connecting the cables marked
H and KM on the distributor head, thus making a direct path for the
high-tension current from the collector ring to the distributor.
182. Timing of the Eisemann Magneto to the Engine for Variable
Spark. — As the spark occurs when the primary circuit is broken by the
Fio. 278.— Type "DCR" coil with front
plate removed showing mechanism for start-
ing on the spark.
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228
THE GASOLINE AUTOMOBILE
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MAGNETOS AND MAGNETO IGNITION 229
opening of the platinum contacts on the breaker mechanism, it is neces-
sary that the magneto be so timed that at full retard position of the timing
lever body the platinum contacts just begin to open when the respective
piston of the engine has reached its highest point on the compression
stroke. The engine should be turned by hand until piston of No. 1
cylinder is on dead center (firing point). The distributor plate should
then be removed from the magneto and the driving shaft turned until
the setting mark on the distributor disc is in line with the setting screw
as shown in Figs. 268, 270, and 276. (For a magneto rotating clockwise,
setting mark R is used, and for anti-clockwise setting mark L is
used.) With the armature in this position and the timing lever body
fully retarded, the platinum contacts of the magneto breaker are just
opening, and the metal insert of the distri-
butor disc is in connection with the car-
bon distributor brush for No. 1 cylinder.
The driving medium must now be fixed
to the armature shaft without disturbing
the position of the latter, and the cables
connected to the plugs in their proper
order of firing.
It has been found advisable in prac-
tice to time the battery spark slightly
later than that of the magneto itself.
For this reason the battery breaker on
the Eisemann dual type magneto is per-
manently arranged to open 10° later than Fio. 280.— The Dixie high-tension
the magneto breaker, although subject to magneto, Model 46.
the same degree of advance and retard.
183. The Dixie Magneto. — The Dixie high-tension magneto, Fig. 280,
differs widely from the usual armature wound type in that the winding
does not rotate. In this respect it is virtually an inductor type magneto,
operating on what is known as the " Mason Principle." The construction
and general arrangement of the various parts are shown in Fig. 281,
which is a front view with the distributor block and breaker cover re-
moved ; and in Fig. 282 which is a side view with the cover and one magnet
withdrawn. The magnets and rotating element are shown- in Fig. 283.
It will be noted that the magneto consists principally of a pair of
magnets, a rotor, a field structure, a winding, an interrupter, and a con-
denser. The rotor, Fig. 284, consists of two revolving wings, N and
S9 separated by a bronze center piece, B. The ends of the wings are
brought into contact with the poles of the magnets as shown in Fig.
283, and, therefore, bear the same polarity of magnetism as the poles of
the magnets with which they are in contact. This polarity of the wings
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230
THE GASOLINE AUTOMOBILE
is always the same, as there is no reversal of magnetism through them.
The rotor is surrounded by a field structure which carries laminated pole
extensions, on which the winding with its laminated core is mounted.
The grinding contains both primary and secondary windings. As the
rotor revolves, it causes the magnetic flux to flow back and forth through
the core of the winding, first in one direction and then in the other,
according to the position of the rotor in relation to the poles of the field
structure as shown in Figs. 285, 286, 287, and 288. Figure 286 shows the
9. Ground spring.
10. Thumb nut for ground stud.
11. Lock washer for ground stud nut.
12. Washer for ground stud.
13. Cam.
14. Distributor block.
15. Thumb nut for distributor block.
16. Breaker base.
17. Breaker bar spring.
Front view of Dixie magneto with distributor head and breaker dover
removed.
1. Distributor gear.
2. Distributor disc.
3. Finger spring for breaker bar.
4. Cam screw.
5. Breaker bar with platinum point.
6. Contact screw bracket with insu-
lating bushings.
7. Platinum contact screw.
8. Breaker cover.
Fig. 281
rotor in such a position that the flux flows from wing N through
the core C and back to wing S of the rotor. Figure 288 shows the
flux flowing in the reverse direction.
The greatest intensity in the primary circuit occurs when the rate of
change of the flux or magnetic lines of force through the core is a maxi-
mum. This occurs when the rotor is in the position shown in Fig. 287,
where the rotor wings have just reversed the direction of flux through
the core, the gap between the trailing wing corner and pole piece being
from .015 in. to .035 in., preferably .020 in. Consequently, the inter-
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MAGNETOS AND MAGNETO IGNITION
231
rupter contact points should be adj usted to break the primary circuit when
the rotor is in this position. A circuit diagram of the magneto is shown
in Fig. 289 from which it will be seen that the primary circuit is of the
interrupted primary current type. The breaking of the primary circuit
induces a high-voltage current in the secondary winding, this current
1. Condenser.
2. Magnet.
3. Gap protector.
4. Oil hole cover, front.
5. Stud for distributor block.
6. Clamp for distributor block.
7. Thumb nut for distributor block.
8. Hexagonal nut for grounding stud.
9. Thumb nut for grounding stud.
10. Grounding stud.
11. 8ereir and washer for fastening breaker.
12. Screw and washer for fastening condenser and
primary lead to winding.
13. Screw and washer for fastening primary lead
tube clamp.
14. Primary lead tube.
15. Primary lead tube clamp.
16. Screw and washer for fastening grounded clip
to pole structure.
17. Rotor shaft.
18. Drive key.
19. Back plate.
20. Oil hole cover, back.
21. Grounding clip.
22. Screw and washer for fastening grounding clip
to winding.
23. Winding.
24. Screw and washer for fastening winding to
pole structure.
Fio. 282. — Side view of Dixie magneto with cover and one magnet removed.
being directed to the proper plug by a distributor driven by a gear on the
rotor shaft. The condenser, one terminal of which is connected to the
insulated end of the primary coil and the other grounded to the magneto
frame, is mounted on the top of the coil.
One of the outstanding features of the Dixie magneto is the shifting
of the pole pieces with the timing lever, upon advancing and retarding
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232
THE GASOLINE AUTOMOBILE
Fio. 283. — Rotor and magneto for
Dixie magneto.
the spark. This permits the breaker to interrupt the primary circuit at
all times when the primary current is flowing at its maximum, thus
causing a spark of maximum intensity at all positions of the breaker.
Since the coil windings are not on a revolving armature, the interrupter
is built like that for a low-tension magneto, that is, the interrupter
mechanism is mounted on the interrupter housing and the cam is revolved
with the rotor shaft. This construction permits the adjusting of the
contact points with the engine and
magneto running. The contacts are
made of platinum and should be ad-
justed to open .020 in. This adjust-
ment can be made with a screwdriver
by turning the stationary contact
screw.
Magneto Switch. — Extending
through the magneto breaker cover
is an insulated terminal which is con-
nected to the insulated end of the
magneto primary winding. This ter-
minal is also connected to a grounding
switch by which the primary winding
can be grounded or short-circuited, and ignition prevented. The Dixie
magneto switch is shown in Fig. 290. The wire leading from the mag-
neto must be attached to one of the terminals on the back of the switch
and the other terminal grounded. The ignition is locked when the switch
lever is in the "off " position. When in this position the switch lever can
be taken out, preventing the operation of the magneto.
Timing. — The method of tim-
ing the Dixie magneto with the
engine is similar to the timing
of other types of high-tension
magnetos. The crank of the en-
gine should be turned until one
of the pistons, preferably that of
cylinder No. 1, is on upper dead-center position at the end of the com-
pression stroke. With the timing lever in full retard position, the
driving shaft of the magneto should be rotated in the direction in which
it will be driven. The circuit breaker should be closely observed, and,
when the platinum contact points are about to separate, the drive gear
or coupling should be secured to the drive shaft of the magneto. Care
should be taken that the position of the magneto shaft is not altered when
the nut is tightened to secure the gear or coupling. After this is done,
the magneto should be secured to its base. The distributor block should
2
E
01
O
Fig. 284. — Rotating element in Dixie
magneto.
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MAGNETOS AND MAGNETO IGNITION
233
then be removed to determine which terminal of the block is in contact
-with the bronze sector of the distributor disc. The terminal found in
contact should be wired to the cable leading to No. 1 cylinder, and the
^\
im
rt=Ms
s
Fig. 285. Fig. 286. Fig. 287. Fio. 288.
Figs. 285 to 288. — Showing the principle of the Dixie magneto.
remaining cables to the remaining cylinders in accordance to their
sequence of firing, remembering that the distributor runs the opposite
direction from the rotor of the magneto.
MAGNETS
TO SPARK PLUGS
A 1
SECONDARY
PRIMARY \V
COIL-
DISTRIBUTOR
BLOCK
BRASS HIGH-
TENSION 3EGMENT
ON COIL
ROTOR
BREAKER BASE
TIMER L£VER
" MAGNETO GROUNDING
-J? CAM TERMINAL ( INSUL ATED)
GR-
GROUND -^
MAGNETO GROUNDING
SWITCH
Fig. 289. — Circuit diagram of Dixie high-tension magneto, Model 46.
184. General Instruction for High-tension Magneto Care and Main-
tenance.— To insure proper working of the magneto, periodic inspection
and attention are very essential.
Oiling. — A few drops of light, clean, high-grade oil should be injected
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234
THE GASOLINE AUTOMOBILE
into every oil hole each 1000 miles of travel. Too much oil should not
be used.
Distributor Block. — The distributor block should be removed every
2000 miles and- cloaned so as to remove any carbon deposit caused by
the wearing of the brushes. This may be done with a soft cloth moistened
with gasoline. The gasoline should be allowed to dry up thoroughly
before the engine is started. The same attention should be given the
high-tension slip ring on the armature. The distributor and slip ring
brushes should be inspected to make sure that they are not stuck in
their holders and that the springs have the proper tension.
Interrupter. — The contact points of the interrupter should be exam-
ined every 1000 to 1500 miles to see that they are clean and have the
right point opening. If they are dirty or badly pitted and uneven they
should be cleaned by passing a thin fine file or
a piece of No. 00 sandpaper between them.
The contacts must not be filed unless absolutely
necessary. The contacts should make square
contact across their entire contact surface.
The contact points have a standard open-
ing of .012 to .020 in. Usually an adjust-
ing wrench, which has a gauge to measure
the proper point opening, is furnished with
the magneto.
A slight trace of clean oil or grease put on
the fiber block of the interrupter lever, or on
the steel cam, every 1000 to 1500 miles, will
prevent the cam from rusting. The contact
points must never be oiled.
Wiring. — The wiring should be examined
carefully at least once each year. If cables are cracked or worn, they
should be replaced. All connections must be kept clean and tight.
Spark Plugs. — Failure of ignition is usually due to dirty spark plugs.
When the engine does not fire regularly, the plugs should be examined,
and if found to be sooted they should be cleaned by scraping off the
carbon and washing them in gasoline. The opening of the plug gap
should measure .025 to .030 in. After the plugs have been replaced
in the cylinders, they should be examined to make sure that none of the
porcelains have cracked.
Testing the Magneto. — If the engine fires irregularly, indicating poor
ignition, the magneto may be tested by resting a screwdriver on the
magneto housing and holding it about % to % in. from the high-tension
collector ring or collector ring brush terminal. If upon rotating the
armature, a spark jumps across the gap, it shows that the trouble does
^^^^"n t^ ■»■ l^^B
""i
1
YO MAGNETO JJ
V
0»)
Mb h3
|
Fig. 290. — Dixie magneto
switch.
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MAGNETOS AND MAGNETO IGNITION 235
not lie in the magneto, but in some other part of the engine, possibly
the carburetor or gasoline system.
Magnets. — A remagnetization of the magnets will be. necessary only
when they have been taken away from the magneto and* allowed to remain
a long time without the ends being connected with a piece of soft iron
known as a keeper. Demagnetization of the magnets will also occur if the
armature is taken out from between the pole pieces without a conducting
bar of iron being first laid across both poles. This conducting bar
should be placed on the poles before the armature is entirely removed
and should remain until the armature is again placed between the pole
pieces. The magnets, after being taken down, are often put back in the
wrong position and in this way the magnetic power is neutralized. To
prevent this mistake the magnets are usually marked, the North pole
being designated by the letter N stamped in the magnet. When replac-
ing magnets, care should be taken to place the like poles on the same
side.
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CHAPTER IX
THE AUTOMOBILE STORAGE BATTERY
186. Function of the Battery. — The storage battery on the automobile
may be considered the heart of the entire electrical system. Its function
may be compared to that of the storage tank or reservoir in the typical
waterworks system of the modern small town. The reservoir corresponds
to the storage battery, the pump to the generator, and the water mains
to the wiring of the car. When the generator produces more current
than is consumed by the ignition, lamps, or other electrical accessories,
the surplus current passes through the battery, causing it to take on an
electrical charge, that is, to store up energy as ordinarily understood.
When the engine is at a standstill and the generator is not running, or if
the engine is not driving the generator
fast enough to produce the required
amount of current, the battery supply
may be drawn upon for cranking the
engine, operating the lights, supplying
ignition, operating the horn, or perform-
ing any other service for which the
electrical system may be designed.
The cause of most battery troubles
is due to improper care of the battery
and misuse of the electrical equipment
on the part of the user, chiefly because
he does not understand the principles
involved. It is, therefore, the purpose of
this chapter to remove, as far as possible, the mystery surrounding the
storage battery and to explain its construction, operation, care, and
troubles in as clear and concise a manner as possible.
186. Construction. — The storage battery, Fig. 291, as used for
starting, lighting, and ignition purposes consists of three or more cells,
depending upon the voltage desired. Each cell has an electric pressure
of about two volts. A battery of three cells connected in series is known
as a 6-t>oft battery and one of six cells in series is known as a 12-twft
battery. Each cell consists of a hard rubber jar in which is placed two
kinds of lead plates known as positive and negative. These plates are
insulated from each other by suitable separators and are submerged in a
237
Fio. 291. — 6-volt automobile
storage battery.
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238
THE GASOLINE AUTOMOBILE
solution of sulphuric acid and water. Typical cell construction is shown
in Figs. 292 and 151.
187. The Plates. — The grid, or framework of the plate, is cast from
an alloy of lead and antimony and is similar in appearance to a coarse
wire netting or filigree work as shown in Fig. 293. ' The open spaces
Fig. 292. — Construction and internal arrangement of typical storage battery cell.
are pressed full of a putty-like paste or compound known as active mate-
rial consisting chiefly of oxides of lead. When dry, this active material
becomes hard like cement. The plates are then put through an electro-
chemical process which converts the active material of the positive plates
into brown peroxide of lead, Fig. 294, and that of the negative plates
into a grey spongy metallic lead as
in Fig. 295. This process is known
as forming the plates.
188. Positive and Negative
Groups. — Af ter the positive and nega-
tive plates have been formed, they
are built into positive or negative
groups as in Fig. 296. The positive
group consists of one or more positive
plates burned to a connecting strap,
and the negative group of two or
more negative plates connected to a
similar connecting strap. To each
strap is attached a post which is used to make electrical connection
between two adjoining groups or to the starting and lighting system.
189. Elements. — An element, as shown in Fig. 297, consists of a posi-
tive and a negative group, together with the separators. The negative
group always has one more plate than the positive group as shown in
Fig. 298. For example, a three-plate element would have one positive
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Fio. 293. — Types of battery plate grids.
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THE AUTOMOBILE STORAGE BATTERY
239
and two negative plates and a five-plate element would have two
positive and three negative plates. This is true regardless of the
number of plates in the element.
The plates are burned to the connecting straps, usually by a hydrogen
or oxy-acetylene flame, so that the plates and strap form one unit. The
Fio. 294. — Positive plate.
Fio. 295. — Negative plate.
plates are so arranged that when the element is assembled, each positive
plate surface is adjacent to a negative plate surface, the distance between
these surfaces being from % 2 to % in. The positive and negative sur-
faces are kept apart by insulators known as separators.
190. Separators. — The separators play a very important part in the
life and operation of the battery, since they insulate the positive and
Fio. 296.— Battery group.
Fio. 297.— Battery element.
negative plates from each other and prevent short circuits between them.
If the separators become cracked, or damaged in any other way, per-
mitting electrical contact between the plates, the battery will discharge
and may ultimately become useless. Two principal kinds of separators
are used, namely, wood and threaded rubber.
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THE GASOLINE AUTOMOBILE
The wood separator, Fig. 299, is made of specially selected wood,
usually basswood or cypress, and is chemically treated to remove the
acetic acid and other impurities which are always in the wood and which
are harmful to the battery. This chemical treatment also makes the
wood porous, and thus allows ready diffusion of the electrolyte through
Fig. 298. — Positive and negative group.
the separator pores upon the charging and discharging of the battery.
The separators are grooved on one side. When the separators are in-
stalled, this grooved side should be placed next to the positive plate
with the grooves running vertical as in Fig. 300. The purpose of these
grooves is to permit the gas which accumulates around the positive plate,
which is the most active plate, to escape
freely to the surface. The grooves
also provide a passageway for any
active material, which may free itself
from the plate, to fall to the sediment
space below.
i
1
H
Fio. 299. — Wood separator.
Fig.
300. — Inserting separators in battery
element.
The threaded rubber separator, Fig. 301, is manufactured by the
Willard Storage Battery Company and is used exclusively on the Willard
battery. From Fig. 302, which shows a magnified view of this separator,
it will be seen that the threads run through the separator at right angles
to the surface. According to the manufacturers, there are 196,000 of
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THE AUTOMOBILE STORAGE BATTERY
241
these threads per square inch. The theory is that each thread acts
as a wick between the positive and negative plates. The separator is
Fro. 301. — Willard threaded rubber separator.
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Fio. 302. — Microscopic section of Willard threaded rubber separator.
thus rendered porous due to the capillary attraction of the threads.
Another feature of this separator is that it does not carbonize and crack
16
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242
THE GASOLINE AUTOMOBILE
upon drying out as does the wood. On this account the life of the sepa-
rator and battery is greatly increased. The threaded rubber separator
has corrugations which correspond to the grooves of the wood separator
and should be installed in a similar manner with the corrugations running
vertical.
191. The Electrolyte. — The electrolyte, as used in all types of auto-
mobile lead storage batteries, consists of a mixture of chemically pure
sulphuric acid (H2S04) and distilled water,
the proportion being about 1 part of acid
to 3 parts of water by volume. The pro-
portion of water and acid is such that the
density of the solution will have a specific
gravity of 1.300 at 70°F.
Specific Gravity. — By specific gravity
is meant the relative weight of any sub-
stance compared with the weight of an
equal volume of pure water. Pure water
has a specific gravity of 1, usually written 1.000 and spoken of as (en
hundred. One pound of water has a volume of approximately one pint.
An equal volume of chemically pure sulphuric acid weighs 1.835 lbs.
It, therefore, has a specific gravity of 1.835 and is spoken of as eighteen
thirty-five.
192. Jars and Covers. — The jars forming the cells, Fig. 303 and Fig.
304, are made of hard rubber, designed to resist both the action of the
Fio. 303.— Rubber jars.
LATES
BRIDGED
SUPPORT
SEDIMENT
SPACE
Fio. 304. — Cut away section of storage cell showing sediment space below the plates.
electrolyte and mechanical strains. Bridged supports, Fig. 304, are
molded in the bottom of each cell to hold the plates and separators off
the bottom thus forming a sediment chamber for catching the accumu-
lation of any active material which may free itself from the plates.
The cover, Fig. 305, is of hard rubber with an opening in the center
for the vent cap and an opening on each side for the connecting posts of
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THE AUTOMOBILE STORAGE BATTERY
243
the positive and negative groups, which are known as terminals. The
cover also provides an expansion chamber for the electrolyte.
193. Cell Arrangement. — A complete cell consists of tl^e rubber jar,
the element in the jar resting on the bridges, the electrolyte covering
the element, and the cover which is carefully
sealed to the jar with sealing compound.
The complete battery consists of the
desired number of cells assembled in a
wooden case, the cells being connected in
accordance with the requirements of the
starting and lighting system with which
the battery is to be used,
trated in Fig. 306.
194L Battery Box. — The battery box is made of hard wood thoroughly
coated with an acid-proof paint. The cells are usually sealed in place
by pouring a sealing pitch-compound over the entire top. This prevents
Fio. 305. — Cover for battery cell.
Some of these various connections are illus-
Fig. 306. — Typical cell arrangements for starting and lighting batteries.
any vibration of the jars and renders the tops of the cells dirt and leak
proof. In some cases, where specially designed covers are used, only the
individual cell tops are sealed. This adds greatly to the ease with which
the battery can be taken apart.
It is absolutely essential that the battery be securely held in position
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244 THE GASOLINE AUTOMOBILE
on the car. For this purpose, brackets which fit on the battery case
are often used. The battery is usually made fast to the car by means
of bolts engaging the hold-down clips.
195. Markings of the Battery. — For convenience in connecting up
the battery, the terminals are ordinarily marked either with Pos (+),
(plus sign) or a red fiber sleeve on the positive post and with Neg or
( — ) (negative sign) on the negative post. This marking is in accordance
with the way the battery discharges, the current leaving the positive
terminal ahd returning to the negative.
It is also customary among battery manufacturers to make the posi-
tive cable connection larger than the negative. If the terminals are not
marked, the polarity can be readily determined by attaching a wire lead
to each terminal and inserting the two free ends in a glass of salt water or
battery electrolyte, whereupon gas bubbles (hydrogen) will be noticed
to form around the negative lead, as in Fig. 307.
POSITIVE LEAD + NEPATtVC L£AD
Gas Dufi5LC3 Around
NeoATivL Terminal
Salt Water or
Cattcry Electrolyte
Fio. 307. — Method of determining polarity of storage battery terminals.
196, Voltage of the Battery. — Each cell, after being properly charged,
gives approximately two volts with a current capacity corresponding to
the size of the plates and the total number of square inches of free active
material in them. Consequently, when several cells are connected in
series, that is, the terminals connected positive to negative, the same
as in connecting dry cells for ignition, the total voltage across the battery
terminals will be the added voltage of all the cells, while the current
capacity will be the same as the current from one cell. For example,
across a 3-cell battery, the voltage is 6 volts and across a 6-cell battery the
voltage is 12 volts. It will be found later that the voltage varies
slightly with the condition of charge and the temperature.
197. Battery Capacity. — The capacity of a battery is measured in
ampere-hours. This is determined by multiplying the number of amperes
by the number of hours during which the battery is capable of discharg-
ing at a given rate. For example, a battery that will deliver 10 amperes
for 10 hours is said to have a capacity of 100 ampere-hours at the 10-
ampere discharge rate. However, one of the inherent characteristics
of a storage battery is that its ampere-hour capacity is dependent upon
the rate of discharge. The lower the rate of discharge the greater the
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THE AUTOMOBILE STORAGE BATTERY 2A5
ampere-hour capacity will be. The same battery that has a capacity
of 100 ampere-hours at the 10-ampere discharge rate will have a capacity
in excess of 100 ampere-hours at a 5-ampere rate, that is, it will deliver
5 amperes for more than 20 hours. On the other hand, the battery would
not discharge 100 amperes for 1 hour since the efficiency of the battery
drops when discharging at a rate higher than that specified by the manu-
facturer. This rating is usually found on the name plate of the battery.
198. Principle of Operation. — When the cell is fully charged the
electrolyte has a density, or specific gravity, of 1.275 to 1.300; the active
material on the positive plates being peroxide of lead and on the negative
plates pure spongy metallic lead. The pressure between the positive and
negative groups is about two volts, and if these groups are connected to-
gether through an electric conductor, such as an electric lamp or a motor,
current will flow between them, discharging the cell. During the dis-
charge a chemical action takes place which converts both the lead per-
oxide on the positive plates and the pure spongy metallic lead on the
negative plates to sulphate of lead. This chemical change removes sul-
phur from the acid, thereby lowering the specific gravity or density of the
solution. When the cell is considered completely discharged its density
is 1.160 or below, and its voltage about 1.8 volts or loss.
When current is sent through the cell in an opposite, or charging,
direction a chemical action occurs, precisely the reverse of that on dis-
charge. The action of the charging current removes the sulphur from
the plates, changing the lead sulphate on the positive plates back to lead
peroxide, and that on the negative plates to pure spongy metallic lead.
Inasmuch as the sulphur returns to the solution, this solution becomes
more dense, and when the cell is fully charged the solution reaches its
original density of 1.275 to 1.300.
199. Effect of Overcharging. — As above stated, the charging current
changes the plates back to their original chemical formation. When the
element is completely charged, the charging current can do no more useful
work; consequently, its only effect is to convert particles of water in the
electrolyte to hydrogen and oxygen gas which bubble up violently and
indicates that the battery is nearing a full state of charge.
200. Effect of Undercharging. — If the element does not receive
sufficient charge, the sulphate may harden to such an extent as to be
very difficult to remove from the plates. Furthermore, if the battery
is allowed to remain in an uncharged condition, a denser and harder
sulphate which is even more difficult to remove will form on the plates.
This hardening of the sulphate takes place to some extent even when
the battery is considered fully charged. It is advisable, therefore,
to charge the battery immediately after a discharge, and about once a
month when idle, even though it be fully charged.
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THE GASOLINE AUTOMOBILE
201. Heat Formed on Charge and Discharge. — When the element is
charged or discharged, the chemical reactions due to the passage of the
current through the electrolyte cause heat to be formed. This heat does
not become injurious until the temperature rises to about 105°F., and
it may rise to 110°F. or even higher for a brief period of time without
injury to the plates. It is not considered advisable, however, to charge
a battery for any length of time after the temperature has risen to 105°F.
The battery should be taken off charge and allowed to cool or the charg-
ing rate reduced.
202. Evaporation of Water. — The water in the electrolyte slowly
evaporates due to heat formed on charge and discharge and also due to
gassing on overcharge. The sulphuric
acid, however, does not evaporate,
and, consequently, the solution be-
comes denser. This loss of water due
to evaporation must, therefore, be
made up by adding only pure water.
The amount of evaporation will de-
pend on the temperature and on the
amount of work done by the battery,
and is a varying quantity; but a safe
rule to follow is to replace the water,
lost by evaporation, every week in
summer and every two weeks in
winter, during ordinary use of the
car. If the car is out of service,
water should be added once every
two weeks in summer and once a
month in winter before it is given a
refreshing charge. During cross-country touring it is good practice to
add distilled water every 200 miles of travel or once a day. The hydrom-
eter syringe may be used for adding the water. Enough water should
be added to keep the level of the electrolyte at all times up to the bottom
of the inside cover, or % to J^ in. above the tops of the plates, as shown in
Fig. 308. The cells should never be filled above this level. The electro-
lyte expands when charging, due both to increase in temperature and to
the gas bubbles which rise from the plates, therefore space must be
allowed for expansion. The battery if filled too full will run over,
resulting, not only in loss of electrolyte, but in the eating away of the
battery box and in the serious corrosion of the battery terminals and
connectors. Short circuits may also result from the film of electrolyte
on the top of the battery.
Fio
308. — Section of storage cell show-
ing proper level of electrolyte.
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THE AUTOMOBILE STORAGE BATTERY
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203. Necessity of Adding Pure Water. — Only absolutely pure water,
such as distilled water, should be used in filling the battery. Distilled
water is obtained by boiling water, catching the steam that comes off,
and condensing it into a liquid. Distilled water can usually be obtained
at any drug store or garage and must be kept in an acid-proof vessel.
A common way of storing it is in a glass bottle or jug. Water which has
merely been boiled should not be used. If distilled water is hard to
obtain, melted artificial ice, or filtered rain water which has not come
into contact with iron pipes or tin roofs, may be used. A common way
of collecting the latter is to catch the rain directly in an earthenware
jar set out after it has been raining for about 5 or 10 minutes. This is
to insure that there are no impurities in the form of
gases and small solid particles taken into the water
on its journey from the clouds. The use of spring,
river, hydrant, or well water should also be avoided
as these are liable to contain iron or other substances
detrimental to the life of the battery.
204. Cause of Specific Gravity Change.— The
specific gravity of the electrolyte in a fully charged
battery should be .between 1.275 and 1.300. This
specific gravity becomes lower as the battery be-
comes discharged. At the same time that the bat-
tery discharges its current, the acid which is in the
electrolyte, leaves the water and goes into the plates,
thus lowering the specific gravity of the solution.
Then, upon charging the battery, the acid is driven
out of the plates back into solution witji the water,
causing the specific gravity to rise. The amount
of specific gravity change is directly proportional to
the state of charge of the battery, so, by merely test- Fiq. 309.— Hydrom-
ing the gravity of the electrolyte, the exact state eter syringe.
of charge of the battery can at once be determined.
, 205. The Hydrometer. — A convenient way of testing the specific
gravity of the electrolyte is by the hydrometer syringe, as shown in Fig.
309. This instrument consists of a large glass tube syringe within
which is a small elongated glass hydrometer float with a vertical cylinder
graduated from 1.100 to 1.300. The rubber bulb at the top is used to
draw the liquid into the instrument. Normally, the hydrometer rests
on the bottom, but as soon as a liquid with a specific gravity greater
than water is drawn into the syringe, the hydrometer floats at a depth
according to the specific gravity of the liquid. The graduation on the
scale in line with the surface of the electrolyte is the reading of the specific
gravity of the solution. For convenience, its reading is spoken of as
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248 THE GASOLINE AUTOMOBILE
being 1160, 1200, 1280, 1300, etc., instead of 1.15, 1.2, 1.28, and 1.3
which is of course correct. The hydrometer syringe is also used for
adding water to the cells.
206. Hydrometer Readings. — Before taking a hydrometer reading,
the top of the battery should be cleaned off carefully before removing the
vent caps or plugs. This is to prevent dirt or other injurious substances
from getting inside the cell. .The rubber bulb is squeezed and the tube
of the syringe inserted into the cell until it rests on top of the plates.
The pressure on the bulb is now released until enough electrolyte is
drawn up into the tube to float the hydrometer freely. The line on the
hydrometer on a level with the surface of the liquid is the specific gravity
reading. The hydrometer must be held steady so that neither the float
nor the liquid moves while taking a reading. Care must be taken that
the float does not cling to the side of the syringe. After the reading has
been taken the liquid should be returned to the cell from which it was
withdrawn.
If there is not enough electrolyte in the cell to permit a hydrometer
reading to be taken, pure distilled water must first be added until the
electrolyte is up to the proper level. A hydibmeter reading taken directly
after adding distilled water is of no value as the water will remain at
the top of the cell. The battery must then be charged for at least one-half
hour, either by driving the car or by letting the engine run idle. This
mixes the water thoroughly with the electrolyte. Hydrometer readings
must be taken for all cells as described above, since they are not connected
internally.
Specific gravity readings from 1.275 to 1.300 indicate that the
battery is fully charged. Specific gravity readings between 1.200 and
1.225 indicate that the battery is more than half discharged, and starter
and lamps should be used sparingly until the battery is again fully charged.
Specific gravity readings between 1.150 and 1.200 indicate that the battery
is Hearing a discharged condition and immediate charging is necessary,
otherwise serious damage will result. Below 1.150 the battery is prac-
tically discharged and an effort should be made immediately to bring it
back to a charged condition by means of the generator on the car; If
this cannot be done, the battery must be removed from the car and
charged from an outside source.
207. Variation in Cell Readings. — If the specific gravity in any cell
tests more than 25 points lower than the other cells in a battery, it is
an indication that this cell is out of order. One reading to determine
the specific gravity of a cell is not sufficient. Several readings should
be taken and the average determined. Variation in cell readings may be
due to short circuits inside the cell; putting too much water in the cell
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THE AUTOMOBILE STORAGE BATTERY 249
causing the electrolyte to overflow; or to loss of electrolyte due to a
cracked or leaky jar.
Low specific gravity in one or more cells can very often be brought
up by driving the car (using starter and lights sparingly), or charging
by means of the generator with the engine running idle in which case
readings ought to be taken at frequent intervals. If the specific gravity
in any cell does not come up to at least 1.260 after the other cell readings
indicate that the battery is fully charged, it is an indication that the low
cell is in need of internal adjustment. This can only be done by an
experienced battery repair man. Most battery troubles can be traced to
the electrolyte becoming too low in the cells. The effect of this is to
weaken the battery, thus permitting it to be more easily discharged, and
frequently causing harmful sulphation of the plates and injury to the
separators. This may allow the plates to come together, causing internal
short circuits. It is very important, therefore, that pure distilled water
be added regularly to all cells in order to keep the electrolyte up to the
level specified by the manufacturer.*
If the battery does not regain its full power and efficiency within
one or two days, after continuous charging on the car, as explained
above, it is an indication that the battery is badly sulphated, or has some
other internal trouble. It should receive immediate attention from a
competent battery man, otherwise the battery may be entirely ruined.
A frequent cause for the electrolyte being low in one or more cells is the
presence of a cracked or leaky jar. If one cell needs more frequent
addition of water than the other cells, it is a good indication that the jar
leaks. This condition calls for immediate action, as the trouble can
very easily be corrected if the battery is taken to a service station at
once and a new jar installed. If the cracked or leaky jar is not immedi-
ately replaced, the cell will be totally ruined and very likely the entire
battery seriously damaged. Jars are frequently broken due to the
battery hold-downs coming loose, allowing the battery to jolt around;
or to freezing of the electrolyte in cold weather.
206. Variation in Hydrometer Readings Caused by Temperature. —
All the definite figures given in hydrometer readings are based on the
normal temperature of 70°F. for the electrolyte. This refers strictly to
the temperature of the liquid itself, and not to the temperature of the
surrounding atmosphere. The weather might be freezing cold, and yet
the temperature of the liquid solution in the battery might be normal or
above, either from the heat of the engine or because the battery was
being vigorously charged.
A special inexpensive battery thermometer is needed to take
the temperature of a battery. The thermometer is inserted through the
vent plug-hole into the liquid, in the same way as a hydrometer. The
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rule in making temperature correction is that for every 3° above 70°F.,
0.001 be added to the hydrometer reading; and for every 3° below 70°F.,
0.001 be subtracted from the observed reading. For example: The
temperature at end of charge is 120°F. and the observed gravity reading
is 1.260. The corrected reading is determined as follows:
Corrected reading
120° - 70° = 50°
60 -s- 3 = 17 (approx.)
17 X 0.001 =0.017
1.260 + 0.017 =1.277
If the reading at 0°F. is 1.210, then
Corrected reading:
70° - 0° - 70°
70 ^ 3 = 23
23 X 0.001 =0.023
1.210 - 0.023 = 1.187
From the above it can be seen that temperature must be taken into
consideration, otherwise the hydrometer reading will be misleading. It is
usually unnecessary to make allowance for temperature variations, but
it is well to bear them in mind, particularly in the case of a battery which
has been giving trouble.
Another thing to remember in this connection is that, in hot weather,
if the temperature of the liquid is more than 20 degrees in excess of the
temperature of its immediate surroundings, it indicates that the battery
is possibly being overcharged or being charged at too high a rate, or is
in a bad condition. This, however, cannot be given as a positive rule.
In theory, the temperature of the liquid in a battery should never exceed
105°F., as high temperatures have an injurious effect and tend to
shorten the life of the battery; but as long as batteries are carried in
locations subjected to engine heat, and used on automobiles in hot cli-
mates, ideal conditions do not exist and the battery must get along as well
as it can.
209. Freezing Temperature of the Battery. — The following table gives
the state of charge and the freezing temperatures of the storage battery
at different specific gravities.
Specific gravity
Condition of battery
Freesing point in degree*
Fahrenheit
1.275 to 1.300
1.260
1.210
1.160
1.120 or below
Fully charged
% charged
\i charged
y± charged
Completely discharged
90 degrees below zero
60 degrees below zero
20 degrees below zero
Zero
20 degrees above zero
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THE AUTOMOBILE STORAGE BATTERY
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It will be noted that the freezing point of electrolyte depends upon
its specific gravity and the condition of battery charge. Therefore, to
prevent a battery from freezing, it should be kept in a fully charged
condition.
If it becomes necessary to add water to the battery in cold weather,
this should be done just before running the engine. In very cold weather,
however, it is better to start the engine and have the battery charging
before the water is added. This is done because water, being lighter than
electrolyte, remains on the surface of the liquid in the cells until circulated
and mixed by the charging current. If water .is added, therefore, and
Fio. 310. — Effect of freezing on battery
plates.
Fio. 311. — Cracked battery jar due to
freesing.
the battery allowed to stand for a time without charging, there is a
possibility of freezing the water on the surface of the solution.
210. Results of Freezing. — The results of a frozen battery can be
seen in Figs. 310 and 311. Owing to the discharged condition nearly all
the acid has entered the plates, leaving water, with only a small propor-
tion of acid, surrounding them. The result is that the water froze at
quite a high temperature, and as it froze the little particles of ice ex-
panded, loosened the material, and even cracked the grids containing it.
As soon as a charge is given a frozen battery, the grids expand and the
loosened material drops to the bottom, leaving the grids exposed as shown
in the illustration. The whole battery becomes disintegrated simply
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THE GASOLINE AUTOMOBILE
due to the fact that it was attacked by cold while in a discharged
condition.
The battery should be fully charged when it is put away for the winter
and should be given an additional charge every three or four weeks
to bring it up to its proper gravity reading. If the car is put away for
the winter and charging is neglected, a battery that readily starts the
engine in the fall may be nothing but a container and a mass of muddy,
disintegrated material in the spring.
211. Battery Charging. — When batteries are charged from an outside
source, only Uirect current should be used. It. is not possible to charge
batteries from an alternating current supply without apparatus to convert
it into direct current — either a motor-generator or rectifier.
In charging, the positive wire of the charging circuit must always be
connected to the positive (+) terminal of the battery. If this is reversed,
serious injury may result to the battery. The charging wires may be
SWITCH
m&m-
Fia. 312. — Charging batteries from 110-volt D.C. supply, using rheostat for resistance.
tested for polarity either by using a voltmeter or by immersing the ends
of the wires in a glass of water to which a few drops of acid or a little salt
have been added, when excessive bubbles will form on the negative wire.
In charging from a 110-volt direct-current supply it is necessary
to introduce either a rheostat (an adjustable resistance unit), Fig. 312,
or a bank of lamps in series with the battery in order to regulate the
flow of charging current. When using a lamp bank as in Fig. 313, to
regulate the rate of current, 110-volt, 32 c.p. carbon filament lamps should
be used, connected in parallel with each other, and the combination in
series with the battery. With this arrangement, each lamp will allow
about one ampere of charging current to pass through the battery so
that the number of lamps in use will be approximately equal to the
number of amperes of current to be used in charging. The charging
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THE AUTOMOBILE STORAGE BATTERY
253
rate may be adjusted by turning the lights off or on, or by moving the
rheostat handle until the ammeter shows the proper reading.
Where more than one battery is to be charged at a time, the batteries
should be connected in series; that is, the positive terminal of one battery
should be connected to the negative terminal of the adjoining battery.
Rubber-covered copper wire (No. 14 or larger) cut in lengths of about
18 in. should be used to connect batteries in this manner. The wire
is connected to the terminals, either by clips attached to the ends of the
wires, or by twisting the wire around the terminals. Care should be
taken to see that a good contact is made without damaging the terminals.
The total voltage of a combination of batteries is the sum of all the
cells in the circuit multiplied by the voltage of each cell (2 volts). In
charging batteries, each cell requires 2.5 volts; therefore, care should be
taken that the total voltage required for charging all the cells does not
110 V.-D.C SUPPLY
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BATTERIES TO BE CHARGED
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Fig. 313. — Charging batteries from 110-volt D.C. supply, using lamps for resistance.*
equal the operating voltage of the generator. Should the total voltage of
the cells, while on charge, equal the voltage of the generator, no current
will pass through the batteries. Should the total voltage of the cells
exceed the voltage of the generator, the batteries will discharge them-
selves through the generator. When charging several batteries in series,
care should be taken to see that the charging rate does not exceed the
maximum rate of the battery requiring the lowest charging current.
The charging rate of most batteries is marked on the name plate, in
fact, usually two rates, the start and finish rates, are given. The reason
for this is that it is much better for the battery if the charging rate is
reduced when approaching a full state of charge, to avoid excessive
heating and evaporation of the electrolyte. If the charging rates are
not marked on the battery, a safe charging rate at the start would be
about 10 per cent, of the rated ampere-hour capacity, and 5 per cent, of
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264 THE GASOLINE AUTOMOBILE
this rating to finish ; for example, in the case of an 80 ampere-hour battery,
the charging rate^t the start should be 10 per cent, of 80 or 8 amperes,
and at the finish 5 per cent, of 80 or 4 amperes. If- the ampere-hour
capacity is not known, the charging rate at the start may be 8 to 10 am-
peres, but should be reduced to a lower rate if any of the cells show signs
of heating.
212. Detailed Instruction for Charging Batteries. — Before placing the
battery on charge, or removing the vent plugs (or caps), the top should
be thoroughly cleaned off to prevent any dirt or impurities from falling
into the cells. If any of the cells or outside battery parts are corroded,
the corrosion should be cleaned off with a solution of ordinary washing
soda and water, applied with a clean cloth or sponge. The vent plugs
(or caps) are now removed and should not be replaced until the battery is
removed from the charging circuit, unless a special type of filler tube,
which requires the plug to remain in place while the battery is charging,
is used. In this case, the plug is removed only when it is necessary to
take a hydrometer reading or add distilled water. Distilled water should
be added to all cells in sufficient quantities to bring the electrolyte up
to the proper level, which in most batteries is one-half inch above the
top of the plates.
The battery is placed on charge at the start rate specified on the name
plate and the voltage of each cell tested immediately. The voltage and
hydrometer readings of each cell should be made every hour. The
charge at the start rate should continue until one or more of the cells are
gassing vigorously and the voltage of each cell reads 2.4 or higher.
The charging rate should then be reduced to the finish rate and
charging continued at this rate until the battery is fully charged.
A battery is fully charged when, with the current flowing at the
finish rate, all cells are gassing vigorously; the voltage and specific gravity
of each cell have stopped rising and have been constant for one hour;
the voltage reading is 2.4 or higher per cell on charge; and the specific
gravity of each cell tests between 1.275 and 1.300.
Although it is always advisable to use a voltmeter in battery charging
it is not absolutely essential. When a voltmeter is not used, the start
rate should be continued until the battery is gassing vigorously. The
rate should then be reduced to the finish rate and charging continued
until the specific gravity of all cells has stopped rising and remains con-
stant for one hour. If the specific gravity rises above 1.300 while the
battery is on charge, part of the electrolyte should be drawn from the
cells and enough distilled water added to reduce the specific gravity to
1.285. If, on the other hand, the specific gravity will not come up to
1.275 by continuous charging it indicates that there is insufficient acid
in the electrolyte. The specific gravity should be corrected by removing
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THE AUTOMOBILE STORAGE BATTERY
255
some of the electrolyte from the defective cell and replacing it with a like
amount of electrolyte of 1.350 to 1.400 sp. gr. Pure acid should never
be added to a battery as it will gas and heat violently and will damage
the plates and separators. Figure 314 shows the effect on wood sepa-
rators by filling the cell with pure acid solution. After the specific
gravity has been adjusted, the battery should remain on charge for at
least one hour. The voltage at the completion of charge should be about
2.5 volts for each cell but this will immediately drop to approximately
2.2 volts per cell making the voltage of a fully charged three-cell battery
about 6.6 volts. The voltage, however, will vary slightly with the
temperature.
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Pia. 314. — Effect of strong electrolyte on wood separator.
Caution. — Care should be taken to keep open flames away from a
battery which is or has been charging or discharging. The gas which
accumulates in the cells, due to the chemical action, is combustible and
may cause sufficient explosion to wreck the battery and injure the
operator.
After the battery has been removed from the charging line, the vent
caps should be screwed tightly into place and the battery top and con-
necting terminals cleaned with either soda solution or ammonia water.
To prevent corrosion of the battery terminals, they should be greased
with a light coat of vaseline or soft grease.
213. Battery Testing with the Voltmeter.— The chief use of the volt-
meter is to determine the positive and negative terminals of the cells
and the individual cell voltages on charge and discharge. A convenient
instrument to use is a low-reading voltmeter having a scale from 0 to
3 volts. The leads should be equipped with sharp prods. These prods
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256
THE GASOLINE AUTOMOBILE
are pressed into the terminals of each cell until a good connection is made.
When the voltmeter reads in the right direction, the terminal of the cell
connected with the plus or positive voltmeter lead is the positive terminal.
The positive terminal of one cell should be connected to the negative
terminal of the next cell. If this has not been done, the cells are not
assembled correctly in the battery case and they should be reassembled.
A fully charged cell while on charge should read from 2.4 to 2.6 volts,
depending on the age of the battery and the amount of charging current
flowing through the battery. It should read about 1.8 volts when nearly
discharged with the battery discharging at a current of about 5 amperes.
When a cell is floating (neither charging nor discharging) the voltage
should be about 2.1 to 2.2.
Fio. 315. — Sulphation of battery plates
due to undercharging.
Fio. 316. — Sulphation due to underfilling
of battery.
214. Sulphation. — It was found that upon the discharge of the bat-
tery, the plates were acted upon by the sulphuric acid in the electrolyte,
converting the lead peroxide of the positives and the pure spongy metallic
lead of the negatives into a lead sulphate, which upon charging is again
converted back into its original form. When the plates are permitted to
remain in a discharged condition, the lead sulphate grows into a hard,
white, crystalline formation, which closes up the pores and destroys the
active area of the plates. This formation is known as sulphation.
Figure 315 shows a positive group of a battery with wood separators
that has been operated in a partially discharged condition for some length
of time. The white area on the plate indicates the sulphation.
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THE AUTOMOBILE STORAGE BATTERY
267
Sulphation is also caused by low electrolyte or because the cell has
not been filled with water. If water is not added at regular intervals to
replace loss through evaporation, the electrolyte level will soon fall below
the plate tops, causing that portion of the plates which is exposed to the
air to sulphate rapidly. Figure 316 shows a sulphated condition of plates
after a few months1 use (or rather misuse) produced by a lack of water and
by allowing the solution to become low and not cover the plates. A hard
white sulphate has formed on the top half of the plates. It is difficult
and sometimes impossible to even charge and bring back to a normal
condition a plate that has dried out and become hard. The concentrated
condition of the electrolyte (only the water evaporates) is also injurious to
the lower half of the plates and separators. Sulphate is a non-conductor
Fio. 317. — Effect of overfilling the battery.
of electricity, therefore it is quite destructive to the activity of the plates
and reduces materially the ampere-hour capacity of the battery. For
example, the capacity of a 100 ampere-hour battery in which one-half
of the plate area is sealed up by sulphation would be reduced approxi-
mately 50 per cent, and would be capable of no more work than a battery
of 50 ampere-hour capacity. Sulphation can be removed if not too bad
only by prolonged charging at a very slow rate, usually the finish rate
for the battery. It may require charging for several days to restore it
to a fully charged condition.
In order to prevent sulphation, the battery should be kept charged and
the plates well covered with electrolyte.
215. Effect of Overfilling. — The effect of overfilling a battery is well
illustrated by Fig. 317. The battery should be filled with water up to
17
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258
THE GASOLINE AUTOMOBILE
the bottom of the cover tube, or % in. to % in. above the top of the
plates. If it is filled above this point it will run over upon charging,
due to the lack of space for expansion. This will result in a loss of the
electrolyte and an eating away of the battery box, as indicated. The
electrolyte may also get into the metal case and eat out the bottom.
216. Corroded Terminals. — Frequently, the terminals and connectors
will be found covered with a greenish deposit. This is a corrosion due
to the acid fumes which are constantly passing off from the cells and
attacking the metal connectors. Figure 318 shows a cable terminal badly
corroded by the splashing or spraying of electrolyte on the bare cable
wires where insulation has been stripped off.
The eating action may be stopped and all corrosion removed by
soaking the parts in a solution of bicarbonate of soda (common baking
soda) or ammonia and brushing them with a stiff brush after which they
should be wiped dry. Further corrosion will be prevented by covering
the parts with a light coat of vaseline or cup grease.
Fig. 318. — Effect of corrosion on battery cable terminals.
217. Disintegrated and Buckled Plates. — Overheating of the plates,
through excessive charging or discharging, causes them to warp or
buckle. It also causes disintegration of the active material, especially
in the positive plates. Figure 319 shows what continuous overcharging
does to the positive plates. It softens up the material and causes the
battery to give unusually high capacity for a short time. The material
then begins to disintegrate and fall out. The effect is about the same as
freezing. In order to determine which condition has existed, it should
be remembered that overheating usually blackens and softens the wood
separators.
A plate is especially liable to buckle when in a sulphated condition,
if discharged or charged at a high rate. The sulphated portion of the
plate does not expand at the same rate as the active area, thus causing
unusual expansion and a warping, sometimes cracking, of the grid.
A group which has been allowed to stand discharged at a low point for some
time, then charged at a high rate to restore its energy, is shown in Fig.
320. On account of the hardness of the plates and the extra resistance
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THE AUTOMOBILE STORAGE BATTERY
259
of the sulphate formed during the excessively low period of discharge, the
plates become very hot and being only slightly flexible or elastic, warp
or buckle when expanded by heat. This illustration, Fig. 320, shows the
difference between a cell continuously overcharged and one which has
been allowed to discharge and become hard. Buckling also causes a
breaking down of the separators and often results in cracking the jar,
as in Fig. 321, with a loss of the electrolyte.
To avoid overheating and buckling of the plates, the following
precautions should be taken:
Fio. 319. — Effect on battery plates of
continuous overheating.
Fio. 320.— Buckled battery plates.
1. Prevent sulphation through keeping battery charged and properly
filled.
2. Make sure that the generator is adjusted to charge the battery
at the proper rate.
3. Do not operate the starting motor excessively.
4. Do not propel the car with the starter.
5. Watch the battery temperature in hot weather, and when touring.
If the top connectors feel warm to the hand, drive with the headlights
on to cut down the charging rate.
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260
THE GASOLINE AUTOMOBILE
218. Sediment — When a battery is used, a deposit known as sedi-
ment collects in the bottom of the jars, due to the gradual wearing away
of the active material in the plates. Figure 322 shows a worn-out plate
from which practically all the active material has fallen. In time, this
sediment may fill up the sediment or mud space, causing a phort-circuiting
of the bottom of the plates. In this event, the cell must be dismantled
and the sediment removed. Broken down insulation due to high sedi-
ment or defective separators is indicated by the inability of a cell to
hold a charge on open circuit. Other indications of broken down
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Fig. 321. — Cracked jar due to
buckled plates.
Fio. 322. — A worn-out battery -plate show-
ing the active material fallen out and the grid
exposed.
insulators are: undue heating of the cells upon charging, little or no
voltage or gravity rise after a prolonged charge, and the impossibility
of making the cells gas properly. Such a cell is considered dead and can
be remedied only by dismantling and rebuilding the battery. This is a
job which should be undertaken only by an experienced battery repair-
man, as it involves lead burning with either a hydrogen or oxy-acetylene
flame, an art in itself, requiring special lead burning equipment and much
practice.
219. Conditions Causing the Battery to Run Down. — It is impossible
to include here all the conditions which may cause the battery in the
electrical system to run down, since many of the causes may be due to
faults in the starting and generating system. However, a few of the
most important causes are given to assist in diagnosing battery trouble
on the automobile.
A discharged or weak condition of the battery, which is indicated
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THE AUTOMOBILE STORAGE BATTERY 261
by a loss in cranking power of the starter, dim lights, low specific gravity,
etc., may be attributed to one of the following causes:
1. Generator either not charging battery or charging at insufficient
rate.
2. Battery plates not kept properly covered with electrolyte, causing
sulphation of the plates.
3. Drain on battery dye to excessive lamp load or too many electrical
accessories not intended for the battery.
4. Engine not driven fast enough to charge at sufficient rate.
5. Too much night driving with full lamp load on.
6. Excessive use of the starting motor; starting switch sticking.
7. Electrical cut-out not operating properly.
8. Battery ignition switch left "on" with engine not running.
9. Cracked jar causing loss of electrolyte.
10. Broken down battery insulation due to high sediment or defective
separators.
11. Loose generators, cut-out, or battery connections.
12. Corroded battery terminals.
13. Overfilling, causing loss of electrolyte and short circuits.
14. Use of impure water for filling.
15. Battery too small to meet requirements of the system.
16. Short circuits in the electrical wiring.
17. Grounded generator or motor armature winding.
18. Battery freezing.
19. Plates broken loose from terminal or connector.
20. Battery plates worn out.
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CHAPTER X
STARTING AND LIGHTING SYSTEMS
220. Automobile Starters. — Devices for starting automobile engines
may be classified into four general types, according to the source of
energy for turning the engine crankshaft until the engine operates under
its own power. These four general types are; mechanical starters, air
starters, acetylene starters, and electric starters.
221. Mechanical Starters. — Mechanical starters include the various
types of hand-cranking devices and springs. The disadvantage of the
hand-cranking starter is that it requires a certain amount of human
power. The only advantage is that the driver usually does not have to
leave his seat to crank the engine. One type of mechanical starter is
the spring starter. It is capable of giving the engine a few revolutions
only, and if the engine does not start then it becomes necessary for the
driver to wind up the spring, which is a rather tiresome operation. If
the engine starts, there is an automatic device by which the spring is
wound up by the engine.
222. Air Starters. — In the air starters, the air is pumped into a storage
tank to about 150 lb. pressure. The engine is started either by admitting
air into the combustion chamber or by cranking it by means of a com-
pressed-air motor. In the first method, the pipe leading from the tank
goes to an air distributor which is driven by the engine, the air being
directed to the various cylinders in accordance to their firing order.
The air enters each cylinder when it is on its working stroke, at which
time all the valves are closed. The method of starting by air has the
disadvantage that the air is liable to cool the cylinders sufficient to
prevent proper starting of the regular engine cycle on account of the
fuel charge condensing on the cool cylinder walls. Another disadvantage
in using air for starting is the difficulty in preventing air leaks, since the
system is necessarily under comparatively high pressure and subject
to continuous vibration.
223. Acetylene Starters. — Some manufacturers have equipped their
machines with a device for starting with acetylene gas. This gas is very
explosive and will ignite readily under almost any condition. These
engines are equipped with valves and tubes from the acetylene lighting
system so that the driver can inject a small quantity of acetylene gas
into the cylinder. The engine will then be practically sure of starting
on the spark.
263
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264 THE GASOLINE AUTOMOBILE
224. Electric Starters. — The mechanical, air, and acetylene starters
have practically been discarded in favor of the electric starter which is
now universally used and is furnished as standard equipment by the
manufacturer on all makes of passenger cars and on a large percentage
of trucks. The electric starter is in the form of a low-voltage direct-
current motor. The current for operating this motor is supplied by a
storage battery which also furnishes the current for the lighting system
and, in many cases, for the ignition.
The typical electric starting and lighting system consists essentially
of the following component parts:
1. A direct-current starting motor which will operate on current from
the storage battery for cranking the engine.
2. A storage battery for supplying current when the generator is not
running or is not running fast enough to generate the required amount
of current.
3. A direct-current generator for keeping the battery charged.
Electric starting and lighting systems may be divided into two general
classes according to the number of machines required to perform the
generating and cranking operations, namely, the single-unit and two-unit
systems. In the single-unit system the generator and starting motor
are both combined into one machine known as a " motor-generator' ' or
"starter-generator." In this system the machine operates as a motor
using current from the battery for cranking the engine, and converts
itself automatically into a generator to charge the battery when it is
driven by the engine. In the two-unit or "double-unit" system the
generator and starting motor are separate and comprise two independent
machines. In this type of system the generator is driven continuously
by the engine, while the starting motor is normally disconnected from the
engine through its driving mechanism and operates only when the engine
is to be cranked and the starting switch is closed. A wiring diagram and
installation of a typical two-unit system are shown in Fig. 323. From
this diagram it will be noticed that the current for the ignition, horn,
lights, starting motor, etc., returns to the battery through the ground
or frame of the car, instead of by a separate wire. An electric system
employing this method of wiring is termed a single-wire grounded system.
This method of car wiring, in preference to the two-wire method, is used
by practically all automobile manufacturers, since the use of the frame as
one wire greatly simplifies both the wiring of the car and in many cases
the construction of the starting and lighting apparatus.
The voltage at which the system operates is usually 6 volts although
in some installations, 12 volts are used. In many of the first systems
brought out, a double voltage or split battery was used such as the 6 volt
-12 volt, 12 volt-24 volt, and the 6 volt-24 volt types. The cells of
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STARTING AND LIGHTING SYSTEMS
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266
THE GASOLINE AUTOMOBILE
the battery were divided into two groups connected normally in parallel
giving the lower voltage when being charged and for operating the
lights, but connected in series with the starting switch closed, to
give the higher voltage for operating the starting motor. However,
owing to the many disadvantages of the double voltage system it has
been practically discarded in favor of the single 6-volt system using a
3-cell battery. The voltage of the system can readily be determined by
looking at the storage battery, since a 6-volt system uses a 3-cell battery
and a 12-volt system a 6-cell battery.
225. Hydraulic Analogy of an Electric Starting and Lighting System.
— The operation and function of the different parts of a starting and light-
HORN
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Fig. 324. — Hydraulic analogy of electric starting and lighting syBtem.
ing system may be compared to the operation of a small waterworks
system such as is commonly used in small towns or private residences.
This hydraulic analogy is shown in Fig. 324.
Such a water system usually comprises a motor-driven pump, con-
nected by a main line to the various outlets, and a tank or reservoir
placed at a height which will give the desired head or pressure.
The pressure tank or reservoir is provided with a regulator, usually
of the float type, adapted to indicate the amount of water in the reservoir
and to shut off or reduce automatically the power of the pump when the
water has reached a certain predetermined level. This regulation may
be accomplished by connecting a float regulator to a switch or rheostat
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STARTING AND LIGHTING SYSTEMS 267
(adjustable resistance) in the main circuit of the motor which drives the
pump so that the speed of the motor and the output of the pump will be
regulated in accordance with the quantity of water being drawn from the
system. If the quantity of water drawn from the system is in excess of
the quantity supplied by the pump at a given speed, the reservoir will
supply the difference, and when the level of the water falls to a certain
point, the motor will be caused to run faster, thus making up for the
greater demand.
A check valve is placed in the main line between the pump and the
reservoir. The purpose of this is to prevent the backward flow of water
into the pump in case the pressure due to the water in the reservoir
exceeds that of the pump or in case the pump is stopped.
The reservoir in the water system corresponds to the storage battery
in the starting and lighting system, the pump to the generator which is
driven by the engine, the float regulating device to the regulating relay
for controlling generator output, and the check valve to the cut-out of
the electric system. The meter registers the amount of water either
pumped into or discharged from the reservoir and corresponds to the
ammeter, Fig. 323, connected in the generator charging circuit. When
the current output of the generator exceeds the amount required by the
lights, ignition, etc., the excess current will flow through the battery in a
charging direction so that the ammeter will show "charge." For
example, if the lamps require 8 amperes and the generator output is
12 amperes, the ammeter will show 4 amperes charge. On the other
hand, if the generator is only supplying 8 amperes, the same as required
by the lights, the battery will neither charge nor discharge and the
ammeter will read zero. But if the generator produces less than that
required by the lights, say only 5 amperes, the battery will supply the
amount which the generator is deficient and the ammeter will show 3
amperes discharge. It will be noticed in the diagram that the current
for the starting motor will not pass through the ammeter, since the motor
requires a very large current which may be sufficient to burn out the instru-
ment. Providing the lamps are of the proper size, the generator output
should be so regulated that at normal driving speeds, with all lights and
ignition turned on, there will be at least 3 or 4 amperes charging the battery.
This is necssary to compensate for the current used periodically by the
starting motor and horn and in order to keep the battery fully charged.
By making a few minor changes, such as forming a by-pass around
the check valve, the analogy of Fig. 324 will apply equally well to the
single-unit system, in which case the pump will act as a water motor
when the valve in the by-pass is opened and the water discharged through
it from the reservoir. The pump now corresponds in action to the motor-
generator, and the valve in the by-pass to the starting switch, which,
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268
THE GASOLINE AUTOMOBILE
by short-circuiting the cut-out, permits the battery to discharge through
the motor.
With this connection, it will be noted that the ammeter must now
carry the starting current. Since the starting current is usually more
than the ammeter is designed to carry, the ammeter must either be elimi-
nated or replaced by a battery indicator capable of carrying a large current.
The battery indicator does not register the number of amperes flowing
but merely indicates which way the current is flowing through the battery.
It is usually referred to as the C. O. D. indicator; due to the fact that
it has three readings, "charge," "off," and "discharge."
226. Generator Drives. — The method of mounting and driving the
generator depends to a large extent upon whether the engine has four,
six, eight, or twelve cylinders. For this reason, it is more or less of
Fio. 325. — Westinghouse generator installation on Case-Continental Six engine.
an individual problem on the different makes of cars. In the two-unit
system, which is the type now most commonly used, the generator is
usually mounted on the side of the engine and driven 1 to 1% times crank-
shaft speed. The method of drive may be by belt, silent chain, or gears,
the gear drive being the most popular method. One typical generator
mounting is that shown in Fig. 325, in which is shown the installation
of the Westinghouse generator on the Case-Continental Six engine. The
generator is supported by a bracket on the upper half of the crank case
and is driven by a coupling on the rear end of the pump shaft which is
driven through gears from the crankshaft at 1^ times crankshaft speed.
By mounting the generator in this manner it is possible to remove it
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STARTING AND LIGHTING SYSTEMS
269
without disturbing other parts of the engine. The flexible coupling in-
sures proper driving of the generator, although it may not be in exact
alignment with the driving shaft.
Another method of supporting the generator is to provide it with
flanges, as shown in Fig. 326. The generator flanges are bolted directly
Fio. 326. — Westinghouse generator with flange mounting.
to the timing gear housing. The pinion on the generator armature shaft
meshes directly with one of the timing gears, thus eliminating the drive
shaft and coupling. This method of installation gives a very rigid mount-
ing, insures perfect alignment of the bearings, and makes the generator
very accessible in case it is to be removed for repair.
IGNITION
GENERATOR
Fio. 327. — Installation of Delco starting, lighting, and ignition equipment on Nash Six.
The method of mounting the Delco electrical equipment on the Nash
Six is shown in Fig. 327. The generator is mounted on the front of the
cylinder casting, being fastened by machine studs passing through the
flanges of the generator frame. The fan and the pulley, for driving both
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THE GASOLINE AUTOMOBILE
the fan and the generator, are mounted upon the forward end of the
generator shaft. The generator is driven by a V belt from the pulley
on the forward end of the crankshaft at approximately 1H times crank-
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Fig. 328. — Westinghouse starting motor installation on Case- Continental Six engine.
shaft speed. The oblong holes in the flanges through which the studs
pass permit adjusting of the belt tension.
227. Starting Motor Drives. — The starting motor is usually mounted
on the side of the engine by means of a bracket or flange connection to
SturTtR FORK SPAING
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Fig. 329. — Sliding pinion type of motor drive.
the cylinder casting, similar to the generator mounting. Typical instal-
lations are shown in Figs. 327 and 328. In Fig. 327, the rear end of
the starting motor casting has a machined neck which fits into a cylin-
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STARTING AND LIGHTING SYSTEMS
271
drical hole in the flywheel housing, the motor being held in place by a
single set screw. The starting motor may drive the engine through a
silent chain and overrunning clutch, or by a pinion attached to the
motor armature shaft which is brought into mesh with teeth cut on the
rim of the flywheel. The latter method has many advantages and is
used almost universally on two-unit systems, while the chain drive is
used more extensively on single-unit systems.
There are three principal methods of connecting the motor to the
flywheel: (1) the sliding pinion type, Fig. 329, in Which a pinion is shifted
by the operator as the starting switch is closed, the operation of which
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Fig. 330. — Sectional views of Bosch starting motor with magnetically shifted armature
for engaging pinion with flywheel, (A) showing pinion out of engagement and (B) showing
pinion engaged.
depends more or less on the skill of the operator; (2) the magnetic type,
Pig. 330, in which the entire armature is automatically shifted by mag-
netism pulling the pinion into mesh; and (3) the Bendix drive, Fig. 331,
which is automatic and which requires very little attention and skill on
the part of the operator. The last method is used on practically all
makes of cars equipped with the two-unit system.
The gear reduction obtained through the flywheel type starter with
single reduction is usually about 11 or 12 to 1, that is, the speed of the
motor armature is 11 or 12 times that of the flywheel. With the single
reduction, the pinion gear on the armature shaft meshes directly with
the gear teeth on the flywheel, as in Figs. 323, 330, and 331. In some
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272
THE GASOLINE AUTOMOBILE
cases, however, a double reduction is used in which the gear ratio may
be as high as 25 or even 40 to 1. With the double reduction, as shown
in Fig. 332, the pinion gear A on the armature shaft does not mesh
directly with the teeth on the flywheel but with an intermediate gear B
Fig. 331. — Starting motors with inboard (upper) and outboard (Lower) Bendix drives.
which in turn drives the flywheel driving pinion. The double reduction
drive permits the use of a very small starting motor running at high
speed but it has the disadvantage of being more complicated than the
drive mechanism of the single reduction type.
Fig. 332. — Wagner starting motor with double reduction drive.
Owing to the high gear ratio between the starting motor and the
engine, in all starters of the flywheel type, some provision must be made
to prevent the engine from driving the motor at excessively high speeds
when the engine starts under its own power. In starters having the slid-
ing pinion type of drive, as shown in Fig. 329, this is taken care of by an
overrunning clutch incorporated in the intermediate gear which slips
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STARTING AND LIGHTING SYSTEMS 273
when the flywheel tends to drive the starting motor. Figure 333 shows
the construction of a typical overrunning clutch. In starters with either
the magnetic or Bendix type of drive the driving pinion is automatically
thrown out of mesh with the flywheel gear as the engine speeds up under
its own power.
228. The Bendix Drive. — The automatic screw pinion shift mechan-
ism, known as the Bendix drive, Fig. 331, is built in two distinct styles,
the inboard type in which the pinion shifts toward the motor to engage
with the flywheel, and the outboard type in which the pinion shifts away
from the motor. The outboard type requires a third bearing to support
the outer end of the shaft.
Fig. 333. — Gray and Davis overrunning clutch.
The construction of the inboard type is shown in Fig. 334. Mounted
en the extended armature shaft is a sleeve having screw threads (usually
a triple thread) with stops at each end to limit the lengthwise travel of
the pinion, which, having corresponding internal threads, is mounted on
this sleeve. This pinion is weighted on one side. The sleeve is connected
to the motor armature shaft through a coil spring attached to a collar
pinned to the armature shaft. The same method of construction is
used in the outboard type.
The operation of the Bendix drive is shown in Figs. 335 and 336.
Normally, the pinion is out of mesh and entirely away from the flywheel
gear. When the starting switch is closed and the full battery voltage is
impressed on the motor the armature immediately starts to rotate at
high speed. The pinion gear being weighted on one side and having
internal screw threads, will not rotate immediately with the shaft but,
due to its inertia, will run forward on the revolving screw sleeve until it
meets or meshes with the flywheel gear. If the teeth of the pinion and
18
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274
THE GASOLINE AUTOMOBILE
flywheel meet instead of meshing, the spring will allow the pinion to
revolve until it meshes with the flywheel. When the pinion is fully
meshed with the flywheel teeth, the spring compresses, and the pinion is
then driven by the motor through the spring and turns the engine over.
AUTOMATIC
WEIGHT
BOLT CONNECTION TO
ARMATURE SHAFT
Fio. 334. — Construction of Eclipse-Bendir drive.
CONNECTION TO ARM. SHAFT
CONNECTION TO SCREW
SHAFT
PINION
SCRtW SHAFT \ WEtCHT
STOR \
COLLAR
FLY WHEEL
Fig. 335. — Typical outboard Bendix drive installation.
The spring acts as a cushion while cranking the engine against compres-
sion. It also breaks the severity of the shock on the teeth when the
gears mesh, and in case of back-fire. When the engine fires and runs on
its own power, the flywheel drives this pinion at a higher speed than the
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STARTING AND LIGHTING SYSTEMS
275
armature, causing the pinion to be turned in the opposite direction on the
screw and to automatically demesh from the flywheel. This prevents the
engine from driving the starting motor. The centrifugal effect of
the weight on one side of the pinion, when automatically demeshed from
the flywheel, holds the pinion to the sleeve in a demeshed position until the
starting switch is opened and the motor armature comes to rest.
Fro. 336. — Operation of Bendix drive inboard type.
Among the chief advantages claimed for this type of motor drive are:
1. Simplicity of construction.
2. Mechanism automatic in operation, requiring no skill from the
operator.
3. High cranking speed, owing to the fact that the starting motor
is permitted to attain full speed before the load is applied.
DRIVING CHAIN
HOUSING
STARTER GENERATOR
Fro. 337. — North East starter-generator on Dodge oar.
4. The engine is given a high "break away" cranking torque, thus
requiring the minimum amount of cranking and minimizing the demand
on the battery.
5. Better carburetion and easier starting in cold weather.
229. Motor-generator Drives. — The North East starter-generator
installation on the Dodge car, Fig. 337, and the Dyneto installation on
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276
THE GASOLINE AUTOMOBILE
the Franklin car, Fig. 338, are typical installations of single-unit systems
in which the motor-generator is driven by a silent chain from the crank-
shaft. The gear ratio in these installations is usually 2% or 3 to 1 so that
the armature speed is 2% or 3 times the crankshaft speed when operating
Fio. 338. — Dyneto motor-generator installation on Franklin engine showing chain drive.
either as a generator or as a motor. No overrunning clutch is used.
Although the chain runs in oil, it will gradually lengthen through wear
and must be adjusted from time to time to prevent noise and "climbing"
of the sprockets. In the North East system on the Dodge, provision is
IGNITION COIL
STARTING PEDAL
1MIUG
GEARS
bRAMCOCK
DELCO C ENER.ATOR
GENERATOR, DRIVE I
COUPLING -
Fiq. 339. — Delco motor-generator installation on Buick showing separate generator and
motor drives.
made for adjusting the chain by an eccentric adjusting ring on the for-
ward end of the starter-generator where its frame extends through the
timing gear housing. By turning the eccentric ring, the starter-generator
can be moved farther away or closer to the engine until the required
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STARTING AND LIGHTING SYSTEMS
277
chain adjustment is obtained. The chain should be adjusted so that it
has an up and down movement of about % in. In the Dyneto system,
similar adjustment may be made by loosening the three screws A and
backing out the adjusting set screw B (not shown in cut) until it forces
the starter away from the engine base and gives the chain the proper
tension.
The Delco motor-generator, Fig. 339, differs from other types in
that it has a generator drive independent of the motor drive. As a
generator, the armature is driven from the front end at 1 or 1^ times
crankshaft speed through an overrunning clutch on the rear end of the
pump shaft, but when operating as a starting motor the rear end of the
armature is connected to the engine through gears meshed with the
5WfCH
COIL
Fiq. 340. — Westinghouse 2-pole square type generator with field winding on one polo.
rim of the flywheel, the cranking gear ratio being usually about 25
to 1. This change in gear ratio is permitted by the slipping of the over-
running clutch in the generator drive end. Another overrunning clutch
is provided in the idler of the motor drive gears, to prevent the flywheel
from driving the armature through the starter drive when the engine
speeds up under its own power.
230. Construction of the Dynamo. — The dynamo is an electric machine
which by the principle of electromagnetic induction may be used for the
conversion of either electrical energy into mechanical energy or mechan-
ical energy into electrical energy. When the dynamo is used for convert-
ing electrical energy into mechanical energy, it is called a motor, and
when it is used for converting mechanical energy into electrical energy it
is called a generator. Likewise, when a dynamo is used both as a genera-
tor and as a motor, such as in the case of the single-unit system on the
automobile, the dynamo is usually termed a motor-generator.
The component parts of the automobile generator are shown in'
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278
THE GASOLINE AUTOMOBILE
Figs. 340, 341, 342, and 343 and consist essentially of an armature, a
field frame, field coils, and brushes. The construction differs materially
from the magneto since the generator operates in conjunction with the
storage battery and must generate direct current. It must also be
designed to permit regulation of the generator output at high engine
Fig. 341. — Westinghouse 4-pole square type generator with field winding on 2 poles.
speeds, which is unnecessary in the magneto used for ignition purposes.
Instead of using permanent magnets for producing the magnetic field
of the generator, the field is produced by electromagnets or "poles"
magnetized by field winding or field coils through which direct current is
ntlD WINDING
DRAWN STEEL FRAME
DRAW* STEEL CfcDfiR4CKET
Fig. 342. — Westinghouse 4-pole round type generator with field winding on each pole.
made to flow. The field frame may be either an iron or steel casting
or it may be made up of a short piece of 4 in. to 6 in. steel tubing in
which poles of soft iron are held in place by machine screws. The frame
may have two, four, or six poles, although the two- and four-pole frames
are the most common. Figure 344 shows several types of dynamo frames
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STARTING AND LIGHTING SYSTEMS
279
most commonly used and the magnetic field circuits in each. It will be
noticed that in some types the field winding is wound on each pole while in
REGULATOR
* CUT OUT
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BEARING
Fio. 343. — Parts of Gray & Davis generator.
Field coils
'
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Fio. 344. — Types of dynamo field frames.
others there is but one field coil to two poles. In the latter case, the manu-
facturer puts more winding in a single field coil instead of distributing it in
smaller coils on all poles. It will also be noticed that in the two-pole
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280
THE GASOLINE AUTOMOBILE
type frame the magnetic field flows directly across the armature, while
in the four- and six-pole types each magnetic circuit cuts through only
a portion of the armature core. For this reason the armature must be
constructed in accordance with the number of field poles, since it is the
cutting of the magnetic field by the winding on the armature in passing
the pole pieces which enables the generator to generate current when
the armature is rotated. The current is collected from the armature
coils by the brushes — usually carbon — which make rubbing contact on
the commutator. The commutator consists of a series of insulated copper
segments mounted on one end of the armature, each segment connecting
to one or more armature coils. The commutator also serves to convert
the alternating current, as generated in the armature coils, into direct
current to make it suitable for battery charging purposes.
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EXTERNAL CIRCUIT
(B)
Fig. 345. — Principle of simple alternating current generator.
231. The Simple Alternating Current Generator. — It has been found
that if a single loop of wire is revolved in the magnetic field between a
North pole and a South pole, there will be an electrical pressure induced
in the two sides of the loop; also, that the voltage and current induced
will be in definite relation to the direction of magnetism and the direction
of rotation. If the terminals of the loop are connected to two metal
collector rings, such as A and B, Fig. 345, upon which brushes rest, this
induced electrical pressure will cause a current to flow through any
external circuit which may be connected across the two brushes.
If the loop be rotated through a complete revolution, sides A and B
will cut magnetic lines of force first in one direction, then in the other,
thereby inducing an alternating voltage across the brushes and causing
an alternating current to flow through the external circuit. As a study
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STARTING AND LIGHTING SYSTEMS
281
of Fig. 345^4 and B will show, the current will make one complete re-
versal in one revolution of the loop. The value of the current during
one complete revolution of the loop may be represented graphically by
the curve shown in Fig. 346, known as the sine curve. The highest and
lowest points of the curve represent the current at its maximum value,
which is reached when the loop is in a horizontal position.
Fio. 346. — Current wave from simple alternating current generator.
232. The Simple Direct-current Generator. — The alternating current
produced in the loop may be converted into direct current in the external
circuit by replacing the two collector rings with a simple two-segment
commutator, as shown in Fig. 347. The two segments of the commutator
are connected to the two ends of the loop but insulated from each other.
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EXTERNAL CIRCUIT
(B)
Fio. 347. — Principle of simple direct-current generator.
The only connection between the commutator segments besides through
the armature loop is through the brushes and the external circuit. The
brushes remain stationary and make rubbing contact first with one
segment and then with the other, as the commutator and loop rotate as
a unit. With this arrangement it will be noted that as fast as the loop
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282
THE GASOLINE AUTOMOBILE
turns over and as fast as the induced voltage reverses in the loop, the
segments change connection with the brushes and the current is made to
flow each time through the external circuit in the same direction. The
current thus obtained is direct current and may be graphically represented
as in Fig. 348. Comparing Fig. 348 with Fig. 346, it will be noted that
the chief accomplishment has been to direct both impulses of current in
the same direction.
-ONE REVOLUTION
CYCLt
Fig. 348. — Current wave from simple direct-current generator.
Such a direct-current generator, constructed with an armature of
a single winding of one or more turns, would be very inefficient and un«-
satisfactory in that the current would pulsate in value. To overcome
this trouble, the armature core, which is in the form of a laminated iron
cylinder, is wound with a great many coils equally spaced around its
c _
BATTERY
Fia. 349. — Principle of the direct-current motor.
circumference, each coil being connected to segments in the commutator.
These coils are connected so that the current impulse of one coil overlaps
the current impulse of the next, much the same as the overlapping of
the power impulses in an 8- or 12-cylinder engine. The result is practically
a continuous steady flow of current.
233. The Simple Direct-current Motor. — A direct-current motor is a
dynamo which will run as a motor on direct current. If the brushes of
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STARTING AND LIGHTING SYSTEMS
283
the simple generator shown in Fig. 347 are connected to a battery and
current permitted to flow through the loop of wire as shown in Fig. 349,
the loop of wire will rotate as a motor in the direction indicated by the
arrow. Briefly, the cause of this rotation may be explained as being due
to the repulsion between the field magnetism and the magnetic field (set
up around the loop of wire) produced by the current flowing in the wire.
In Fig. 350 is shown a simple experiment from which may be readily
a
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S 1
\vli'w^0IRECT,ON
Vn VflVn ! pulsion
DIRECTION OF
WIRE
REPULSION
iCONOUCTOR
HORSESHOE MA6NET
DRY CELLS
Fiq. 350. — Experiment showing the relation between direction of magnetism, direction of
current, and the direction of wire.
determined the direction of this repulsion in relation to the direction
of current and magnetism. If the magnet is placed so that the North
(N) pole is above the wire (W) and current is sent through the loop of
wire, in at E and out at F as shown, the wire will be repulsed to the posi-
tion Wi. The repulsion is caused by all of the magnetic lines of force
tending to flow around the conductor in the same direction and the con-
sequent distortion and crowding of the magnetic lines on one side of the
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284
THE GASOLINE AUTOMOBILE
conductor more than on the other. This results in a repulsion of the con-
ductor as shown in Fig. 3502?. On the other hand, if the magnet is
reversed, thus reversing the magnetism, but the direction of current is
unchanged, the magnetic lines of force will crowd to the other side of the
conductor and it will be repelled in the opposite direction as shown in
Fig. 350C and the wire will be repulsed to the position W2, Fig. 350A.
The same action would result if the current were reversed instead of the
magnetism. Thus, in Fig. 349-4., owing to the current flowing in the
two sides of the loop A and B in reverse directions and the consequent
field distortion as shown in Fig. 349J5, A will be repulsed upward and
B downward and the loop will rotate m a clockwise direction.
Fig. 351. — Parts of Westinghousc starting motor, mechanical pinion shift type.
In practice, such as in the starting motor shown in Fig. 351, the motor
armature has many armature coils equally spaced around the entire
circumference of the armature core, each of which carries current and,
consequently, exerts a force to rotate the armature as it passes the pole
pieces. The result is a comparatively high turning power or torque which
if applied through suitable gear reduction is sufficient to crank the engine.
234. The Shunt-wound Generator. — In all generators and motors
now used as standard equipment on the automobile, the magnetic field
is produced by a field winding of either the shunt or series type, or a com-
bination of the two. The shunt type of field winding is particularly
adapted to the generator, while the series type is especially adapted to
the starting motor.
In the shunt-wound generator, the field winding is connected across
the brushes of the generator as in Fig. 352, so that about 8 to 12 per cent,
of the total current generated by the armature is shunted through the
field coils for producing the field magnetism. In the series type of wind-
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STARTING AND LIGHTING SYSTEMS
285
ing, Fig. 353, all the current which flows through the armature must also
flow through the field winding.
If a generator field frame should be tested with a magnetic compass it
will be found that the frame will show North and South magnetic polarity
FRAME
MAIN GENERATOR
LEADS CONNECTED
TO BATTERY AND
LIGHTING
SYSTEM
3HUNT FIELD
WINDING
Fio. 352. — Principle of shunt-wound generator.
at the pole pieces, even with the generator dismantled. This magnetism
is known as residual magnetism. It is simply the magnetism which
remains in the pole pieces and frame after the field magnetizing current
has died out. The direction of
this magnetism will always be in
the same direction as the field
through the poles, when they
were last magnetized. Thus the
generator frame may be given
residual magnetism by simply
sending direct current through
the shunt field winding from
either a storage battery, or a set
of dry cells. The residual mag-
netism may be reversed by re-
versing the direction of the
magnetizing current.
In Pig. 352, which represents
a shunt-wound generator, one armature coil only, of the simplest type, is
shown, although the armature may be considered as being wound full of
similar coils distributed at equal intervals around the armature, each coil
being connected to the commutator the same as the one shown. Such
an armature is called a drum wound, open-circuited, 2-pole type arma-
ture. The open-circuited type armature, however, is no longer used
for automobile generators, having been replaced by the closed-circuit
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286 THE GASOLINE AUTOMOBILE
type. The principle of operation, however, is the same and much more
easily understood.
The principle of operation of a shunt-wound generator is as follows:
In Fig. 352 let it be assumed that the armature rotates in a clockwise
direction as indicated by the arrow, and that (n) and (s), marked on the
pole pieces, represent the direction of residual magnetism which is across
the armature from left to right. When the armature is rotated, the
armature coils, cutting the weak magnetic field produced by the residual
magnetism, will set up a slight voltage across the brushes, usually 1 to
13^ volts, making the upper brush positive and the lower brush negative.
This voltage is sufficient to overcome the resistance in the shunt-field
winding connected across the two brushes, thereby causing a current to
flow from the positive (+) brush through the field winding around the
pole pieces to the negative (— ) brush. If the magnetic effect of this
field current is in the same direction as the residual magnetism (as in our
example) the pole strength will be increased and tliis in turn will increase
the magnetic flux through the armature. Since the armature coils will
then be permitted to cut more magnetic lines of force per revolution,
the voltage across the brushes will also be increased. An increase in
brush voltage increases the field strength which in turn increases arma-
ture output. Thus the armature voltage helps the field and the field
helps the armature voltage until the generator reaches its normal
operating voltage. This process, which all automobile generators
must go through in producing a voltage, is called the "building up" of
the generator.
235. Conditions Which Prevent a Generator from Building Up. —
From the foregoing it will be noted that several conditions are necessary
to permit the generator to build up a voltage. Two of the most im-
portant requirements are that the field frame have residual magnetism
as a foundation on which to build, and that the direction of the current
in each field coil be in such direction around the pole that the field current
will produce magnetism to assist this residual magnetism. Otherwise,
the voltage cannot build up higher than that produced by the residual
magnetism. Other common conditions which prevent the generator
from building up are:
1. Reversed direction of armature rotation.
2. Open in shunt field circuit due to: blown fuse, broken wire, loose
connection, etc.
3. Heavy short circuit across the main brushes.
4. Brushes worn, broken, or sticking in their holders.
5. Weak spring tension on brushes.
6. Dirty commutator or high mica preventing the brushes making
proper contact.
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STARTING AND LIGHTING SYSTEMS
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7. Short-circuited, open, or grounded field coils.
8. Short-circuited, open, or grounded armature coils.
9. Field coils opposed on two pole generator.
10. Brushes in wrong position on the commutator.
236. Types of Field Winding. — Various methods may be used in
winding the field poles of a dynamo to suit the purpose for which it is
SHUNT WOUND DTMAMO
IB) SERIES WOUNO DYNAMO
E«tE5 FltLD,
tjl SHUNT riCLo\
(C) cumVlative compound wound
DYIfftMO WITH SHORT SHUNT
(D) CUMULATIVE COMPOUND WOUND
DYNAMO WITH LOW6 SHUNT
\^riO
(D DIFFERENTIAL COMPOUND WOUND
DYNAMO WITH SHORT SHUNT
(F) DIFFERENTIAL COMPOUND WOUND
DYNAMO WITH LONG SHUNT
Fig. 354. — Types of dynamo field windings.
to be used. Figure 354 shows the different ways in which the shunt and
series field may be connected on the same type of frame, the markings
and arrows referring in each case to the dynamo when operating as a
generator. These markings do not represent the conditions when current
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288 THE GASOLINE AUTOMOBILE
is sent through the machine causing the dynamo to operate as a motor.
The small diagram to the right of each main sketch is the conventional
way of" indicating briefly that particular type of D. C. dynamo. By
applying the right-hand rule for determining the magnetic polarity of
an electromagnet (as given in Chapter VI) it will be seen that in Fig. 354,
C and D, the shunt and series winding, create magnetism in the same
direction, while in E and F the magnetism produced by a current flowing
in the series field winding will oppose that produced by the shunt winding.
When a shunt and series winding operate to create magnetism in the
same direction they are said to be cumulative wound, and when they
operate to oppose each other they are said to be differentially wound.
The shunt field may be connected either inside or outside of the series
field winding. When it is connected inside, as in C and E, it is known
as a short shunt connection, and when it is connected outside the series
as in D and Ff it is known as a long shunt connection. The principle
of each is very similar, the difference being that in the long shunt con-
nection the shunt-field current must pass through both the shunt and
series field coils to complete its circuit.
In practice, types C and D are not used on the automobile, owing
to the fact that any increase in armature speed and output would increase
the field strength, causing an overloading of the generator. The simple
shunt type of winding used in conjunction with a suitable regulator is
the type of field winding chiefly used for the generator, while the series
type of winding is used in the starting motor, owing to the fact that all
the current through the armature must flow through the field winding
thus giving the motor the greatest possible cranking power. Types
E and F are used in both generators and motor-generators. This type
of winding is particularly adapted for motor-generators since the windings
operate differentially, the series bucking the shunt, for regulating pur-
poses when operating as a generator, and cumulative, the series helping
the shunt, when current is sent through the machine in the reverse direc-
tion when operating as a starting motor. This action is possible, due to
the fact that the current will reverse in the series winding and not in
the shunt winding, if the current is reversed through the dynamo, as a
study of the figures will show. In a generator of the differential wound
type, the series winding, which is commonly known as reverse series or
bucking series, is used only for regulating purposes, the shunt winding
being the prevailing winding and controlling the direction of magnetism.
The shunt winding is distinguished from the series winding since it con-
sists of a large number of turns of comparatively small wire, while the
series winding consists of a comparatively few turns of large wire.- Both
windings are well insulated and in some cases impregnated with a spe-
cial compound to make them water and oil proof.
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STARTING AND LIGHTING SYSTEMS
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237. The Reverse Current Cut-out — The reverse current relay or
cutout is an automatic electromagnetic switch connected in the battery
charging circuit between the generator and the storage battery of the
electric system. Its function is to connect automatically the generator
to the battery when the voltage of the generator is sufficient to charge
the battery and to disconnect the two when the generator is not running
or when its voltage falls below that of the battery to prevent the battery
discharging through the generator windings. In these respects the action
of the cut-out is very similar to that of the check valve connected between
the pump and the reservoir as shown in Fig. 324.
A circuit diagram of a typical cut-out is shown in Fig. 355, in which it
is shown connected with a differentially wound generator and a 6-volt
storage battery. As will be noted from the diagram, tjie cut-out con-
WEVERSE CURRENT CUT-gUT
\ CUT* OUT ■fWM* cu-juouti
cuwuntcou. c?2IfCTy ^Snmt^et
(Hf AVY WINPNM) *■**> f s'
LI4HTIM4
'•WITCH
U6HTIN6
SYSTEM
LAMPS
SHUNT FIELD
WINOMMi
-*•«*-
TSR.
Fio. 355. — Wiring diagram of a typical reverse current cut-out.
8ist8 of an iron core, a fine shunt winding known as a voltage coil, a heavy
series winding known as a current coil, and a set of contacts. One of the con-
tacts is carried on one end of an iron contact arm that is mounted close to
but held apart from the core, by spring tension. The contact points are
thus held normally open and are closed only when the magnetic pull of
the core on the contact arm is sufficient to overcome the tension of the
spring. The spring is adjusted so that the contacts will close when the
voltage of the generator has reached from 6H to 7 volts in a 6-volt system
or 13 to 14 volts in a 12-volt system. These voltages are usually at-
tained, causing the cut-out to close at a car speed of from 8 to 10 miles
per hour on direct drive.
The voltage coil, which consists of many turns of a fine winding, is con-
nected across the generator terminals so as to receive the full voltage of
the generator. When the generator attains a speed at which it develops
19
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290 THE GASOLINE AUTOMOBILE
approximately 7 volts the core is sufficiently magnetized to overcome
the spring tension and to close the cut-out contacts. This completes
the circuit between the generator and the battery. Since the voltage
of the generator at this time is higher than the voltage of the battery a
charging current will flow from the positive (+) terminal of the genera-
tor, through the current coil and contacts of the cut-out, through the
cells of the battery from positive (+) to negative (— ) returning through
the ground to the negative terminal of the generator. It will be noticed
that the charging current flowing through the current coil flows around
the core and creates a magnetic effect in the core in the same direction
as that produced by the voltage coil. This greatly increases the mag-
netic pull on the contact arm and holds the contacts firmly closed.
When the speed of the generator is decreased to a value at which its
voltage is lower than that of the battery, that is, below 6 volts, or when
the generator is at rest, a momentary discharge of the battery through
the current coil takes place in the reverse direction to the voltage coil
and the core is demagnetized. The instant the core demagnetizes, the
spring, which is under tension, pulls the contact arm away from the core
and opens the circuit. The cut-out should be adjusted to open when the
discharge current, as indicated by the ammeter, is between zero and 2
amperes, preferably as near zero as possible to prevent flashing of the
contact points.
The ammeter is usually connected as shown so that it will register
the amount of current either charging or discharging from the battery.
The car speed at which the cut-out opens should be 2 to 3 miles per hour
below tjie closing speed. These speeds may be determined by increasing
and decreasing the speed of the car gradually and noting the readings
of the speedometer when the ammeter first shows charge and again when
it returns to zero. Another method of determining whether the cut-out
is closing properly, if the car is not running, is to start the engine, turn
on the headlights, and watch the brilliancy of the headlights as the engine
is gradually increased in speed.- In most cases, as soon as the engine
reaches a speed of 600 to 800 revolutions per minute (corresponding to
a driving speed of 8 to 10 M.P.H.), it will be noticed that the lights
brighten up. This sudden increase in brilliancy will occur at the instant
the cut-out closes and is due to the increased voltage impressed across the
lamps, namely, from 7 to 7)4 volts instead of 6 volts when the generator
is connected to the battery and the lamp circuit.
238. Regulation of the Generator. — Owing to the fact that all genera-
tors used on the automobile have the characteristic of increasing in
voltage and current output with increase in engine speed, some method
of generator regulation is necessary to protect the generator windings
and brushes against excessive current* overload and the battery from
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STARTING AND LIGHTING SYSTEMS 291
overcharge. Several methods of regulation are possible such as: (1)
controlling the speed of the armature through mechanical governors,
(2) controlling the strength of the field current which in turn controls
the strength of the field magnetism cut by the armature windings, and
(3) controlling the current output by a mechanically operated rheostat
(adjustable resistance unit) placed in series with the battery, the resist-
ance of the battery charging circuit being increased or decreased as the
armature speed increases or decreases. The first and third methods have
not proved satisfactory so that the various methods of regulation now
in use all operate on the principle of controlling the field magnetism —
decreasing the field strength as the armature speed increases, thus striv-
ing to hold the generator output constant.
Regulation of the field magnetism may be effected in three principal
ways:
1. Through reverse series (differential) field winding in which a series
winding opposes the shunt winding more and more as the generator speed
and output increase.
2. A vibrating type relay in which a resistance unit is cut in and out
of the shunt-field circuit to obtain either current or voltage regulation,
or both.
3. The third brush principle of regulation, which depends upon the
reactions that take place in the armature and the resulting distortion
of the path of field magnetism through the armature, as the generator
increases in speed and current output. '
239. Generator Regulation through Reverse Series Field Winding.
—The reverse series or bucking field method of generator regulation is
one of the simplest methods in use from the standpoint of construction
and operation. It is simple, in view of the fact that the regulation is
taken care of by the inherent action of the field winding which does not
involve any wearing or moving parts, and requires no adjustment. Two
typical methods of connecting the shunt and series field windings to
obtain this regulation were shown in Fig. 354J? and F, Fig. 3542? showing
the short shunt and Fig. 354^ showing the long shunt method of connect-
ing the windings. The principle of each, however, is very similar, the
difference being that in the long shunt connection the shunt-field current
must pass through both the shunt and series field coils to complete its
circuit.
A typical application of the reverse series method of generator regu-
lation is found in the Auto-Lite two-pole laminated frame type generator
Bhown in Fig. 356. From the diagram, Fig. 357, it will be noted that the
field winding is of the long shunt type in that one end of the shunt wind-
ing is connected at the outer end of the series. The circuits of the cut-
out relay will be found similar to those described for Fig. 355.
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292
THE GASOLINE AUTOMOBILE
Referring to Fig. 357, the principle of operation is as follows: As the
generator builds up a voltage, two circuits are established between the
brushes, one through the shunt field winding, magnetizing the field frame
North and South as shown, the other through the voltage coil winding of
the cut-out relay. Both of these cir-
cuits lead through the series field
winding and complete their circuits
as indicated by the arrows in the
diagram. At the speed at which the
cut-out closes, connecting the genera-
tor with the battery, the generator
voltage is only slightly above that of
the battery and a small current will
flow through the battery in the charg-
ing direction. The path of this cur-
rent is from the positive (+) brush
through the reverse series field wind-
ing, over the cut-out contacts through
the current coil, through the ammeter and battery from positive (+) to
negative ( — ) returning through the ground to the negative ( — ) brush
of the generator. As this charging current flows through the reverse
series fieM winding in a reverse direction to the current flowing in the
Fig. 366. — Auto-lite generator,
Model G.
JUMOTION OF
SHUNT AND
SERIES FIELD
WINDING*
GENERATOR
CUT-OUT RELAY
(mounted either on 6ene**tor
FRAME OR ON DASH. AOJU5TCO
TO CLOSE AT &£ TO 7 VOLTS)
Fio. 357. — Circuit diagram of auto-lite generator and cut-out relay showing reverse
series field method of generator regulation.
shunt winding, a demagnetizing force is produced in the field frame
which increases with increase in generator speed and current output to
the battery. The result is a weakening of the field magnetism as the
armature speed increases, so that, after the maximum desired charging
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STARTING AND LIGHTING SYSTEMS 293
rate is reached, which is usually 12 to 14 amperes at 18 to 20 miles per
hour, the current output of the generator will never exceed the predeter-
mined amount even though the generator is driven at a very high rate
of speed.
It will be noted that the regulation depends upon the current flow-
ing in the reverse series winding. Consequently, since this regulating
current constitutes the current supplied by the generator to the battery
and the lighting system (in case the lights should be turned on), it is very
essential that an open-circuit does not occur in the battery charging cir-
cuit, otherwise the charging current will be obstructed and the regulation
of the generator destroyed. Precautions, therefore, must be taken*8t all
times to see that: the cut-out closes properly; the connections of the gen-
erator, cut-out, and ammeter are clean and tight; and that the battery
terminals are always tight and free from corrosion. If such an open-
circuit should occur in the charging circuit destroying generator regu-
lation, the voltage will become excessive, usually resulting in damage to
the field and armature winding, also the winding of the cut-out. In case
the open in the circuit exists at either of the battery terminals, the lights
may also be burned out if they were turned on with the generator run-
ning at speed above 15 to 18 miles per hour or above the speed at which
regulation should begin. If for any reason the car is to be operated with
the battery disconnected, the system should be protected by connecting
a piece of copper wire across the two generator terminals. This short- *
circuits the brushes through the reverse series winding and prevents the
generator from building up a voltage.
240. Current Regulation of the Generator through Vibrating Type
Relay. — A circuit diagram of a typical vibrating type regulator used for
obtaining constant current regulation of the generator is shown in Fig.
358. As may be seen from the diagram, the regulating relay consists
of a soft iron core, around which is wound a single winding; a current
coil of heavy wire; a set of regulator contact points, held normally closed
by spring tension; and a resistance unit, which is connected across the
two regulator contact points.
The purpose of this regulating relay is to control the current output
of the generator, as the generator speed increases, by means of cutting a
resistance intermittently in and out of the shunt-field circuit as the regu-
lator points open and close, due to the varying magnetic pull of the core.
The resistance unit is connected in the shunt-field circuit but is normally
short-circuited by the regulator contacts, one of which is mounted on a
soft iron contact arm to which is attached the spring for holding the points
in contact. When driven by the engine, the generator builds up as a
simple shunt-wound generator, the shunt-field current flowing as indicated
from the positive (+) brush through the contact points, through the
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294
THE GASOLINE AUTOMOBILE
field winding to the negative (— ) brush. When the speed and voltage
of the generator are sufficiently increased. to cause the cut-out to close,
thus completing the battery charging circuit, the generator will begin
to charge the battery, the charging current flowing through the regulator
winding. This current flowing through the regulator winding will mag-
netize the core which in turn exerts a magnetic pull on the regulator con-
tact arm tending to pull the contacts apart. When this current — the
armature current — becomes a certain amount (usually in practice 10
amperes) the core becomes sufficiently magnetized to attract the contact
arm, overcoming the pull of the regulator spring. This separates the
contact points, and the resistance unit is inserted in series with the shunt-
field winding causing the field strength to weaken. This causes the
armature voltage to drop and, consequently, the charging current to
decrease. When the current decreases to a predetermined amount (say
CUTOUT RELAY
/
GENERATOR
REGULATING RELAY
/
NCSISURCt £j ft
REGULATOR
CONTACT POINTS
(contact* nomhauy clomo
eoi VWUfTC AT If TOItKtK
ON WHEN CMAMM6 CtMMHT
IMS (CACHED 10 TO * AMM)
SHUHT FltLO WINOmtt
GftOUNO" ClRCUtT'THlir HUY1C
Fio. 358. — Circuit diagram of typical vibrating type regulator to obtain constant current
regulation of the generator.
9 amperes) the current coil does not magnetize the core sufficiently to
overcome the pull of the spring, thus allowing the spring to close the con-
tacts. With the contacts closed, the resistance unit is once more short-
circuited and the full field strength is restored, causing the charging
current to again increase. Under operating condition, the contact arm
vibrates automatically and rapidly at such a rate as to keep the generator
output constant.
As a result, the generator will never charge the battery above a
predetermined amount (10 amperes) no matter how high the speed of
the car, but at all speeds greater than a predetermined speed (about 15
miles per hour in practice) the generator will produce a substantially
constant current. This will be true regardless of whether the battery
is fully charged or completely discharged.
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STARTING AND LIGHTING SYSTEMS
295
Such a method of generator regulation is termed current regulation
since the current output of the generator is made use of in regulating
itself. It is, therefore, very important that no opens occur in the charging
circuit, since there would then be no current flowing through the current
coil to operate the vibrating points and all regulation of the generator
would be destroyed. Consequently, to operate a car equipped with this
type system with the battery disconnected the field wire should be dis-
connected, thereby preventing the generator from building up a voltage.
As in the case of all systems controlled by a vibrating type relay, the
charging rate of the generator is very easily adjusted. To increase the
maximum charging rate, the spring tension should be increased slightly,
and to decrease the maximum charging rate, the spring tension should
be decreased, caution being taken that the generator does not become
overloaded. Adjustments should be made only by a competent mechanic
who is experienced in starting and lighting repairing.
CUTOUTRELAY
U6HT1N6
^rrr^M^. SYSTEM
. - l-OUT POIHT5 r-f»j
>0*MAU.Y own) t VJ^
GENERATOR
Fig.
359. — Circuit diagram of typical vibrating type regulator to obtain constant voltage
regulation of the generator.
241. Voltage Regulation of the Generator through Vibrating Type
Relay. — A circuit diagram of a typical vibrating type regulator to obtain
constant voltage regulation of the generator is shown in Fig. 359. Al-
though the construction of the relay does not differ widely from that of
the current type regulator, as the diagram shows, the principle is some-
what different in that in this system the voltage of the generator is auto-
matically regulated instead of its current output, as with the current
type regulator. As may be seen in comparing Fig. 358 with Fig. 359,
the principal difference in the two relays is in the winding of the core.
In the voltage-type regulator the charging current does not flow through
the regulator winding. The winding of the core consists of a voltage
coil of fine wire, the two ends of which are connected across the generator
brushes and in parallel with the battery instead of in series with it as in
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296 THE GASOLINE AUTOMOBILE
the case of the current-type regulator. The core, regulator points, and
resistance unit, however, are practically the same.
The current flowing in the voltage coil and the resulting magnetic
pull of the core on the regulator contact points will depend upon the
voltage developed by the generator. In the case of a 6-volt system the
regulator is usually adjusted to hold the generator voltage constant at
7.75 volts. With increasing generator speed the voltage will tend to rise
above 7.75. If, however, this value is exceeded by a very small amount,
the increased magnetic pull of the core on the contact arm, due to current
flowing in the voltage coil, will overcome the spring pull and the contact
arm will be drawn toward the core, thus opening the contacts and
inserting the resistance in the generator field circuit. The added resist-
ance in the field circuit decreases the current in the field winding, and the
voltage developed by the armature tends to drop below the normal value
of 7.75 volts.
If the voltage drops slightly below the normal, the pull of the spring
on the regulator contact arm predominates and the arm moves away
from the core and closes the contacts which short-circuits the resistance
unit and permits the field current to increase. This cycle of operation
is repeated rapidly and maintains the generator voltage constant at all
speeds above the critical value at which it develops 7.75 volts with the
resistance cut-out of the field circuit. In this type system it is possible
to operate the lamps off of the generator with the battery disconnected
without danger of burning out the bulbs, since the generator is regulated
to maintain a constant voltage even though an open should occur in the
charging circuit.
It is obvious that increasing the tension of the regulator spring will
increase the constant voltage which the generator will maintain. Under
no circumstances should the regulator spring tension be increased in an
attempt to have the generator charge at a higher rate at low speed. The
generator cannot begin to charge until the cut-out closes, and the closing
of the cut-out is independent of the action of the regulator. The cut-out
closes after the generator reaches a speed at which it develops 6.5 to 7
volts, and no adjustment of the regulator or cut-out can change the speed
characteristics of the generator. Increasing the tension of the regulator
spring so that the generator will develop a constant voltage in excess of
7.75 volts will result in excessive current to the battery, overcharging
it or causing the generator to overheat with the possibility of burning
it out.
Characteristics of Voltage Regulation. — With the constant voltage-type
generator the amount of current generated depends upon the state of
charge of the storage battery and the amount of lamp load in use. After
the generator reaches a speed at which it develops its normal voltage,
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STARTING AND LIGHTING SYSTEMS 297
there will be no further increase in voltage with increasing speed; the
voltage will be maintained constant at all loads, and at all higher speeds.
The voltage, measured across the terminals of the storage battery, is
variable and depends upon the state of charge of the battery. With a
discharged battery the voltage is a minimum, and the voltage increases
in value as the charge proceeds.
During the time the generator is connected to the battery, the dif-
ference in pressure between the two is the pressure available for sending
current into the battery; thus, if the battery voltage is 6.2 and the genera-
tor voltage 7.75, the pressure available for sending current through the
battery will be 1.55 volts. In the case of a discharged battery, the dif-
ference in pressure between the generator and battery will be relatively
great so that a comparatively high charging current will pass from the
generator to the battery. As the charge proceeds the voltage of the
battery increases so that the difference in pressure between generator
and battery is continually diminishing. With a fully charged battery
its pressure is very nearly equal to that of the generator, and the difference
between the two is small. As this small difference in pressure is all that
is available for sending current into the battery, the charging current
will be small. The current generated, therefore, is variable and is inde-
pendent of speed. The charging current tapers from a maximum in
practice, usually 15 to 20 amperes to a discharged battery, to a minimum
usually 4 to 6 amperes in the case of a fully charged battery.
242. Combined Current and Voltage Regulation of the Generator
through Vibrating Type Relay. — The circuit diagram of a typical vibrat-
ing type relay for the purpose of obtaining both constant current and
voltage regulation of the generator, is shown in Fig. 360. As will be read-
ily seen in comparing this diagram with the two regulator diagrams shown
in Fig. 358 and Fig. 359, the winding of the relay is merely a combination
of the other two, the core being wound with both a current and a voltage
winding. This construction permits of the combining of the cut-out
and regulator into a single relay. As shown, the cut-out points are
mounted on one end of the core, while the regulating points are mounted
on the other end, the two sets of contacts being operated by independent
springs.
The operation of the regulating part of this relay is practically the
same as that of the voltage-type regulator with the exception that in
addition to the controlling of the generator voltage, as effected by the
voltage winding, the generator current output is also controlled by the
charging current flowing through the current coil. It will be noted from
the diagram that both windings carry current around the core in the same
direction, and the magnetizing force of both assist each other in operating
both the regulator and the cut-out contact points.
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298
THE GASOLINE AUTOMOBILE
By combining the current and voltage windings in this manner,
combined characteristics of both the constant current and constant volt-
age methods of regulation are partly attained. Proper functioning of the
relay, however, depends upon the combined effect of both windings;
consequently, if for any reason the cut-out points do not close to make
proper contact, or an open should occur at some other point in the charg-
ing circuit, such as due to a burned out ammeter or corroded battery
terminal, no current will flow through the current coil, thus leaving the
generator to depend entirely on the voltage winding for regulation. The
generator voltage will, in this event, operate somewhat higher than normal
when the car is driven at high speeds and if continued may cause damage
to the regulator and generator windings. On the other hand, if the
voltage winding should become broken or disconnected, the cut-out
COMBINED REGULATOR
AND CUT-OUT RELAY
GENERATOR
CIMCUIT TMHU PftAMe
rant
Fig. 360. — Circuit diagram of typical combination vibrating type regulator and out-out
to obtain constant current and voltage. regulation of the generator.
cannot close and entire regulation of the generator is destroyed. Pre-
cautions should be taken, therefore, to prevent such opens occurring in
both the voltage coil and charging circuits, otherwise possible damage
may result through burning out of the generator and regulator windings.
As a safeguard in case the car is to be operated with the storage battery
removed, the shunt field wire connection to the regulator should be disn
connected, thereby preventing the generator from building up. In
many installations, the regulator is mounted on top of the generator
frame in which event it is often more convenient to remove the entire
regulator during the period which the battery is disconnected and replace
it when the battery is again installed.
243. The Ward Leonard Automatic Controller. — The Ward Leonard
automatic controller type CC, Fig. 361, is a typical vibrating type regu-
lator and cut-out by which both the voltage and current output of the
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STARTING AND LIGHTING SYSTEMS
299
generator are controlled. The wiring diagram of the controller is shown
in Fig. 362. The voltage coil winding is represented by N, the current
coil by F, the cut-out contact by D, the regulator contact by E, and the
resistance unit by M .
Fig. 361. — Ward Leonard automatic controller, Type CC.
When the generator is driven at a speed sufficient to close the cut-out
and charge the battery, the current output of the generator passes
through the current coil F. This is in the same direction around the
core as the current flowing in the voltage winding. When the charging
GENERATOR -=
Fig. 362. — Wiring diagram of Ward Leonard controller, Typo CC.
rate reaches 10 amperes, the magnetic pull of the core is sufficient to
attract the arm H and separate the regulator contacts EE} thereby in-
serting the resistance M in series with the shunt field. This weakens the
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300 THE GASOLINE AUTOMOBILE
field and reduces the generator voltage and current output. When the
current decreases to, say 9 amperes, the coil F is not strong enough to
hold the arm H against the action of the spring J and the contact at E
is made again, short-circuiting the resistance M. This increases the
field strength and the generator output tends to increase, but when it
is increased to 10 amperes the contacts E open again, inserting the re-
sistance M. This same cycle of operations of inserting and short-cir-
cuiting the resistance M keeps occurring as the generator speed is in-
creased. Under operating conditions, the arm H vibrates automatically
and rapidly at such a rate as to keep the voltage and current output of
the generator constant when the engine is running at a fair speed.
244. Third Brush Regulation. — The intermediate or third brush
principle of generator regulation depends entirely for its operation upon
the reactions which exist in the armature when it is rotated and generates
a current. Consequently, in order to understand the principle of third
brush regulation, the causes of these armature reactions must first be
thoroughly understood.
It has been found that when the armature is made to rotate between
the pole pieces, causing the various armature coils to cut the magnetic
lines of force, the side of each armature loop which cuts in front of the
North pole will induce a voltage in one direction, while the opposite side
of the same loop cutting in front of the South pole will induce a voltage
in the opposite direction with respect to the armature and pole pieces.
In Fig. 363 let the small circles (shown equally spaced around the cir-
cumference of the armature) represent so many armature coils, each
coil being connected to the commutator segments in such a way that when
the armature is rotated in the clockwise direction the upper brush will
become positive (+) and the lower brush negative ( — ) polarity. With
the armature rotating in this direction, the current induced in each coil
as it passes in front of the North pole will be generated to flow in or away
from the reader, while, in front of the South pole, the current will be gener-
ated to flow out or toward the reader. The direction of the current
flowing in each coil generating is indicated by either a cross (+) or a dot
(.), depending upon whether the current is leading away from or toward
the reader. The cross and dot represent the tail and point, respectively,
of an arrow pointing in the direction of current and should not be confused
with the plus (+) and minus ( — ) signs representing positive and negative
polarity.
When the armature is delivering current to an external circuit, such
as the battery and lighting system, the effect of the current flowing in
different general directions in the armature coils on opposite sides of the
armature, will be to magnetize the armature in a cross direction, thus
making one side of the armature core north and the other south. This
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STARTING AND LIGHTING SYSTEMS
301
effect is much the same as if a wire were wound on an iron cylinder and a
current passed through it as shown in Fig. 364A. In the armature, this
cross magnetizing force will be through the armature and pole pieces at
right angles to the magnetic field produced by the field winding as shown
Fio. 363. — Distribution of magnetic flux through generator armature at low speed.
in Fig. 3642?. By a study of thi3 figure it will be seen that at the lower
corner «of the north pole piece and at the upper corner of the south pole
piece the magnetic lines of the two fields are in opposite direction, while
at the upper corner of the north pole piece and at the lower south pole
piece the magnetic lines are in the same direction. This will cause a
N
IB)
Fig. 364. — Cross magnetisation of generator armature due to generated current.
reaction between the two magnetic fields resulting in the magnetic lines
being crowded to the trailing corners of the poles, thus distorting the
general path of the magnetic flux across the armature as shown in Fig.
365. The amount of this field distortion will depend upon the speed of
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302
THE GASOLINE AUTOMOBILE
the armature and the strength of the current — the battery charqpng and
lighting current — flowing in the armature winding. Owing to the shift-
ing of the magnetic flux and the consequent shifting of the points of
maximum voltage on the commutator, the brushes should be set slightly
Fig. 365. — Distortion of magnetic flux through generator armature due to speed of rota-
tion and armature current.
ahead, as shown, to have them in the best running position at the normal
operating speeds of the armature.
Principle of Third Brush Regulation. — The wiring and arrangement
of brushes for a typical 2-pole third brush type generator are shown in
THIRD BRUSH
SHUNT FIELD
WINDING
TO STORAGE BATTERY
AND LIGHTING
SYSTEM
MAIN BRUSH
GR
Fiq. 366. — Diagram showing principle of third brush regulation.
Fig. 366. A and B represent the main brushes which connect to the
storage battery and lighting system, and C the third brush, which con-
nects only to one end of the shunt-field winding. The dotted loops con-
necting the commutator segments represent the various armature coils
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STARTING AND LIGHTING SYSTEMS 303
(which are also represented by the circles), while the arrow on each loop
indicates the direction of the induced current in the loop.
When the generator is running at low speed and little or no current
is flowing in the armature winding, the magnetic field produced by the
field winding is approximately straight through the armature from one
pole piece to the other, and the voltage generated by each armature coil
is practically uniform during the time the coil is under the pole pieces.
In a generator of the 6-volt type, in which 7 to 7% volts are actually
generated between the main brushes when charging the battery, it is
evident that with the third brush in the position shown, approximately
5 volts would be generated between B and the third brush Cf since these
brushes span only this relative proportion of the commutator segments
and, consequently, collect only a part of the total voltage generated. In
respect to B, the third brush C is of positive polarity, so that if one end
of the shunt-field winding is connected to C and the other end to B, the
field current will flow from C through the winding to B as indicated
by the arrows, the voltage being approximately 5 volts when the full
voltage is 7.
As the generator speed and charging rate increase, the charging
current flowing through the armature winding produces a cross-magnetic
field in the direction of the arrow G. This distorts the magnetic field *
produced by the shunt-field winding, so that instead of the magnetism
being equally distributed under the pole pieces, it becomes denser in the
pole tips marked D and E and weaker in the other pole tips. With this
distortion of the magnetic field, the armature coils no longer generate an
equal voltage while passing under the different parts of the pole. Al-
though the voltage across the main brushes A and B remains near 7 to 7^
volts, the greater part of this voltage is generated by the coils which
connect to the commutator between brushes C and Af as these coils are
cutting the denser magnetic field and the coils which connect to the
commutator between the brushes B and C are for the most of the time
in the region of the weak field, thus generating a lower voltage. The
result is a dropping off of the voltage across brushes B and C as the speed
and charging rate increase. Since the voltage of these brushes is the
same as that applied to the shunt-field winding, it is apparent that the
field strength is weakened. As this drop in field voltage takes place more
and more as the speed of the generator increases, the result will be an
automatic regulation of the current output.
Adjusting Charging Rate. — In most generators having third brush
regulation, provision is made for changing the maximum charging rate
to suit the conditions under which the generator is operated. This
can be accomplished by moving the position of the third brush on the
commutator. Moving this brush in the direction of armature rotation
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304 THE GASOLINE AUTOMOBILE
increases the output of the generator, while moving it in the opposite
direction decreases the output. Whenever this brush is moved in either
direction, care should be taken to see that it makes perfect contact with
the commutator. Usually it should be seated to the commutator by
drawing a piece of fine sandpaper between the brush and the commutator,
with the sand side next to the brush. If this is not done, the brush will
seat imperfectly and the charging rate may increase when the brush
seats properly through wear. Whenever the charging rate is increased,
after the brush is properly seated, the maximum charging rate should be
noted. This should be done by slowly speeding up the engine and noting
the highest reading on the ammeter. In most cases it should not exceed
15 to 16 amperes.
245. Characteristics of Third Brush Regulation. — One of the out-
standing characteristics of generators with third brush regulation is that
the charging rate of the generator will increase gradually with increase in
speed, up to a car speed usually of 25 to 30 M.P.H., after which the charg-
ing rate will fall off as the speed continues to increase, so that at speeds
of 40 to 50 miles per hour the charging rate will be approximately \i of
its maximum value. This is an advantage in that the maximum charging
rate is obtained at normal driving speeds, while at high speed, such as
during cross-country touring, when the starter and lights are seldom used,
the decreased charging rate tends to prevent overcharging of the battery
and overheating of the generator.
Since third brush type generators depend upon the charging current
flowing through the armature winding to produce the field distortion
necessary for regulation, it is obvious that the generator is of the current
regulated type and must, therefore, have a complete charging circuit
available through the. battery at all times. In this respect, it is like the
other methods of regulators already discussed, with the exception of the
voltage type. Consequently, the same precautions are recommended in
keeping the battery terminals clean and tight.
To operate the car with the battery disconnected, care should be
taken to see that the generator does not build up a voltage. This may
be done, usually, either by grounding the main generator terminal or by
removing the shunt-field fuse.
246. The Remy Generator with Thermostatic Control — The Remy
generator, Fig. 367 and Fig. 368, is a 6-volt two-pole generator in which the
regulation is by the third brush principle, supplemented by a thermostat
mounted in the generator housing. The cut-out, Fig. 369, is mounted
either on the brush cap or on the generator frame, as may be seen in Figs.
367 and 368. The thermostat, Fig. 370, is composed of a resistance unit,
two silver contact points, and a spring blade at one end of which is
mounted one of the contact points. The blade is made of a strip of
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STARTING AND LIGHTING SYSTEMS
305
spring brass welded to a strip of nickel steel, a combination which warps
at its free end, when heated, due to the greater expansion of the brass
side. The spring tension is fixed so that it holds the two contacts firmly
REVERSE-
CURRENT
CUTcOUT
INDUCTION
,-COIL
REMOVABLE COVER
Fio. 367. — Remy generator, Model 234A.
REMOVABLE
COVET? s
V
REVERSE-CURRENT
J CUT-OUT
Pig. 368.— Remy generator, Model 257A.
Fig. 369. — Remy cut-out for generator, Model 234A.
together at low temperatures, but as soon as the temperature rises to
approximately 175° F., the blade bends and separates the contacts.
The thermostat is mounted above the commutator, on the same plate
20
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THE GASOLINE AUTOMOBILE
with the brush rigging, as shown in Fig. 371. It is connected in the
shunt-field circuit as shown in Fig. 372, so that when the thermostat
contacts are closed, full-field current passes through them and permits
full current output from the generator. After the engine has been run
for a sufficient time for the normally high charging rate to heat up the
generator and battery, the thermostat points open, due to the bending of
THERMO BLADE
RESISTANCE UNIT
CONTACT POINTS —
TO GENERATOR FIELD
FROM GENERATOR BRUSH
COLD AND CLOSED
TO GENERATOR FIELD
FROM GENERATOR BRUSH
HOT AND OPEN
Fio. 370. — Thermostatic control device for Remy generator.
the thermostat blade, thus causing the resistance to be inserted in the
shunt-field circuit, as shown in Fig. 370, and reducing the current output.
The generator current outputs, with the contacts closed and open, are
shown by the two curves in Fig. 373, from which it will be seen that the
charging rate reduces approximately J^ when the thermostat is opened.
THERMOSTAT ■
1
dBRUSH
Fig. 371. — Method of mounting Remy thermostat.
The chief advantages of the thermostatic control are that it gives a
larger battery charging rate in cold weather, when the efficiency of the
battery is lower than in warm weather, and also a larger charging rate
when the car is being driven intermittently and the demands on the
battery are greater, caused by the frequent use of the starting motor.
In summer it also prevents the generator and battery from overheating,
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STARTING AND LIGHTING SYSTEMS
307
by the reduction in the charging rate, when the temperature rises and
the thermostat opens.
LIGHTING
SYSTEM
rf
^NORMALLY OPEN
- VOLTAGE. COIL
-^ GROUND
CUT-OUT RELAY
(MOUNTED ON 5RU3H COVER)
CUT-OUT SPRING
COPPER STRIP
CURRENT COIL
BRASS CONTACTS
IRON CORE. AND
BASE -(INSULATED)
GROUND if-
LIGHTING SWITCH
AMMETER
LAMPS
m THERMOSTAT
(CONTACTS NORMALLY
CLOSED-OPEN AT 175 F.)
SHUNT FIELD
WINDING
STORAGE
BATTERf
t
i
GROUND CIRCUIT THROUGH FRAME
_GR
Fw. 372. — Circuit diagram of Remy generator and cut-out with thermostatic field control,
Model 234A.
247. The Remy Starting and Lighting System with Relay Regulation.
—The Remy starting and lighting system used on the Velie, Model 22 as
shown in Fig. 374 is a typical 2-unit system of the single-wire grounded
20-22-
14-15
CURVE "A" THERMOSTAT
CLOSED (COLO)
CURVE "IS" THERMOSTAT
OPEN (MOT)
CAR SPEED
Fw. 373. — Curves showing relative charging rates of Remy generator with thermostat
closed and open.
type. The generator is regulated by a vibrating type relay mounted on
one end of the generator frame.
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THE GASOLINE AUTOMOBILE
A circuit diagram of the generator, regulator, and cut-out relay is
shown in Fig. 375. As will be seen from the diagram, the regulator and
cut-out comprise two independent relays mounted side by side.
13
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The regulator consists of an electromagnet; an arm operating on
hardened bronze pivots; two sets of contact points held normally closed;
and a resistance unit. The contact points are of silver and the two on
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STARTING AND LIGHTING SYSTEMS
309
the arm are mounted upon springs. The cut-out is of similar construc-
tion, with the exception that a single set of contacts is used, the points
of which are held normally open. It will be seen that the regulator core
has a single winding — a current coil — while the cut-out has the usual vol-
tage and current windings.
When the engine, and, consequently, the generator, are running fast
enough to produce sufficient voltage for battery charging, the cut-out
closes through the action of the voltage coil and connects the generator
with the battery, the charging current flowing through the current coils
of both the cut-out and regulator in series. When the generator is
running at a speed lower than that required for maximum output,
GENERATOR
«EK
FIELD
fflftC.
Pio. 375. — Internal circuit diagram of Remy generator with relay regulator.
the regulator contact points are held together by a spring under the con-
tact arm and the current supplied to the generator field passes directly
through both of these points in series. As soon, however, as the speed of
the generator tends to cause its output to rise above the maximum value
predetermined, the charging current, which is flowing through the cur-
rent coil on the regulator core, magnetizes the core to such an extent that
it pulls the arm down. This pulls the contact points apart, forcing the
field current (which has heretofore been passing through these points)
to pass through the resistance unit. The added resistance in the field
circuit decreases the field current and in turn decreases the output of the
generator. This naturally reduces the energizing effect of the electromag-
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THE GASOLINE AUTOMOBILE
net, permitting the spring to force the contact points together again,
thereby cutting the resistance out of the field circuit. The generator
output immediately starts to build up again and the operation previously
described is repeated. A continuous repetition of this operation sends
a pulsating current to the generator field and holds the output of the
generator at practically a constant value. Thus it will be seen that the
regulator is of the constant current type as previously illustrated in Fig.
358.
For the purpose of protecting the generator, a readily accessible fuse
is fitted to the relay-regulator base. In case the battery should become
disconnected, either through accident or neglect, this fuse will burn out,
REGULATOR
FASTENING 5TUD
Disconnecting
plug
GENERATOR
CABLE CONDUIT
Fia. 376. — Bijur constant voltage generator and regulator.
opening the shunt field and rendering the generator inoperative and
damage proof.
248. The Bijur Generator with Constant Voltage Regulation.— The
Bijur constant voltage type generator, Fig. 376, is a practical application
of the constant voltage method of regulation as previously explained.
The circuit wiring diagram of the generator, regulator, and cut-out is
shown in Fig. 377. The cut-out, voltage regulating unit, and resistance
unit are fastened on a fiber board as a unit and mounted in an aluminum
box which fits on top of the generator. The box is provided with three
split connecting pins which fit into three receptacles in the generator so
that the mechanical act of putting the regulator box in place on the genera-
tor makes all of the necessary electrical connections between the generator
and the cut-out and regulating mechanism. In addition to the regulator
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STARTING AND LIGHTING SYSTEMS
311
box being held in place on the generator by its connecting pins, there is
a knurled screw passing through the box to the machine.
As may be seen in Fig. 376 and Fig. 377, connection from the generator
to the battery is made through a wire and plug which fits into the recep-
tacle at one end of the relay box. In this receptacle there are two spring
plungers which make contact with two contacts mounted in the dis-
connecting plug. The plug is designed so that it can be rotated through
a small angle after it is in place, for the purpose of reversing the connec-
tions of the contacts. By reversing the plug, the generator polarity
is also caused to reverse, which in turn reverses the polarity of the regula-
tion vibrating points. The purpose of this is to equalize any transfer
of metal on the regulator p'oints, thereby decreasing their tendency to
fttSISTAKCE .UNIT
VOLTAGE |
REGULATOR
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CU*ITENT COIL
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RECEPTACLE FOR
DISCONNECTING PLUG
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(REGULATOR BOX MOUNTED ON TOP OF GENERATOR ) ^SJNX BATT
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GENERATOR
Fio. 377. — Wiring diagram of Bijur voltage regulator and generator.
pit and, consequently, greatly increasing the life and efficiency of the
regulator. It is recommended that this disconnecting plug be reversed
to reverse the generator polarity about every 500 miles of travel. By
merely reversing the plug, the polarity of the generator will reverse
automatically when the engine is started.
249. The Westinghouse Starting and Lighting System — Voltage
Regulator Type. — The Westinghouse generator No. 400, Fig. 378,
together with the regulator, Fig. 379, is typical of the Westinghouse
equipment of the relay regulated type installed on 1916 and 1917 cars.
The construction of this generator was shown in Fig. 342. A complete
wiring diagram showing a typical installation of this type system is
shown in Fig* 380 in which is shown the starting, lighting, and ignition
wiring for the Glide "six-40."
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312 THE GASOLINE AUTOMOBILE
As may be seen from the circuit diagram of the generator and relay
shown in Fig. 381, the relay performs two functions: (1) that of a cut-out
which automatically connects and disconnects the generator from the
battery when the generator is driven, respectively, above or below a
predetermined speed; and (2) that of an "automatic voltage regulator"
which, after the cut-out has connected the generator circuit to the
battery, automatically keeps the generator voltage at a predetermined
value. Bach function of the relay is performed by its individual element;
however, the successful operation of the regulating function depends upon
the proper operation of the cut-out. The core of the relay is of the " three-
legged " or W type, which has two magnetic circuits, one for operating
the cut-out contact arm, the other for operating the regulator points.
REGULATOR
ADJUSTING SCffEW
CUT-OUT CONTACTS
COYER REMOVED COMPLETE
1
Fio. 378. Fio. 379.
Fio. 378. — Westinghouse generator, Type 400, with vertical ignition unit.
Fio. 379. — Westinghouse voltage regulator for separate mounting.
CutrovJL. — When the generator is being operated at a speed below the
predetermined "cut-in" speed, the contacts of the cut-out are open,
the voltage of the generator being below that of the battery. When the
generator speed reaches the "cut-in" speed these contacts are closed,
connecting the generator to the battery circuit. The "cut-in" speed
varies from 5 to 10 miles per hour on igh gear, depending upon the
gear ratio and wheel diameter of the particular car.
The "cut-in" speed of the generator can be observed by running the
car, allowing it to increase in speed slowly, and observing on the speed-
ometer the speed at which the car is running when the cut-out contacts
close, which is indicated by a slight movement of the ammeter needle
toward the "charge" side.
The relay is constructed so that the cut-out operates to disconnect
the generator from the battery circuit at a speed slightly below the
"cut-in" speed. This enables the cut-out portion of the relay to keep
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314
THE GASOLINE AUTOMOBILE
the circuit closed, instead of continuously opening and closing it when the
car is being run at speeds close to the " cut-in" speed. This discon-
necting of the generator from the battery circuit, when the generator
voltage is below the battery voltage, insures that the battery will not
be discharged through the generator.
Regulator. — As will be seen from the diagram, the regulator is of the
combined current and voltage regulating type. The shunt field of the
generator is connected by a wire to the middle terminal F on the relay,
REGULATING
CONTACTS
VOLTAGE COIL
(FINE WJNDIN6}
REGULATOR CASE
MUST BE GROUNDED.
REGULATING
RESISTANCE UNIT or/
SRRIMGS
REGULATOR ADJUSTING SCREW
SHUNT
FIELD
%?mLD-l REGULATOR AND
• CUT-OUT RELAY AMMETER
(MOUNTED ON ffEAff OF DASH)
STORAGE
BATTERY
tot
^4
to*
^E__ CIRCUIT THROUGH CAR FRAME
GROUND
GR.
GENERATOR
Fio. 381. — Circuit diagram of Westinghouse, Type 400 generator, with voltage regulator.
the field circuit being completed through this wire, the regulator contact
points, and the wire which connects to terminal A — .
When the generator is operating below "cut-in" speed, the regulator
contacts are closed, and remain closed, short-circuiting the resistance
unit until the generator armature is revolved at a speed sufficient to
produce the maximum charging rate set for the battery. When, due
to the increased speed and current output of the generator, the voltage
and current tend to exceed the value for which the regulator is set, the
strength of the magnetic circuit through the regulating side of the relay
will be increased by the action of the voltage and current coils sufficient
to attract the regulator contact arm, pulling the contacts open. This
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STARTING AND LIGHTING SYSTEMS
315
cuts the regulating resistance into the shunt-field circuit and reduces the
field strength which in turn causes a momentary drop in voltage so that
the contacts close again. This opening and closing of the contacts is
continuous and so rapid as to be imperceptible to the eye, and to hold the
voltage and current fairly constant.
The maximum current output of the generator can be increased or
decreased by increasing or decreasing the spring tension on the regulator
points. This may be done by turning the regulator adjusting screw
on the top of the relay shown in Figs. 379 and 381. Care should be taken
in making this adjustment to make sure that the generator does not
become overloaded. The usual maximum charging rate for this genera-
tor should be fixed to not exceed 10 to 12 amoeres.
Pio. 382. — Typical Westinghouse third-brush type generator. (A) generator Model No.
250; (B) generator Model No. 760 with vertical ignition unit for cradle mounting; and (C)
generator Model 760 for flange mounting.
260. The Westinghouse Starting and Lighting System — Third Brush
Type. Generators. — Several models of Westinghouse Third Brush type
generators are shown in Fig. 382. These generators are four-pole shunt
wound with Third Brush regulation. In A, which shows the generator,
model No. 450, the construction is very similar to that of the No. 400
generator, Fig. 378, the construction of which was shown in Fig. 342.
B and C illustrate the types known as No. 760.
The type No. 760 generator is the one more widely used. It is fur-
nished either with or without the ignition unit carrying bracket and for
either flange or cradle mounting. The cut-out is mounted either separate
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316
THE GASOLINE AUTOMOBILE
from the generator or inside the generator frame. When located inside
the generator, it is mounted on the end bracket which supports the brush
Fig. 383.-
-Brackets for Westinghouse Third-brush generator, with self-contained cut-out
(right) and with separately-mounted cut-out (left).
rigging, as shown in Pig. 383. The operation of the generator is the
same as that previously explained for generators having Third Brush
regulation.
Fig. 384. — Westinghouse starting motor with automatic electromagnetic pinion shift.
Starting Motors. — Westinghouse starting motors are made in two
general types: (1) with mechanical pinion shift as shown in Figs. 331
SMin* HUSHING
Fia. 385. — Parts of Westinghouse starting motor with electromagnetic pinion shift.
and 351; and (2) with automatic electromagnetic pinion shift, as shown
in Figs. 384 and 385. The first type is the more commonly used. Its
operation is the same as previously explained for starting motors equipped
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STARTING AND LIGHTING SYSTEMS
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with the Bendix drive. Construction of the Westinghouse starting
switch is shown in Fig. 386.
The starting motor of the electromagnetic pinion shift type is com-
posed of three principal parts as shown in Fig. 385: the stationary parts,
or field; the rotating parts, or armature and shaft; and the shifting mag-
f biffing Magnet Storting Motor
%—mK= p,nwn
Fio. 386. — Westinghouse starting switch, foot operated type.
net. The armature is mounted on a hollow shaft, on the end of which is
mounted a splined pinion which drives the flywheel. This pinion is made
to slide along the shaft by a shifting rod which is attached to the pinion
and passes through the hollow shaft. The other end of this shifting rod
acts as the core of the shifting magnet. When the motor armature is
not revolving, a return spring holds the pinion
at the end of the shaft and clear of the fly-
wheel gear. A diagram of this type of
starter is shown in Fig. 387. As shown in
the diagram, when the starting switch is
closed a circuit is complete from the posi-
tive (+) terminal of the battery, through
the "ground" or frame of the car, through
the series field, armature, and shifting mag-
net, through the starting switch to the nega-
tive (— ) terminal of the battery. The start-
ing motors used in this application are of
the series type; that is, the field is connected
in series with the armature so that all the
current flowing through the one also flows
through the other. One of the characteristics of this kind of motor is
that the amount of current flowing through it is proportional to the
amount of energy it develops.
When the starting switch is closed, current flows through the circuit
as outlined, causing the armature, the shaft, and the pinion to rotate.
The motor requires a high current at the instant it starts from rest.
Fig. 387. — Diagram of
Westinghouse starting motor for
automatic electromagnetic
pinion shift shown in Fig. 384.
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318
THE GASOLINE AUTOMOBILE
This high current through the shifting magnet magnetizes it sufficiently
to overcome the force of the return spring, and, therefore, draws the shift-
ing rod through the shaft, thus sliding the pinion into mesh with the gears
on the flywheel. The teeth on the flywheel and the pinion are cut diag-
Fia. 388. — North Eaet starter generator.
Model G.
Fig. 389. — North East combined start-
ing switch and reverse-current cut-out.
Type 8100.
onally so that they mesh very easily. As soon as the pinion meshes
with the flywheel gear, the current required to turn the engine over is
enough to hold the pinion in mesh until the engine fires. When the engine
picks up, it soon runs at higher
speed than that of the motor.
When the engine speeds up so
that its speed approaches the no-
load speed of the motor, the cur-
rent in the latter falls off so that
the pull of the shifting magnet is
less than that of the return
spring, which, therefore, throws
the pinion to its original position
clear of the flywheel. The motor
will continue to revolve, without
load, however, until the starting
switch is opened or released; but
the pinion remains out of mesh,
because the current required to
turn the motor armature over is
not enough to energize the shifting magnet sufficiently to pull the
pinion back into mesh against the force of the return spring.
251. The North East Starting and Lighting System on the Dodge Car.
— The North East Starting and Lighting system on the Dodge Broth-
ers Motor Car comprises the North East, Model G, starter-generator,
Fig. 390. — Battery indicator.
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STARTING AND LIGHTING SYSTEMS
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dWin QV3M J.H9I*
*W*-I 0V3M uri
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THE GASOLINE AUTOMOBILE
Fig. 388, and the combined starting switch and reverse current cut-out,
as shown in Fig. 389, together with the following accessory parts not
of North East manufacture: the storage battery; the charging indicator,
Fig. 390; the lighting (and ignition) switch; the head-lamps, dash-lamp,
and tail-lamp; and the necessary cables for completing the electrical
connections between these several elements of the system.
6CKIC* HELD
WINDING
REVERSE.- CURRENT
CUT-OUT ^4
UGMTINO
I«mition
%W1TCH
Fio. 392.-
DATTERY
(12 VOLT)
-Circuit diagram of North East starter-generator, Model G and reverse current
cut-out.
The starter-generator serves to start the engine and to provide current
for the lamps and other electrical accessories as well as for the ignition
system. The battery acts as the source of current while the engine u
not in operation or is running slowly, but at all engine speeds above 350
r.p.m. the starter-generator converts automatically into a generator and
supplies current to the entire electrical system.
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STARTING AND LIGHTING SYSTEMS
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In Fig. 391 is shown a complete wiring diagram of the car, and in
Fig. 392 the circuit wiring of the starter-generator and reverse current
cut-out. In these diagrams the starting circuit is represented by the
very heavy cables; the charging circuit, where it does not coincide with
the starting circuit, by the cables of medium weight; and the lighting
and the ignition circuits by the lightweight cables.
As will be seen from the diagram, the starting circuit extends from the
positive terminal of the battery through the starting switch, through the
starter-generator armature and field coils, back to the negative terminal
of the battery by way of the grounded negative starter-generator termi-
nal, the car frame, and the battery ground connection. The charging
circuit is identical with the starting circuit, except at the starting switch,
Fig. 393. — Readings of battery indicator.
where instead of passing from one switch terminal to the other through
the switch contacts, it extends through a parallel path which includes
the reverse current cut-out and the charging indicator. The cable
leading to the lighting and ignition switch is attached to the positive
terminal of the indicator. From this switch the lighting and the ignition
circuits become distinct; and each, after passing through its proper course,
reaches the car frame and returns through it to the source of supply.
Owing to the fact that the charging circuit does not coincide entirely
with the starting circuit, either an ammeter or a battery indicator of
the C. O. D. type may be used. This indicator reads " Charge," "OB,"
or "Discharge" as shown in Fig. 393, depending upon whether the
battery is being charged or discharged.
The starter-generator is mounted on the left-hand side of the engine
2J
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322 THE GASOLINE AUTOMOBILE
by means of an adjustable support and a clamping-strap and runs at
three times engine speed, being driven directly from the crankshaft
through a silent chain drive. The dynamo, being a single-unit machine,
employs but one armature with only one commutator; one set of field
windings; and one set of brushes for the performance of all of its functions,
both as a starter and as a generator. The dynamo operates at 12 volts,
when operating both as a motor and as a generator.
As may be seen from Fig. 392, the dynamo, while starting the engine,
acts as a cumulative compound-wound motor; but while serving as a gen-
erator operates as a differentially compound-wound machine. Generator
regulation is effected by the Third Brush principle in combination with
the differential influence of the series field upon the shunt field.
When the dynamo is driven as a generator, the armature normally
begins to deliver current to the battery when the car speed is approxi-
mately 10 miles per hour. From this point on, the charging rate rises
rapidly with increasing speed until the standard maximum rate of 6 am-
peres is reached at a car speed of 16 to 17 miles per hour. From this
speed to 20 or 21 miles per hour the rate remains practically constant;
but above 21 miles per hour it decreases gradually until at the upper
speed limit of the engine it may become as low as 3 amperes. Since
generator regulation is taken care of by the Third Brush principle in
combination with the differential effect of the series field upon the shunt
field, the charging current may be adjusted by shifting the third brush.
This can be done with a screwdriver, by turning the special adjusting
screw in the brush end cap.
Without exception, all of the connections of the starting and lighting
system must be made exactly as indicated in the diagrams, if satisfac-
tory results are to be obtained from this equipment. Special care should
be taken to see that the ground wire on the cut-out makes good connec-
tion at all times, as an open at this point would prevent the cut-out from
closing. The shunt field is provided with a fuse which should be removed
in case the car is to be operated with the battery disconnected.
262. The Delco Single-unit Starting, Lighting, and Ignition System
on the Buick. — The principal parts of the Delco starting, lighting, and
ignition system used on the Buick "six" consists of the motor-generator
Fig. 394, the combination lighting and ignition switch, Fig. 395, and a
6-volt storage battery.
The motor-generator is mounted on the right side of the engine and
is arranged so that the extension of the water pump shaft drives the
armature through an overrunning clutch whenever the engine is in
operation. At the rear of the motor-generator are the starting gears,
as shown in Fig. 396. These are assembled in the bell housing covering
the flywheel, and are for the purpose of making connection between the
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STARTING AND LIGHTING SYSTEMS
323
armature shaft and the flywheel for the cranking operation. An over-
running clutch, Fig. 396, is built in the largest of these gears, to prevent
driving of the armature from the flywheel end.
The armature in the Delco motor-generator differs from the usual
form of construction in that it is double wound, having two separate
windings and commutators, one being for th$ motor, the other for the
generator. The brushes are so arranged on the two commutators, as
shown in Fig. 397, that when the starting pedal is pushed down and the
motor-generator is being used to crank the engine, both of the motor
brushes make contact with the motor commutator, while at the same time
one of the generator brushes is lifted off. However, when the starting
TERttlNAL CONNECTED
TO SWITCH
SHUNT FIELD.
WIRE
IGNITION COIL
Ml TERMINAL
THIRD BRUSH
SUPPORTING PLATE
Fio. 394. — Delco motor-generator for Buick "six.'
pedal is released, one of the starting brushes is automatically raised and
the lifted generator brush dropped to make contact with its commutator,
thus permitting the dynamo to operate as a generator. The generator
output is regulated by the Third Brush principle.
The system has no cut-out as is usually found in most systems, the
closing and opening of the charging circuit being taken care of by the
turning on and off of the ignition button. A circuit diagram of the sys-
tem is shown in Fig. 398. As will be seen, the combination switch
controls the lighting and ignition circuits, and the circuit between the
generator and the storage battery. The button on the extreme left
of the switch controls the main head lights; the second button controls
the auxiliary head lights; the third button controls the rear and cowl
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THE GASOLINE AUTOMOBILE
lights; while the fourth button, marked "IGN," controls both the
ignition circuit and the circuit between the generator and storage battery.
By controlling the latter circuit, the combination switch thus performs
the function of an automatic cut-out as is commonly used for this pur-
pose. For this reason, the " IGN " button should not be left in the "on"
position when the engine .is not running.
On the back of the combination switch
is located the circuit breaker which takes
the place of fuses. This is a protective de-
vice which prevents excessive discharging of
the storage battery, or damage to the switch
or light wires in the event of a ground on
any of these wires. All of the current for
the lights is conducted through the circuit
breaker. Whenever an excessive current flows through the circuit
breaker, it opens the circuit intermittently, causing a clicking sound.
This will continue until the ground is removed, or the switch is operated
to open the circuit on the grounded wire. When the ground is removed,
the circuit is restored automatically, there being nothing to replace as is
the case with fuses.
Fig. 395. — Delco combination
ignition and Ughting switch.
ing Gear
Shifting Rod
LKtr-hunning
Clutch
Fig. 396. — Starting gears and overrunning clutch on Deloo motor-generator.
The numbers on the switch terminals correspond with the numbers
on the circuit diagram, thus making it comparatively easy to connect up
this switch if for any reason it has been disconnected. Referring to
Figs. 394, 397, and 398, the motor generator performs three operations
as follows:
(A) Motoring the Generator. — This operation is necessary in order
that the starting gears may be brought in mesh with the small gear
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STARTING AND LIGHTING SYSTEMS
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on the armature shaft and with the teeth on the flywheel. This takes
place whenever the ignition button on the combination switch is pulled
out. This button completes the circuit from the storage battery to the
generator windings and allows current to be discharged from the storage
battery through the shunt-field winding and the generator windings on
the armature, thus causing the armature to revolve slowly.
(B) Cranking Operation. — The cranking operation is performed when
the starting gears are brought fully in mesh and the motor brush makes
contact with the commutator. This is arranged so that the starting
gears are fully in mesh before the motor brush makes contact on the com-
mutator. Since considerable power is required for the cranking opera-
tion, a heavy discharge from the storage battery is necessary. The
ftHUNT FIELD LEAP
ADJUSTMENT
Fio. 397. — End view of Delco motor-generator showing brush arrangement.
cranking circuit is made up of heavy copper cable and the motor brushes
and motor windings are designed to operate with a large current. For
this reason, there must be no loose or poor connections in this circuit.
All battery connections, motor connections, and motor brushes must
make good electrical contact.
(C) Generating Electrical Energy. — After the cranking operation
is completed, the starting pedal is returned by a spring. This disconnects
the starting gears, raises the motor brush, and allows the generator brush
to make contact with the commutator while the armature is driven by the
extension of the pump shaft. At very low engine speeds, the voltage
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THE GASOLINE AUTOMOBILE
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generated is not sufficient to overcome the voltage of the storage battery
and a small amount of current may be discharged from the battery
through the generator winding; but this amount is very small. At all
normal engine speeds the voltage of the generator exceeds that of the
storage battery, and current is either charged into the storage battery
or is used directly for lights, horn, and ignition.
The ammeter on the combination switch is for the purpose of indicat-
ing the amount of current that is being charged into the storage battery
or discharged from it, with the exception of the cranking current.
The generator commences to charge the battery at engine speeds
corresponding to 7 miles per hour on high gear, providing no current
is being used for lights. The output of the generator increases up to
approximately 25 miles per hour, and at the higher speeds the output
is decreased. This characteristic is due to the Third Brush principle
Fio. 390. — Deloo generator and ignition unit for Oldsmobile Eight.
of regulation employed. The maximum charging rate usually should be
about 16 amperes.
263. The Delco Two-unit Starting, Lighting, and Ignition System on
the Oldsmobile Eight. — The starting and lighting system as equipped
on the Oldsmobile Eight, model 45A, is a typical Delco system of the
two-unit type. It consists of a generator and ignition unit, Fig. 399;
a starting motor, Fig. 400; a combination ignition and lighting switch,
Fig. 395 (same as used on the Buick "six") ; a starting switch, Fig. 401;
and a 6-volt storage battery. The external wiring of the car is shown
in Kg. 402.
The generator with the ignition unit is mounted between the cylinders
in front of the carburetor and is driven by the fan belt as shown in Fig.
403. The starting motor is located back of the flywheel on the lower
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THE GASOLINE AUTOMOBILE
right side, the drive between the starting motor and the flywheel being
by means of the Bendix drive.
Like the single-unit system, no reverse current cut-out is used, the
closing and opening of the charging circuit being controlled by the igni-
tion button as may be seen from the circuit diagram in Fig. 404. It
BENDIX DRIVE
TO FLYWHEEL
Fio. 400. — Deloo starting motor for Old smo bile Eight.
will also be seen that the lighting circuits are protected by a circuit
breaker the same as on the Buick, instead of fuses. The generator is
of the two-pole shunt-wound type regulated by the Third Brush method
of field control. By this manner of regulation it is possible to obtain the
highest charging rate between 15 to 25 miles per hour. The maximum
Jr/r/M3
foorOvTroN
Fio. 401. — Delco starting switch.
charging rate should be about 15 amperes at 20 miles per hour on high
gear. If the ammeter indicates an appreciably higher charge than
this, the charging rate should be adjusted by shifting the third brush
slightly in the opposite direction to armature rotation. In case such
an adjustment is made, care should be taken to make sure that the
third brush makes perfect fit with the commutator. The arrangement
of the brushes is shown in Fig. 405.
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THE GASOLINE AUTOMOBILE
It will be noted in the circuit diagram of the starting motor, Kg.
404, that each of the four field coils is connected in parallel with another
field coil, each pair being in series with the armature winding. The
winding of the motor is such that the armature is in the circuit between
the two pairs of field windings. The starting circuit is shown by the
heavy black lines in the diagrams. Care should be taken to see that
the battery terminals are kept free from corrosion at all times to insure
proper operation of the starter.
264. Delco-Liberty Lighting System on U. S. Standardized Military
Truck, Class B. — The special Delco generator used on the U. S. Stand-
ardized Military Truck, Liberty — Class B, is shown in Fig. 406. The
generator is mounted in a housing on the right side of the crank case,
Fig. 403. — Delco generator installation on Oldsmobile eight-cylinder engine, Mode) 45A.
and#is held in place by a large set screw through the top of the housing,
the armature being driven from the rear end of the governor shaft
through an Oldham coupling. A complete wiring diagram of the truck
is shown in Fig. 407.
As may be seen from the diagram, the current output of the generator
is regulated by the Third Brush method. The generator starts charging
at low speed, and the output increases with speed until a maximum
output is reached, when it starts to decrease. The maximum output,
as indicated by the ammeter on the dash, should be 10 to 13 amperes,
with all the lights turned off. If it is considerably higher than this,
or if it is so low that the battery does not get sufficient charge, the output
may be adjusted. This may be done by loosening the three screws
in the small circular plate on the commutator end of the generator, as
shown in Fig. 406, and shifting the third brush. To raise the output,
this plate, which connects with the third brush, should be rotated slightly
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332
THE GASOLINE AUTOMOBILE
in a clockwise direction (same as armature rotation), and to lower the out-
put the plate should be rotated slightly in a counterclockwise direction.
This system contains no reverse current cut-out, this function being
provided for by the ignition switch. The generator is driven by an Old-
GENERATOR COMMUTAT
GENERATOR
TERMINAU
ELD COIL
THIRD BRUSH
ADJUSTMENT
GENERATOR
6RUSH
THIRD
BRUSH
Fio. 405. — Arrangement of brushes on Delco generator used on Oldsmobile Eight.
ham or double cross-type coupling which contains a ratchet clutch.
When the ignition switch is turned on while the engine is still, the gen-
erator, being connected to the battery, starts to run as a shunt-wound
motor and draws a small amount of current from the battery. As the
generator revolves, the clutch ratchet operates and a clicking noise is
REMOVABLE BAND GIVING ACCESS
TO COMMUTATOR AND BRUSHES
OIL CUP
PLATE WITH LOCKING
SCREWS TO ADJUST SETTING
OF THIRD BRUSH
Fio. 406. — Delco generator for Liberty-Class B, military truck.
heard. This is an indication that the generator is functioning properly.
It is also a warning that the ignition switch is " On," and unless the driver
is about to crank the engine, the switch should be turned "Off."
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334 THE GASOLINE AUTOMOBILE
The ignition and lighting switch contain, besides the two switches,
an ammeter, a circuit breaker, and an instrument lamp, as shown in Fig.
407.
Ignition TSmtch. — The ignition switch has one "Off" and one "On"
position and controls both of the ignition systems. In the "Off" posi-
tion the magneto is grounded and the generator and battery ignition are
disconnected from the battery. In the "On" position the battery is
connected to the generator, and the battery and magneto ignition systems
both operate simultaneously.
The ignition switch should always be turned off unless the truck
is to be operated. If the switch is allowed to remain "On" with the
engine not running, the battery will become discharged after several
hours, and starting will be very difficult.
Lighting Suritch. — The lighting switch has three positions:
First position: Lights the danger zone or side lamps.
Second position: Lights the side, instrument and tail lamps.
Third position: Lights the head, instrument and tail lamps. This
order was reversed on some of the first trucks.
Instrument Lamp. — The instrument lamp is provided with inner and
outer covers which are removable for replacement of the bulb. The outer
cover is arranged so that it may be rotated until the light is entirely
shut off.
Ammeter. — The ammeter always indicates the actual current going
into the battery or being taken out of it.
Circuit Breaker. — The circuit breaker which is mounted on the back
of the switch is connected in the lighting circuit. When a ground occurs
on the lighting circuit, the circuit breaker operates with a buzzing or
rattling noise until the cause of the trouble is removed. The circuit
breaker also greatly reduces the discharge current caused by the ground
or short-circuit and prevents the wires from burning and the battery
from becoming quickly discharged.
255. The "F. A." Liberty Ford Starting and Lighting System.— The
"F. A." Liberty starting and lighting system installed on Ford sedans
and coupelets consists of a starting motor, a generator, a charging
indicator or ammeter, a combination ignition and lighting switch and
the lights, together with the necessary wiring and connections. The top
view of the Ford engine showing the generator and motor installation
is shown in Fig. 408.
Starting Motor. — The starting motor, Fig. 409, is a typical 4-pole
series wound 6-volt motor, mounted on the left-hand side of the engine
and bolted to the transmission cover. When in operation, the pinion
of the Bendix drive shaft meshes with the teeth on the flywheel, thus
turning the crankshaft over.
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STARTING AND LIGHTING SYSTEMS
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Generator. — The generator, Fig. 410, is a 6-volt, 4-pole, Third Brush
type of generator mounted on the right-hand side of the engine and bolted
STARTING MOTOR
MAGNETO
TERMINAL
^IGNITION
TIMER
GENERATOR
Pio. 408. — Top view of Ford engine showing installation of Liberty generator and starting
motor.
STARTING MOTOR
/TERMINAL
BEND1X DRIVE
TO FLYWHEEL
Fig. 409. — "F. A." Liberty starting motor for Ford car.
GENERATOR
/TERMINAL
OIL HOLE
DRIVING PINION
Fio. 410.— "F. A." Liberty generator for Ford car.
to the cylinder front end cover. It is driven by the pinion of the armature
shaft meshing 'with the large timing gear. The charging rate of the
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THE GASOLINE AUTOMOBILE
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generator is set so as to "cut-in" at engine speeds corresponding to 10
M.P.H. and reaches a maximum charging rate at 20 M.P.H. At
higher speeds, the charging rate will taper off — a characteristic of Third
Brush regulation. The closing and opening of the charging circuit at
suitable speeds is accomplished by the reverse current cut-out relay,
which is mounted on the back of the dash.
Lighting System. — The lighting system consists of two headlights and
a tail-light all operated by a combination lighting and ignition switch
located on the instrument board. The lighting system is of the ground
return type, the car frame serving as a return path for the current from
the lamps to the negative terminal of the battery. All of the lamp bulbs
are connected in parallel so that the burning out or removal of any one
of them will not affect the other. The wiring diagram, Fig. 411, shows
the different circuits and the course of the current.
Ammeter. — The charging indicator or ammeter, Fig. 412, is located on
the instrument board. This indicator registers " charge" when the gen-
erator is charging the battery, and
"discharge" when the lights are burn-
ing and the motor not running above 10
M.P.H. At an engine speed of 15
M.P.H. or more the indicator should
show a reading of from 10 to 12 am-
peres with the lights off and from 4 to
6 amperes with the lights on bright.
Lubrication. — The starting motor is
lubricated by the Ford splash system,
the same as the engine and trans-
mission. The generator is lubricated
by a splash of oil from the timing gears.
In addition, an oil cup is located at the
end of the generator housing. A few
drops of oil should be applied every two weeks or about once each 500
to 1000 miles of travel.
Operating the Car with Battery Removed. — If for any reason the engine
is to be run with the generator disconnected from the battery, as on a
block test, make sure that a copper wire is connected between the terminal
on top of the generator and one of the valve cover stud nuts. This
"shorts" the main brushes and prevents the generator from building up
a voltage. Failure to do this when running the engine with the generator
disconnected from the battery will no doubt result in serious injury to
the generator field and armature windings.
Caution. — Care should be taken to prevent an accidental short circuit
between the battery terminal No. 3 and the magneto terminal No. 2 on
22
Fio. 412. — Dash type ammeter as
used on Ford car.
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THE GASOLINE AUTOMOBILE
the terminal block located on the back of the dash. Since the introduction
of a battery current into the magneto winding may discharge the magnets,
the positive wire should be disconnected from the battery whenever
repairing is necessary in the ignition system or car wiring. The end of
this wire should be wound with tape to prevent its coming into contact
with the ignition system or metal parts of the car.
266. Automobile Lamps and Reflectors. — Headlight Focusing. — In all
automobile electric headlights having a parabolic shaped reflector,
there is a theoretical point of focus from which any light rays will be
reflected in parallel rays directly ahead of the lamp reflector. Con-
sequently, to secure the best lighting results the bulb filament should
, be located at this focal point. To
accomplish this, all head lamps are
equipped with some method of focus
adjustment, one common type being
that shown in Fig. 413.
In focusing a lamp it is necessary
to move the lamp bulb forward or
backward to a point where the re-
flected rays give the desired lighting
effect. To do this, it is usually neces-
sary to open the front of the lamp
and either remove the reflector and
adjust the bulb from the back of the
reflector, or, in the type shown,
merely turn the adjusting screw at
the top of the reflector. By turning
the screw to the right the bulb will
be moved toward the reflector, while
by turning the screw to the left the
bulb will be moved away from the
reflector.
One lamp at a time should be focused, the other being covered in
order that the rays of one shall not interfere with the rays of the other.
The best place to focus the lamps is on a dark road. A good plan is to
first focus the reflected light into a small ray or pencil beam, then align
this beam properly with the road by resetting the lamp supports, making
sure that the car is pointed so that the light will project straight ahead,
as desired under ordinary driving conditions. In most states, the dim-
ming laws require that with the car on the level, the reflected beam of
light from either lamp should not rise more than 42 in. from the ground
at a point 75 ft. in front of the car.
Lamp focus adjustment may also be accomplished by placing the car
Fio. 413. — Sectional view of head lamp
showing lamp focusing adjustment.
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STARTING AND LIGHTING SYSTEMS
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3
10
15
18
21
0.5
1.62
2.5
3
3.5
3
9.72
15
18
21
in a level position where the light can be projected on a wall 50 to 100 ft.
from the car. With the car in this position, the lamp bulb should be
moved forward or backward until the light on the wall indicates the
greatest brilliancy, and free from dark spots or rings.
In replacing lamp bulbs, care should be taken to replace them with
bulbs of the proper voltage and of no higher current consumption than
intended for the system. This is to prevent an excessive load on the
battery and generator. The current consumption of Mazda lamps for
automobiles is as follows:
Candle-power 1J£
Current in amperes 0. 25
Watts 1.5
From the table it will be noted that the power consumption of headlight
bulbs is one watt per candle-power.
Dimming. — The devices commonly employed to meet non-glare re-
quirements usually make use of one of the following principles: (1)
reducing the amount of light at its
source either by means of a resistance
unit or by connecting the headlights
in series; (2) diffusion or spreading
of the pencil rays through special
lenses; (3) deflection of the pencil
rays below the level at which the
glare is objectionable by means of
special lenses or reflectors; (4) auxil-
iary small bulbs placed in the head-
light out of focus; and (5) tilting the
headlight reflector.
In Fig. 414 is shown a cross sec-
tion view of the reflector tilting type
of headlight used on the Cadillac
Eight. The reflectors in the head-
lamps are pivoted so that they may
be tilted, being controlled by a lever
on the steering column. When the
road is clear and the illumination of
the distant road is desired, the re-
flectors are adjusted to direct the light straight ahead. When a vehicle,
traveling in the opposite direction approaches, the reflectors are tilted
down by simply raising a small lever on the steering column, thus deflect-
ing the rays below the level of vision of the occupants of the approach-
ing car, and increasing the illumination directly in front of the car,
where it is most needed.
Fio. 414. — Section of head-lamp used
on Cadillac Eight showing method of tilt-
ing reflector for dimming.
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340 THE GASOLINE AUTOMOBILE
Cleaning Reflectors.— When lamp reflectors become tarnished, great
care should be taken in cleaning them to prevent scratching of the reflect-
ing surface. The reflector, being plated with pure silver and being very
highly polished, is very easily scratched unless great care is exercised,
even if cleaned with soft material. If reflectors have become dull from
long service, they can be polished by using a clean chamois and rouge or
crocus such as is used by jewelers for cleaning watches. The chamois
should be soft and free from dust, and should not be used for any other
purpose. To polish the reflector, the chamois and rouge, dampened with
alcohol, should be used first to remove any spots or heavy tarnish. The
reflector should then be wiped off using a second piece of chamois with
dry rouge. This will give a very high finish. The polishing should be
done in a rotary motion, as indicated
by the arrows in Fig. 415, to avoid
leaving marks on the reflector. The
fingers should not come in contact
with the reflecting surface.
257. Care of Starting and Light-
ing Apparatus. — In order to procure
the best results from any mechanical
or electrical device, it is important
that it be properly installed, prop-
erly operated, and reasonably well
cared for. The automobile owner and
mechanic can eliminate many of the
Fio. 415.— Method oTdeaning head- common starting and lighting troubles
lamp reflectors. by an occasional inspection of the
different equipment, and seeing to
it that all parts are working properly.
Lubrication. — In practically all starting motors and generators, the
bearings, which are usually of the anti-friction type — either ball bearings
or roller bearings — are provided with an oiler for lubrication of the bear-
ings. The lubrication required by the different systems varies with the
type of bearing used; however, a general practice which may be followed
is to oil each bearing of the generator with 5 or 6 drops of light high-grade
oil every 2 weeks or every 500 to 1000 miles of travel, and the starting
motor, about once each two months of service. Care should be taken not
to over-oil or to get oil on the commutator and brushes.
Commutator and Brushes. — A removable band which provides access
to the commutator and brushes is usually placed around the commutator
end of the generator. Inspection of these parts every 2500 to 3000
miles should be sufficient. The commutator wears naturally to a brown-
ish surface in normal use, but if it appears black or scored, the surface
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STARTING AND LIGHTING SYSTEMS 341
should be smoothed with a piece of fine No. 00 sandpaper. Never use
emery doth for this purpose. Care should be taken to blow out all the
dust, also to see that the brushes move freely in their pivots or holders
so that the spring tension holds them in good contact with the commu-
tator. When replacing the cover, care should be taken to have the ends
of the band come over a solid part of the generator frame to close the gap
and exclude all dirt, water, and oil from the commutator and brushes.
When new brushes are to be installed, they should be made to fit perfectly
on the commutator. It is always a good policy to use only the brushes
sent out by the manufacturer of the machine.
Wiring. — All wiring should be inspected several times each season
to see that all terminals are tight and that all wires are perfectly insulated
and not in rubbing contact with the car frame or any moving parts, as the
continuous vibration and rubbing will wear the insulation away, causing
harmful "grounds" and short circuits. One of the most important pre-
cautions to take is to keep the battery terminals free from corrosion, and
tight.
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CHAPTER XI
THE AUTOMOBILE CHASSIS AND RUNNING GEAR
The automobile chassis includes all parts of the car with the exception
of the body and its immediate accessories. These parts are the frame,
springs, axles, steering gear, wheels, brakes, transmission system, and the
power plant with its accessories. Figure 416 is a plan view of the Stude-
baker Six chassis with all of the principal parts indicated, and Fig. 417
is a section view of the Packard Twin Six chassis.
268. General Arrangement of Chassis. — The power plant of an auto-
mobile is placed at the front of the car and is supported on cross members
between the two sides of the car frame. On the Studebaker car, Fig.
416, a sub-frame for the purpose of supporting the rear of the power plant,
the clutch, and the transmission gears has been built in. The power
plant is supported at four points, two at the front and two at the back
of the engine. On the Mitchell car, Fig. 418, the engine is supported
at only three points as indicated. The advantage of the three-point
support is that the engine bearings are relieved of any stress or strain
caused by the engine crankshaft being thrown out of alignment with the
rest of the mechanism, if the frame of the car should be sprung or twisted.
The power plant, clutch, and transmission gears of the Cadillac Eight,
Fig. 419, are built into one unit called a unit power plant. This is sup-
ported at one point in front and two in the rear, thus giving the three-
point support.
The change gears or transmission may be contained as a unit with the
power plant as in Fig. 419, they may be carried amidship as on the Mit-
chell, Fig. 418 and the Pierce Arrow, Fig. 420, or they may be placed
just in front of the rear axle as on the Briscoe, Fig. 421. One objection
to placing the transmission in front of the rear axle is that the gears are
subjected to the continual jolting and jarring due to the rear wheels pass-
ing over rough roads. The most desirable location for the transmission
is as a unit with the power plant as in Fig. 419, or amidship as in Fig.
416.
269. Frames. — The frame is a most important part of the car due
to the fact that it supports the power plant, transmission mechanism,
etc. Consequently, it must be exceptionally strong and at the same time
not too heavy. The frame is made of pressed channel-section steel such
as illustrated in Fig. 422. It is made much deeper at the center than at
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DRAG LINK- ->
SUB FRAME* ^
CONTROL LEVER
BRAKE RODS^
MUFFLER -» _
BRAKE RODS
BRAKES*
DtFFERENT/AL
AND HOUS/NG
- POWER PLANT
ALUMINUM CONE
CLUTCH
.CHANGE GEARS
STORAGE BATTERY
-UNIVERSAL JOINT
-PROPELLER SHAFT
AND TUBE
UNIVERSAL JOINT
- BRAKE RODS
BRAKES
-- GASOLINE TANK
Fio. 416. — Chassis of Studebaker Six.
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THE AUTOMOBILE CHASSIS AND RUNNING GEAR ' 345
the ends in order to withstand the greater bending stresses. The kick-up
at the rear is for the purpose of lowering the center of gravity of the car
and also for allowing greater spring action on the rear springs. The
frame is narrowed at the front in order to permit a shorter turning radius
when steering.
The side members of the frame may be straight and parallel as on the
Ford car, Fig. 423, or the straight members may be tapered toward the
front as in Fig. 421. By tapering the frame at the front, it is possible to
have a shorter turning radius for the car. The taper also permits the use
of a wider body on the frame. This gives a greater seating capacity with
more room. Many frames, as in Fig. 420, have the side members straight
and parallel up to a certain point where the frame is suddenly narrowed.
Fig. 417. — Sectional view of Packard Twin Six car.
Another shape of frame is that of the Studebaker Six, Fig. 416, on which
the frame has a long taper near the center.
In rare cases, frames have been constructed of wood instead of metal.
The wooden frames may be either of solid timber or of laminated strips
glued together and sometimes reinforced by steel strips. The wood
frame is very strong and light and does not transmit so much vibration
as the steel frame. A frame made of second-growth ash and used on the
Franklin car is shown in Fig. 424.
260. Springs and Spring Suspension. — The frame of the automobile
is supported on laminated leaf springs which are directly attached to the
axles. The springs under the frame must be gradual and easy in their
action, and this is why the laminated leaf springs are used. Coil springs
are used only in places where a great deal of strength is needed in a small
space and where quick action is required.
Laminated leaf springs are built up of a series of flat steel plates of
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THE GASOLINE AUTOMOBILE
variable lengths which are placed one on top of the other as shown in
Fig. 425, the longest being on the concave side of the spring. The spring
Fio. 418.— The Mitchell cl
leaves are carefully hardened and tempered. The leaves are held to-
gether by spring clips or a center bolt. The ends of the long leaves are
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THE AUTOMOBILE CHASSIS AND RUNNING GEAR 347
bent around to form eyes by which the spring can be fastened either to
the frame or to another spring. The springs are attached to the axles by
means of clips and spring blocks which are held down on the spring seats
of the axle.
POINT OF
SUPPORT
MUFFLER-
PLATFORM REAR
SPRING SUPPORT^
-POINT OF SUPPORT
UNIT POWER
-- PLANT
POINT OF SUPPORT
-TRANSMISSION
\-t1UFFLER
• TORQUE ARM
^REAR AXLE
GASOLINE TANK
Fio. 419. — Cadillac Eight chassis.
The shape of a spring is a very important item. The main or long
leaf (sometimes called the master leaf) should be comparatively flat,
as this is its natural position and can better take care of road jars and
shocks. The ideal spring is one having long, thin, and flat leaves.
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THE GASOLINE AUTOMOBILE
TRANSMISSION
N
-POWER PLANT
PROPELLER
SHAFT
.BRAKE
EQUALIZERS
Fia. 420. — Pierce Arrow chassis.
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THE AUTOMOBILE CHASSIS AND RUNNING GEAR 349
Fig. 421. — Chassis of Briscoe car.
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350
THE GASOLINE AUTOMOBILE
Fiq. 422. — Channel steel frame used on the Case Six.
■A •
JBk
i ift-=^M84
j@j
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iKfTfli
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Fio. 423. — Chassis of Ford, Model T.
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THE AUTOMOBILE CHASSIS AND RUNNING GEAR 351
As the spring is depressed, the leaves slide on one another. On ac-
count of this fact, some provision must be made for lubricating the leaf
Fio. 424. — Franklin wood frame.
surfaces. This is usually done by forcing grease into specially cut ways
by means of a compression grease cup.
Rebound Clip Spring
I Bushing \ Clip Bolt Clip Cup Retainer
Fio. 425. — Laminated leaf spring.
Leaf springs are built into the following forms for automobile use:
cantilever, double cantilever, semi-cantilever or quarter elliptic, semi-elliptic,
three-quarter elliptic, full-elliptic, platform, and double compounded elliptic.
mi L^fl£
Fio. 426. — Cantilever rear spring.
Cantilever Spring. — The cantilever spring as shown in Fig. 426 is
fastened by shackles to the frame at one end and the center. The other
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THE GASOLINE AUTOMOBILE
end carries the axle. This type of spring reduces the vibration on the
car body because most of the vibration and jar coming from the axle is
taken up by the springboard action of the back of the spring. It is
extensively used as a rear spring. _
Semi-cantilever Spring. — Another type of cantilever spring, Fig. 427,
consists of one-half of a semi-elliptic spring, which has a single rigid fas-
Fia. 427. — Semi-cantilever rear spring.
tening to the frame. It permits very little side sway and is not quite so
springy in its action as a true cantilever. This type is sometimes called
a quarter-elliptic or eeminxintilever, and lias been used for both front and
rear suspension.
Double Cantilever Spring. — The double cantilever spring consists of
two single cantilever springs arranged as in Fig. 428. By using two
Fig. 428. — Double cantilever rear spring.
springs, each may be made lighter and longer, giving an easy riding car.
The springs, as attached to the rear axle, furnish a good method for
taking care of the torque or the tendency of the rear axle housing to
turn over.
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THE AUTOMOBILE CHASSIS AND RUNNING GEAR 353
Semi-elliptic Spring. — The semi-elliptic spring has its center fastened
to the axle, while the two ends support the frame. This type of spring
is generally used to support the front end of the car, because it has the
least amount of side sway. Since the front axle is used for steering pur-
poses, a great amount of flexibility is not desired. Figure 422 illustrates
the use of the semi-elliptic spring for both front and rear suspension.
Three-quarter Elliptic Spring. — The three-quarter elliptic spring, Fig.
429, consists of a semi-elliptic member to one end of which is shackled a
quarter-elliptic member. This type of spring is fastened to the frame at
one end of the semi-elliptic and at the free end of the quarter-elliptic.
The spring is attached to the axle housing at the center of the lower
member. The three-quarter type of spring is generally used at the rear
of the car. The semi-elliptic member is quite long, giving an easy riding
car. When used, the three-quarter elliptic permits of greater side sway
than with either a cantilever or semi-elliptic.
Fia. 429. — Three-quarter elliptic spring.
Full-elliptic Spring. — The full-elliptic spring consists of two sem'-
elliptic springs connected at the ends. The spring is supported on the
axle at the center of one semi-elliptic and it carries the load at the middle
of the other. When used, it is generally employed as a rear spring. Only
occasionally it is found as a front spring. The full-elliptic spring is very
flexible and easy riding, but it has the disadvantage of permitting exces-
sive side sway. The Franklin car uses this type of spring for both rear
and front suspension.
Platform Spring. — The platform spring, Fig. 430, consists of three
semi-elliptic springs shackled together. Two of the members are parallel
to the sides of the car and the third is inverted and is parallel to the cross
members. The car frame is attached to the front end of the side members
and to the middle of the cross member. The middle of the side member
rests on the spring seats. The advantage of this spring suspension is
that whenever one rear wheel encounters an obstruction or goes into a
23
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354
THE GASOLINE AUTOMOBILE
hole, the spring action is taken care of by all three members. Ordinarily,
this action would be taken by the one spring on the same side of the car
±ia. 430. — Platform type of spring suspension.
as the wheel. This equalization of spring action is also evident when the
car goes around a sharp corner very quickly.
Double Compounded Elliptic Spring. — The double compounded
elliptic spring is made up of two long semi-elliptic springs fastened
Fig. 431. — Double compounded elliptic spring.
together at the center as shown in Fig. 431. The ends of the upper spring
are fastened to the frame and the lower spring is shackled to the rear
axle housing. This type of spring permits the use of exceptionally long
Fiq. 432. — Underslung suspension.
leaves. It is used only as a rear spring, and being set back of the rear
axle gives the effect of an increased wheel base. It also reduces the side
sway and twist on the car.
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THE AUTOMOBILE CHASSIS AND RUNNING GEAR 355
Spring Suspension with Underslung Frame. — In most cases the frame
of the car is placed above the springs so as to ride on them. This is
called the overhung method of suspension. When the frame is placed
below the springs so that it is hung from them, as in Fig. 432, the term
underslung is given to this method of suspension.
^ Steering Wheel
'Steering Post
I ^Steering Mechanism
Tjfer V .Drag Link
Tf£8go\
\
- — — ^^ *-' r^?^1
^ — — ---— _
••
n
^K8ll>
Fio. 433. — Case front axle and steering gear.
The underslung suspension permits the use of long springs with the
leaves flat. In addition, the center of gravity of the car is lowered,
bringing the frame members close to the ground, consequently larger
wheels can be used than with an overhung frame.
261. Unsprung Weight. — It is obviously impossible to have the entire
weight of the car supported on the springs. The weight of the wheels,
rims, tires, and in many cases the rear axle is not supported on the springs.
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THE GASOLINE AUTOMOBILE
This weight is usually termed unsprung weight. The car with the least
amount of unsprung weight will have less wear and tear in the tires. The
unsprung weight on any car should be kept down to a minimum.
262. The Front Axle. — The important function of the front axle is to
carry the weight of the front end of the car. A typical front axle assem-
bled with the steering mechanism is shown in Fig. 433. The front axle is
commonly of the I-beam type with either a straight or dropped center.
Left King!
Rn— I Yoke:
"Spring
Seat
Spring
Right King
Pin— I RtftiT
NUCftlt
Yoke
Ak
Left; ^
Knuckle ^— x>«— ^ .
, <J^***^>TZttm Ball
Storing
Arm
¥a*v*
Tie
^vI-Beam FftONT AxlejBv^ight
-^^ Steering
Arm
Fiq. 434. — I-Beam front axle.
The I-beam centers are made either of drop forgings or of cast steel and
are heat treated to do away with brittleness and to give strength and
toughness. The axle yokes are forged or cast integral with the axle
center. The various parts of a typical I-beam front axle are indicated
in Fig. 434.
Fig. 435. — Tubular type of front axle.
It is desirable to have the front axle as low as possible and yet keep
the proper road clearance. The lower the axle can be swung, the lower
the center of gravity of the car will be. The road clearance or the height
of the front axle from the ground is usually about 10 in.
The tubular type of front axle construction, such as shown in Fig.
435, is made from the best high-grade seamless steel tubing. The yokes
are either pinned or brazed on the ends of the tubes. This type of axle is
used very little.
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THE AUTOMOBILE CHASSIS AND RUNNING GEAR 357
263. Steering System. — The steering system of the Cadillac car, Fig.
436, illustrates the method used for steering an automobile. This is
accomplished by having the two front wheels mounted on movable
knuckles which turn in the yokes at the ends of the front axle. These
knuckles are held in the yokes by kingbolts or pins keyed to the knuckles.
The kingbolt is held in place by a nut which is held from coming off by a
cotter pin.
The front wheels are carried on the spindles of the knuckle, and run
on taper roller bearings. The spindles are set so that the front wheels
have a camber of about 2 in., that is, the tops of the wheels are about
2 in. farther apart than the bottoms of the wheels. This is to conform
RIGHT YOKE
AND KNUCKLE
TIE ROD
-STEERING LEVER
ARM
DRAG LINK
"LETT YOKE AND KNUCKLE
Fia. 436. — Cadillac steering gear.
to the crown of the road and to bring the point of contact between the
tire and the road in line with the kingbolt.
The knuckles are free to turn in the axle yokes about 35° either way
from the center line of the axle so as to allow the wheels to follow a curve
when turning. Between the under side of the top arm of the axle yoke
and the top of the knuckle, a taper roller bearing is found. This is to
take the end thrust of the bearing between the knuckle and the yoke.
The angle through which the knuckles can turn on the king pin
determines the turning radius of the car. The turning radius is one-half
the diameter of the smallest circle it is possible to make with the wheels
of the car as in Fig. 437. In order to have a short turning radius, it is
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358
THE GASOLINE AUTOMOBILE
necessary that the knuckle angle be as large as possible and that the frame
be narrowed so as not to interfere with the turning of the wheels.
The steering arms which are usually f orgings are keyed into the steer-
ing knuckles as indicated. The left steering knuckle carries two arms
and the right steering knuckle one arm. If the car has a right-hand
drive, these are reversed.
In order that the front wheels may turn together, the two steering
knuckles are connected, as shown, by a tie rod. This locks the front
wheels together. The tie rod may be either in front or in back of the
axle. The safest location is back of the axle. The steering arm on
the left knuckle is connected by the drag link to the pitman arm of the
steering gear. It is through this pitman arm that the movement of
the steering wheel is transmitted to the steering knuckles and the front
wheels.
Fig. 437. — Turning radius of car.
264u Steering Gear. — There are two general types of non-reversible
steering gear mechanism: the worm and gear and the dovble^worm. In
the worm-and-gear type, shown in Fig. 438, the worm is fastened to the
bottom of the steering tube which is turned by the steering wheel. Mesh-
ing with this worm is the worm wheel which carries the steering lever or
pitman arm. This arm is connected to the drag link which operates the
steering knuckle. The worm-and-gear type of steering mechanism is
non-reversible because the jarring of the front wheels on rough roads can-
not be transmitted back to turn the steering wheel, although the move-
ments of the steering wheel are readily transmitted to the front wheels.
This fact makes the mechanism non-reversible in action.
A modification of the worm-and-gear *type steering gear is the worm
and sector gear shown in Fig. 439. This is essentially the same as the
worm and gear but instead of having a full worm gear meshing with the
worm only a part of a gear or a sector is provided. Some manufacturers
claim an advantage in the worm-and-gear type over the worm and sector
type in that by changing the position of the gear, practically new teeth
can be had to take the place of those which have been worn.
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THE AUTOMOBILE CHASSIS AND RUNNING GEAR 359
'-^ — -
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^^^ MO««*
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Fio. 438. — Worm and wheel steering gear.
Fig. 439. — Worm and sector steering gear.
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360
THE GASOLINE AUTOMOBILE
The double-worm steering gear, illustrated in Fig. 440, has a double-
threaded worm F fastened to the bottom of the steering tube. The
worm meshes with two half-nuts (?, one with a right-hand and the other
a left-hand thread. Two rollers Hf which are attached to the yoke
that operates the pitman arm or steering lever, bear against the lower
ends of the half-nuts. When the handwheel is turned, the tube and worm
turn in the same direction. This causes one half-nut to descend and the
other to rise. This pushes the one roller down and lets the other rise.
The yoke is given the same motion and transmits it to the pitman arm
which pushes or pulls on the drag link, turning the knuckle and wheels.
This type of steering gear is also non-reversible.
Fia. 440. — Double-worm steering gear.
265. Brakes. — Brakes for the purpose of retarding or stopping the car
are usually placed so as to operate on the rear wheels. Each rear wheel
carries a brake drum, a typical example of which is shown in Fig. 441.
The rear axle housing carries two bands, one which fits inside of the drum
and the other on the outside. By contracting the outside band, causing
it to squeeze the outside of the drum, or by expanding the inside band,
causing it to press out on the inside of the drum, the motion of the wheel
is retarded or stopped. This type of brake is called an irdernaLexternal
brake because the braking effect is on both the outside and inside of the
drum.
Usually, the external or contracting brakes are connected by means of
brake rods to the brake pedal in front of the driver's seat. They thus
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THE AUTOMOBILE CHASSIS AND RUNNING GEAR 361
become the service brakes for ordinary braking work. The internal or
expanding brake bands are connected to the emergency brake lever and
act as brakes for emergency purposes. The external-internal braking
system on the Cadillac car is shown in Fig. 442.
Fto. 441. — Rear wheel showing brake drum.
EMERGENCY
BRAKE RODS
Pv^^^j
CONTRACTING BRAKE
^ BAND FOR
A GENERAL SERVICE
EMERGENCY ! ^ s^
BRAKE LEVER \/^m
8T.
^^F* /^-n**
^ ^^P^^^B
y^
r
EXfM&NG BRAKE
BAND FOR
EMERGENCY
ft
*
W^i
" SERVICE B
RODS
RAKE
SERVICE
. BRAKE PEL
)A L
Fig. 442. — Braking system on Cadillac Eight.
All brake bands are faced on the rubbing side with an asbestos or
similar friction material capable of standing a great amount of wear and
not easily burned out. After considerable service this lining must be
renewed to insure perfect braking action.
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362
THE GASOLINE AUTOMOBILE
Two other arrangements of brake bands and drums are shown in Figs.
443 and 444.
service saakk
EMERGENCY BRAKE
SERvlcE BRAKE LEVER
M ■ EMERGENCY BRAKE LEVEH
BRAKE SHOE SPRING
ANNULAR BALL
BEARING iNSJDE
ANNULAR BALL
BEARING OUTSlOC
FULL FLOATING"
AXLE^SMART
Fzq. 443. — Double internal brake with single drum.
, FOOT BRAKE
EMERGENCY BRAKE
ANNULAR BALL BEARINGS
FULL FLOATING
AXLE SHAFT
RELEASE SPRING*
Fra. 444. — Double internal brake with two drums.
In the double internal brake only one wide drum is used. Both bands
are of the expanding type, the outside one serving as the emergency and
the inside one as the service brake. The mechanism for expanding the
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THE AUTOMOBILE CHASSIS AND RUNNING GEAR 363
drums is clearly illustrated. It is known as the cam type. With the
double internal brake, Fig. 444, two drums, a large one and small one,
are used. The brakes are of the expanding type, the large one being
the service brake and the small one the emergency brake.
ADJUST/NO
NUT
BRAKERELEASE BRAKE \ * LOCK NUT
SPRING CAtl ADJUSTING NUT
Fiq. 445. — Brake on transmission.
266. Transmission Brake. — Some cars have in addition to the brakes
on the rear wheels, a brake acting on the transmission or propeller shaft
Fia. 446. — Types of antifriction bearings.
as shown in Fig. 445. The transmission brake is used for emergency
purposes and is used on cars of the heavy type.
267. Effectiveness of Brakes. — With the brakes of proper design and
in good working condition, they should be able to stop a car within the
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364
THE GASOLINE AUTOMOBILE
distances given in the following table. The table has been worked out
on the basis of good average road conditions.
Speed of car
Mfle« per hour
Distance in feet within which brakes
should stop car
10
9
15
21
20
37
25
58
30
83
35
104
40
150
50
230
268. Antifriction Bearings. — In order that the lubrication of the
bearings on the automobile chassis may be reduced to a minimum, anti-
friction bearings are used at the important
a points where bearings of the ordinary rubbing
type would not be practical on account of the
excessive wear which would occur. Bearings
of the rubbing type also require extraordi-
nary care and attention to insure that proper
lubrication is being furnished. Antifriction
bearings when once fitted and installed re-
quire little attention and practically no lubri-
cation. They are, consequently, well adapted
for use at the important bearing points on
the automobile chassis.
Antifriction bearings are of two general
types: ball bearings and roller bearings. The
adaptations of these two types of bearings to
automobile use are illustrated in Fig. 446.
In all antifriction bearings the balls or rollers
are held between the outer and inner races.
The design and construction of the races and
the arrangement of the bearings determine the service for which any
particular bearing may be used. The annular type of ball bearing is
designed to carry a radial load or thrust but is not well adapted to
carry an end load or thrust. An end load or thrust is in a direction
along the axis of the shaft passing through the inner race while a
radial load or thrust is directly down on the bearing in a direction at
right angles to the axis or shaft. The cup-and-cone ball bearing can
Fig. 447.— Hyatt roller
bearing.
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THE AUTOMOBILE CHASSIS AND RUNNING GEAR 365
cany an end as well as a radial
load by having the races con-
structed as shown. The plain roller
bearing is especially well adapted
to carry a radial load, in fact its
carrying capacity is greater than
the annular ball bearings having
the ball diameter same as the roller
diameter. The plain roller bearing
obviously is unable to carry an end
load. When an end load must be
taken a special thrust ball bearing
with side races is used. The taper
roller bearing can support an end
as well as a radial load, and for
this reason is used extensively.
The Hyatt roller bearing, Fig.
447, uses a hollow spiral roller.
This construction gives a certain
springy action which is not found
in the plain solid roller. The
rollers are self cleaning and any
dirt or grit is carried away by the
spiral openings. This Rearing can-
not sustain an axial load. When
used at a point where there is an
end load, a thrust bearing must
also be used.
Figure 448 indicates the various
places on the chassis where anti-
friction bearings are used. The
most important of these are; front
wheels, steering knuckles, change
gears, rear end of propeller shaft,
differential, and rear wheels.
Fig. 448. — Antifriction bearings on chassis.
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CHAPTER XII
CLUTCHES AND TRANSMISSIONS
The power generated by the automobile engine is delivered to the
rear wheels through the power transmission system. This system com-
prises, as may be seen from Figs. 449A and B, the clutch, change gears,
universal joints, propeller shaft, differential, and rear axle.
269. The Automobile Clutch. — The gasoline automobile engine must
be set in motion by external means before it can take up its cycle and
generate power. This fact prevents it from being started under load
and, consequently, means must be provided for disconnecting the engine
from the rest of the power transmission system before the load is thrown
on. The device by which this is done is called the clutch. There are in
use at the present time two general types of clutches, the cone clutch and
the disc clutch.
270. The Cone Clutch. — The principle of the cone clutch is illustrated
by the sketches in Fig. 450. The engine flywheel is turned out so that
the inside of the rim has a taper of from 10° to 12°, and the pressed steel
or aluminum cone of the clutch fits into this tapered ring. This cone is
held tightly in the flywheel by springs, and when it is desired to release
the clutch or disconnect the engine, the foot clutch pedal is pressed
down and the two parts of the clutch disengaged. A brake operating
on the rear end of the cone sleeve prevents it from revolving after dis-
engagement. The cone is faced with some frictional facing such as
leather or asbestos. Spring inserts placed under the friction material
of the cone allow gradual engagement of the chitch and insure the release
of the cone from the flywheel.
A typical cone clutch is illustrated in Fig. 451. It consists of a
leather-faced aluminum cone which fits inside the tapered rim of the
flywheel, and is held by four springs carried on a spider. The aluminum
cone is mounted on a steel sleeve which slides back and forth on the clutch
gear shaft and disengages or engages the cone with the flywheel. A
grooved ring at the rear end of the sleeve connects the clutch to the clutch
pedal. A small brake, attached to the transmission case, serves to keep
the clutch from spinning after it is released. Four small spring plungers,
located under the leather, force it out at four points and prevent grabbing
when the clutch is let in.
367
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THE GASOLINE AUTOMOBILE
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CLUTCHES AND TRANSMISSIONS
369
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THE GASOLINE AUTOMOBILE
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CLUTCHES AND TRANSMISSIONS
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370
THE GASOLINE AUTOMOBILE
Pressure on the clutch foot pedal is transmitted by a connecting link,
to the yoke operating on the clutch release ring which pulls the clutch
Clutch *IN
Fiq. 460. — Principle of core clutch.
back out of engagement with the flywheel. The small brake now holds
the clutch stationary, while the clutch spider and springs continue to
Ffywheet
Clutch leather
Clutch cone -\
Clutch release
r/ng
Transmission
cose -
Clutch qear--*\
shaft J
Clutch brake -*
Clutch thrust bearing
Clutch spring
I Crank shaft
(
fta. 461. — Typical cone clutch.
run with the flywheel until the clutch is again engaged. When in full
engagement, the clutch and flywheel turn as a unit, transmitting the
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CLUTCHES AND TRANSMISSIONS
371
power through the change gears to the rear axle. There are no
adjustments to be made on this clutch. When the facing on the cone
becomes so worn that the clutch does not operate satisfactorily, it is
necessary to put on a new facing.
The cone clutch with leather facing generally runs dry, that is, it
does not run in an oil bath. The leather facing must be prevented from
becoming hard by dressing it with neats-foot or castor oil which will
keep it soft and pliable. Continued use of the clutch causes the leather to
become hard. If the clutch slips on account of oil or grease getting on the
leather facing, the leather should be cleaned with gasoline and a small
amount of finely ground fuller's earth, which is an earthy substance resem-
bling clay, placed on it. Although the cone clutch with an asbestos or
fabric facing usually runs dry, some types are run in an oil bath. If the
oil becomes thick and gummy, causing the clutch to stick, it should be
thoroughly cleaned out with kerosene and new oil put in.
Fiq. 452. — Cone clutch with spring inserts on flywheel.
A cone clutch with spring plungers on the flywheel instead of on the
cone is shown in Fig. 452. The facing is on the cone and while being
engaged the plungers prevent the cone from grabbing. These plungers
also prevent sticking when the clutch is being released.
271. The Disc Clutch. — The disc clutch consists of a series of flat
friction plates or discs held together by a spring as illustrated in Fig.
453. Each alternate plate or disc is attached to the flywheel and these
drive the other plates which have a connection to the change gear set.
The power is transmitted through frictional contact of the sides of the
plates. This type of clutch gives a large frictional surface with a com-
paratively small clutch diameter, while on the cone clutch, the diameter
must necessarily be large in order to give the necessary frictional surface.
The disc clutch may use as few as three plates or it may use a great many.
The disc clutch may also be run dry, in which case it is called a dry
plate clutch, or it may be run in an oil bath, when it is called a wet plate
clutch.
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THE GASOLINE AUTOMOBILE
Fia, 453. — Dry-plate typo of clutch.
Fig. 454. — Borg and Beck single plate dry-disc clutch.
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CLUTCHES AND TRANSMISSIONS
373
The Borg and Beck type of single plate dry disc clutch is illustrated in
Fig. 454. The casing of the clutch is cast with the flywheel to which is also
directly attached the two asbestos friction rings. The friction ring on
the side of the plate away from the flywheel is carried by a thrust ring
which receives the thrust of the coil clutch spring through a bell crank
lever. When the clutch is in, the single plate is held between the two
friction rings, locking the whole mechanism which then turns with the
flywheel. When the clutch is released by the foot pedal, the pressure of
the friction rings on the plate is released and the spinning of the plate
is prevented by the clutch brake. When released, all parts of the clutch,
HAND BRAKE
LEVER
; COUNTERSHAFT
\ DRIVE GEAR
OWING CLUTUi
DISC RELEASE
bfiMNGD/SCP/N
\ COUNTERSHAFT LOW
\ 6REVERSE PfNfONS
HIGHSPEED INTERNAL
GEAR
TRANSfltSSW DRAIN PLUG
^CLUTCH DRAIN
PLATE
Fig. 455. — Dodge multiple-disc dry-plate clutch and transmission.
with the exception of the plate, its shaft, and the brake collar, continue
to turn with the flywheel. It is very necessary that the clutch release
bearing be well lubricated, as this bearing carries a heavy load when the
clutch is released.
The multiple-disc dry-plate clutch used on the Dodge car, Fig. 455,
consists of seven discs held together by a heavy coiled spring. Four of
the discs are carried on the flywheel by six pins, and the other three are
carried by three pins riveted to the clutch spider which is keyed on the
clutch shaft. The four driving discs on the flywheel are faced with a wire
woven asbestos fabric, while the three driven discs are plain. The clutch
is released by pushing on the left foot pedal. This presses the clutch
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374
THE GASOLINE AUTOMOBILE
release yoke against the clutch release which forces the clutch hub and
pressure plate back. This releases the spring pressure from the clutch
disc, allowing the driving discs to turn free from the driven ones. The
clutch release is lubricated through the clutch release grease tube shown.
The Cadillac multiple-disc dry-plate clutch, Fig. 456, has nine plain
steel-driven discs and eight driving steel discs faced on both sides with
an asbestos friction fabric. By attaching the friction material to the
driving discs rather than to the driven discs, unnecessary and undesirable
weight is thereby avoided in the latter, thus decreasing the tendency to
%
GEAR SHIFT
■ ■—LEVER
ROLLER BEARINGS
SUPPORTING tl A! N SHAFT
OF TRANSMISSION
1
Fig. 456. — Cadillac clutch and transmission.
spin when the clutch is released. A coil spring under 300 lb. com-
pression furnishes the pressure for forcing the driving and the driven
discs tightly together. This spring is held within the clutch hub, the
splines on which are a sliding fit in the keyways ant in the driven discs.
The clutch is released by pressure on the clutch peo^; the leverage being
compounded to produce the desired result. \
The wet-plate clutch is constructed on the samA general principles
as the dry-plate clutch. The essential difference in Operation is that it
runs in a bath of oil or lubricating oil mixed with kefosene. When the
clutch is released, an oil film covers the entire surf ac J of the plates, and,
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CLUTCHES AND TRANSMISSIONS 375
when the clutch is thrown in, this film of oil is gradually squeezed out,
permitting a very easy and gradual engagement. In the winter time,
the oil may get unusually heavy thus preventing quick engagement of
the clutch. This can be overcome by thinning the clutch oil with
kerosene.
In some types of plate clutches, the plates are punched and cork
inserts are pressed into the holes. These inserts permit an easy and
gradual engagement of the clutch even if the plates should become
coated with oil.
272. Operation of Clutch. — When the car is started, the clutch
being out, the gears should be shifted into low and the engine speeded
up but not raced. The clutch should then be let in gradually by releas-
ing the pressure of the foot on the foot pedal. It is not desirable to slip
the clutch any more than necessary as this means excessive wear on the
clutch parts. It is the practice of some drivers to keep a light pressure
with the foot on the clutch pedal at all times. This results in a more or
less slipping of the clutch and a consequent extra wear on the clutch parts.
273. Change Gear Sets. — The change gear set or the transmission as
it is customarily called is for the purpose of permitting different speed
ratios between the engine and the rear wheels of the car. When the car
is being started from rest, it is necessary to have considerable power
delivered to the rear wheels which are moving at slow speed. If it was
necessary to also run the engine at slow speed while starting the car,
very little power would be delivered to the rear wheels, because the auto-
mobile engine does not deliver its maximum power at slow speed. It
might be possible to speed up the engine and then endeavor to start the
car by throwing in the clutch, but this would result in the slowing down
and perhaps stopping of the engine when the heavy load was suddenly
thrown on. The change gears make it possible to change the speed
ratios of the engine and rear wheels so that when the car is being started,
the engine can be run fairly fast and yet be able to pick up the load which
comes to it through the gears of the transmission.
The change gear transmission used on the Cadillac is illustrated in
Fig. 456. The teeth of the driving gear are cut on the end of the clutch
shaft which turns when the clutch is engaged, but remains stationary
when the clutch is out. The countershaft carries four gears which are
fixed to the shaft and revolve with it. The main shaft of the trans-
mission fits into the clutch shaft and is supported by the roller bearings
shown. The transmission shaft carries two sliding gears which can slide
along the shaft but which cannot turn unless the shaft also turns. This
shaft is connected to the propeller shaft leading to the rear axle. The
shifting of these gears along the shaft is done through the gear shift
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376
THE GASOLINE AUTOMOBILE
lever which controls the two gear yokes on the gears. Figure 457 indi-
cates the various positions of this lever.
The driving gear on the clutch shaft and the large gear on the counter-
shaft are always in mesh. This means that whenever the clutch is in,
the driving gear and also the four gears on the countershaft will be
turning. The countershaft gears will be turning in the opposite direction
to the driving gear. In the position shown the gears are out of mesh and
are said to be in neutral and even though the clutch were in, no motion
would be given to the main shaft of the transmission. The countershaft
and gears would be turning idle.
If the gear shift lever be pulled to the position indicated under low,
gear G will be meshed with gear H on the countershaft. Power will
then be transmitted as indicated by the arrows under first speed, in Fig.
458, which represents a similar change gear set. When in low, the clutch
shaft turns from 2^£ to 3 times as fast as the transmission shaft which
NEUTRAL TO LOW
LOW TO INTERMEDIATE
INTERMEDIATE TO HI OH NEUTRAL TO REVERSE.
Fio. 457. — Positions of gear shift lever for transmission speed.
drives the propeller shaft leading to the rear axle. The exact speed ratio
depends upon the number of teeth in the gears.
If the car is running in low gear, the gear shift lever, by first releasing
the clutch, can be shifted from the low to the intermediate position,
Fig. 457. This will shift gear G out of mesh with gear H and put gear
F into mesh with gear I. After engaging the clutch again the power is
transmitted as indicated by arrows under second speed, Fig. 458. It will
be noticed that gear F is smaller than gear G and that gear I is larger than
gear H . For this reason the transmission shaft runs faster in comparison
to the countershaft than in low speed. The clutch shaft and also the
engine now turns only about 1.75 times the speed of the propeller shaft.
By releasing the clutch and changing the lever from the intermediate
to the high position, gears B and F are locked together by side or clutch
teeth, as in Fig. 458, or by the meshing of the teeth of a small geariT,
attached to gear B, into internal teeth cut in F. When in this position,
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CLUTCHES AND TRANSMISSIONS
377
Fia. 458. — Positions of gears in three-speed-and-reverse gear set.
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378 THE GASOLINE AUTOMOBILE
the engine and propeller shaft turn at the same speed, the power being
transmitted directly through gears B and F. The countershaft merely
runs idle. This is the running position for the gears and they need only be
shifted when it is desired to stop, reverse, go up a hill, or accelerate after
the car has been running very slowly.
The car can be reversed after being brought to a stop by shifting the
gear lever first into the neutral and then into the reverse position, Fig.
457. This brings gear G into mesh with the reverse idler gear L shown in
Fig. 458. This idler gear now being in mesh with both gears G and J,
these revolve in the same direction. This means that G and, conse-
quently, the propeller shaft revolve opposite in direction to the gear B
and to the engine. The speed ratio of the engine and propeller shaft
on reverse gear is about 3.5 to 1.
This type of transmission is called a selective sliding gear set because
it is mechanically possible to shift immediately from one gear position
to any other position. In some types of gear sets, it i$ mechanically
possible to change gears only in a definite order, that is, reverse, neutral,
low, intermediate, and high, and back in the same order, rhis type is
called a progressive transmission. It is not used to any extent because of
the almost universal adoption of the selective transmission in which it is
possible to select the gear position at will.
In a few cases, more than three forward speeds are provided for in
the transmission. Instead of having only & first, second, and third speed,
a fourth speed is added. The direct drive is on fourth speed. The four
speeds are usually found only on large heavy cars where it is thought
three speeds are not adequate.
274. Operation of the Gear Set — In order to operate a car properly,
considerable skill in handling the engine, clutch, and change gears is
necessary. The engine having been started with the change gears in
neutral, the clutch must be disengaged before the gears can be shifted
into low. After the gears are in mesh, the clutch must be let in gradually
in order to prevent stalling or killing of the engine. While the clutch is
being engaged, the engine should be speeded up to assist in accelerating
the car. The engine should not be raced nor the clutch slipped for any
considerable time as this will result in excessive wear. In changing
from low to intermediate or from intermediate to high, the clutch must
be released before the shift to the higher gear is made. It is often found
that a pause in neutral when shifting gears will assist in meshing the
gears without grinding or clashing. It may be found advisable to slow
down the engine slightly while shifting gears, and to open the throttle
just as soon as the clutch is in.
When it becomes necessary to change from a high to the next lower
gear this can be accomplished by releasing the clutch, shifting to neutral,
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CLUTCHES AND TRANSMISSIONS
379
speeding up the engine somewhat, and then putting the gears into the
next lower position. The aim is to have the gears revolving at the same
speed so that they will mesh easily. In shifting the gears into reverse, it
is necessary that the car first be brought to a
stop. The shift into reverse gear sfiould never be
made with the car moving forward
276. Lubrication of the Transmission. — The
change gears should work preferably in a soft
gear grease or heavy oil. A graphite grease has
also been used for this purpose. The lubricant
should follow the gear teeth when operating and
should never become hard enough to resist flow-
ing. It should be thoroughly cleaned out and
replaced about every 2000 miles of service.
276, Gear Shift Levers. — The type of gear
shift lever illustrated in Figs. 455 and 456 is of the ball-and-socket type
while that in Fig. 459 is of the gate type. The positions of the shift lever
for the different gears are not the same for all make3 cf ball-and-socket or
Fig. 459. — Gate type of
gear shift lever.
Fig. 460. — Positions of gear shift lever on Dodge car.
gate-type levers. The lever positions for the transmission in Fig. 455
correspond to Fig. 460 while those shown in Fig. 461 are just opposite.
Both arrangements are used extensively.
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380
THE GASOLINE AUTOMOBILE
277. Location of Transmission. — The transmission may be built into
a unit power plant with the engine, may be placed independent of and
immediately back of the engine, may be midway
REVERSE jJ^jMATE ketween the engine and rear axle, or may be placed
\ NEUrRALfd
iLil yfe~ — »*»
at the rear axle. When the unit power plant is
used, universal joints, one at the front and one
at the rear of the propeller shaft, are used. If the
gears are placed separate just back of the engine,
only one universal joint need be used. One objec-
tion to placing the gears at the rear axle is that
the transmission is subjected to all of the jars and
jolts from the rear axle when the car is running
over rough roads or other rough places.
278. The Planetary Transmission. — The plane-
£f tary transmission, as used on the Ford car, com-
bines the clutch and change gears into a single com-
pact unit. It provides two forward speeds and a
reverse. The gears are not shifted for the different
speeds as in a sliding-gear transmission but re-
main meshed together. The planetary transmission is so named be-
cause certain gears called the planet gears revolve about other gears
Fig. 461. — Positions
of gear shift lever for
Overland car.
(CLUTCH PEDALl
(REVERSE BAND)
CLUTCH LEVER^
SCREW
CLUTCH STOP
.(CLUTCH BAND)
T
>AKE BAND)
^\ ^CLUTCH SPRING
Fiq. 462. — The Ford planetary transmission.
called the sun gears just as the planets revolve about the sun. An
assembled view of the planetary transmission is shown in Fig. 462, a
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CLUTCHES AND TRANSMISSIONS
381
sectioned view in Fig. 463, and a view of the disassembled parts in Fig.
464.
Fig. 40;i. — Internal construct ion of planetary transmission.
DRIVING Y
iPLAtt
CLUTCH DRIVING
SPRING STOP PLATE
Fig. 464. — Disassembled view of Ford planetary transmission.
The engine flywheel A carries the shaft B and also the three pins
D spaced equally around the flywheel and fixed to it. The triple gears
fit over these pins. The triple gears consist of three gears: E with 27
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382
THE GASOLINE AUTOMOBILE
teeth; F with 33 teeth; and G with 24 teeth. These three" gears are
pinned together and turn as a unit on pins D.
Gear K with 27 teeth fits over the shaft B and meshes with the three
gears E of the triple gears. All four of these gears (E, E, E, K) have the
same number of teeth (27). The brake drum T which carries the sleeve
N fits over shaft B, and the gear K is keyed to sleeve N. Brake drum S
is attached securely to sleeve 0 which has cut on its end the gear / of
21 teeth. . This gear L meshes with all three gears F which have 33 teeth
each. Gear L is smaller than the gears F by 12 teeth. The drum R with
its attached gear M slips over sleeve 0, and gear M of 30 teeth meshes
with all the gears G with 24 teeth each. Gear M is larger than gear G
by 6 teeth.
Fiq. 465. — Ford control showing hand lever for operating clutch stop.
The brake drum T houses the disc clutch of the transmission. Every
other disc F, Fig. 463, is attached to the drum T which in turn carries
the sleeve N and the gear K. The alternate clutch discs U are carried by
the spider V fastened to shaft B which turns with the flywheel. The
drum T is fastened to the driving plate which is keyed to the propeller
shaft C. This driving plate has three clutch fingers X which, because of
the pressure exerted on them by the clutch shift and spring W, force the
plates Y and U together, thus engaging the clutch. The clutch spring
W is held on the shaft C by the clutch spring stop.
By referring to Fig. 462 the construction and placing of the operating
bands, pedals, and levers can be seen. Pedal R and its connections make
it possible to tighten the friction band around the drum R. Likewise,
pedals S and T cause the bands S and T to be tightened around the drums
S and T. A connection is made between the pedal S and the clutch
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CLUTCHES AND TRANSMISSIONS 383
shift ring so that when clutch pedal S is pushed down, the shift ring
compresses the spring W and releases the clutch plates. The clutch
stop, Fig. 462, is under the control of the driver through the hand lever
in the car and holds the clutch out when the hand lever, Fig. 465, is in an
upright position. This throws the stop immediately under the clutch
lever screw.
279. Operation of Planetary Transmission. — When the engine is not
running and the car is still, the hand lever is in the upright position with
the stop immediately under the dutch lever screw, thus preventing the
disc clutch from being engaged. With this position of the hand lever
the clutch pedal S is held in the neutral position between its extreme
forward and extreme backward positions. Under these conditions, the
clutch band S cannot be tightened around the drum S.
After the engine is started, the flywheel causes the shaft B, the spider
V, and the plates U to revolve in the same direction and at the same
speed as the engine. The triple gears are carried around by the pins D.
Gear K being fastened to sleeve N and to drum T is held stationary
because drum T is attached to the driving plate which is keyed to the
propeller shaft C. This throws the resistance of the car on gear K and
holds it stationary, because in order for K to revolve, the shaft C must
also revolve and the car must move. Gears E being meshed with gear
K must revolve on pins D as will also the gears F and Gf these three
(E, F, G) being fastened together. Gears F and G revolving on pins
D mesh with gears L and M . These gears L and M are free to turn
because they are attached to drums R and S which are free to move
inside of the bands around them, and revolve in a direction opposite
to the flywheel of the engine.
Low Gear. — Preparations for starting the car are made by first throw-
ing the hand lever, Fig. 465, forward and also by preventing the clutch
pedal from coming back by holding it in neutral position with the foot.
The disc clutch is still disengaged. By pushing the clutch pedal full
forward the band S grips the drum S tightly and prevents it from re-
volving. This drum S (now held stationary) being connected to sleeve
O prevents gear L with 21 teeth from turning and, consequently, it is
held stationary. The flywheel revolving, causes the pins D to revolve
in a circle. The fact that gear L with 21 teeth is held stationary causes
gears F with 33 teeth each to turn about pins D as axes. By referring to
Fig. 466 the relative motion of these gears can be seen. Gear L with 21
teeth is held stationary while the flywheel causes pins D to move in a
circle. This causes gears F to revolve on pins D. Only one of the F
gears is shown as the action of the other two is identical. Let it be as-
sumed that gear F is vertically above gear L as shown and that the fly-
wheel causes pin D to move through 90° or one-quarter of a revolution.
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384
THE GASOLINE AUTOMOBILE
This means that gear F has revolved on pin D the part of a revolution
corresponding to one-quarter of the number of teeth on gear L or 5)^
teeth. Gear F has 33 teeth so in position (2) gear F has turned on D
5 25
only -j^T- or a little less than % of a revolution. In position (3) gear F
has made slightly less than % revolution on D; in position (4) slightly
less than \i revolution; and when the flywheel has made one complete
revolution, gear F has made only 2^3 or about % of a revolution on
pin D. In other words, F is turning on D about % as fast as the engine
flywheel and in the same direction. Practically, this means that in
relation to the flywheel, gear F has been turned backward on D about %
revolution, each time the flywheel revolves once. Gear E being fastened
to F also must turn back on D about J^ revolution for each revolution
of the flywheel. If gears E, Fig. 463,
with 27 teeth are turned back on D
\i revolution for each revolution of
the flywheel, gear K with the same
number of teeth must be moved
around in the direction of the fly-
wheel % revolution, or ^ as fast as
the flywheel. Gear K being attached
to the drive shaft C through sleeve N,
drum r, and the driving plate, causes
the propeller shaft of the car to re-
volve at approximately J^ engine
speed and in the same direction. This
is the method of operation when in
low gear.
High Gear. — After the car is under way, the transmission can be
put in high gear by removing the pressure from the clutch pedal, thus
allowing it to come into its full backward position. This releases the
low-speed brake band S and also throws the disc clutch in. If the hand
lever in the car had not been thrown forward, the stop would have pre-
vented the clutch from being engaged. When in high gear, all the bands
are loose on the drums and they are free to revolve. The flywheel
drives the triple gears E, F, G, through the pins D. The triple gears
cannot revolve on the pins D because triple gears J? are in mesh with K
which has a direct connection with the propeller shaft C because the
clutch is in. This means that the entire mechanism (planetary gears,
sun gears, drums, and clutch) is locked together and turns as a single
unit in the same direction and at the same speed as the engine. The
propeller shaft and engine also turn at the same speed.
Reverse Speed. — Before the transmission can be thrown into reverse
Fio. 466. — Relative motion of planetary
gear F and sun gear L on slow speed.
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CLUTCHES AND TRANSMISSIONS
385
gear, the clutch pedal must be held in neutral position by the foot, or
the hand lever must be in its vertical position which would also hold the
clutch pedal in neutral and hold the clutch in the disengaged or out
position. All bands are free on the drums. By pushing the reverse'
pedal R full forward, the band R grips the drum R and causes it and the
gear M, to which the drum is attached, to be held stationary. The
flywheel causes the triple gears to revolve with it and also causes gears
G with 24 teeth each to turn on pins D, in mesh with gear M of 30 teeth.
The condition now is as shown in Fig. 467. Gear G with 24 teeth is
meshed with gear M , 30 teeth (held stationary) and is turning on it in
the same direction as the flywheel. When pin D has moved through
90°, or one-quarter revolution, gear G has turned on pin D that part of
a revolution corresponding to one-
quarter of the teeth on M or 7 J^ teeth.
Gear G has thus turned on
D &
24
Fig. 467. — Relative motions of plane-
tary gear G and sun gear M on reverse
speed.
or about % revolution. When the
flywheel has completed % revolution,
gear G has completed about % revolu-
tion on D, and when one complete
revolution has been completed by the
flywheel, gear G has turned about 8%4
or 1 V£ times on its pin D. Practically,
this means that in relation to the fly-
wheel, gear G is moved ahead }£
revolution for each turn of the fly-
wheel. It can be seen from Fig. 463
that if gears G be turned ahead or in
the direction of the flywheel, gears E must also be turned ahead. This
results in gear K being driven in the opposite direction to gears E and also
to the flywheel, at practically 34 engine speed. The power is trans-
mitted through sleeve N, drum T, and the driving plate to the propeller
shaft C.
The brake pedal when pushed down causes the brake band to tighten
on drum T. This acts as a service brake for the car. The service
brake shoulcl never be applied while the car is in full slow, full high gear,
or full reverse, as this causes undue wear and strain on the parts. The
reverse pedal should never be pressed down unless the clutch pedal is in
neutral, as this will result in a serious damage to the transmission.
Advantages of Planetary Gearing. — The advantages of this type of
transmission are that it is compact, can be controlled by the feet, and
that the gears are always in mesh and need not be shifted at any time.
The planetary gearing is extremely noisy when running in low gear and
25
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386
THE GASOLINE AUTOMOBILE
reverse, as all of the gears are turning. When in high gear all the gears
turn as a unit, giving a quiet running and compact mechanism. It is
almost impossible to have more than two speeds forward with this type
' of transmission on account of the complexity of the gearing. This limits
its use to small and light cars.
280. Universal Joints and Propeller Shaft. — In transmitting the
power from the engine or transmission to the rear axle, it is necessary
couture gwvensAL-joiMT
Fig. 468. — Propeller shaft with two universal joints.
that some kind of a flexible connection be used because the propeller
shaft is usually not in a straight line with the crankshaft of the engine.
The rear axle is placed lower than the engine and this means that power
must be transmitted at an angle to the rear axle. This is made possible
by the use of one or more universal joints, Fig. 468, which are practically
double-hinged joints. A universal joint consists of two yokes or forks
both hinged to a crosspiece of block between them as in Fig. 469. Each
Fig 469. — Blood universal joint.
Fig. 470. — Thermoid flexible con-
nection on Crow Elkhart car.
yoke then has a hinged motion at right angles to the other yoke. By the
use of a universal joint, power can be transmitted at any angular direction
with a very small loss of efficiency.
One, two, or three universal joints may be used in the transmission
system. With a unit power plant, it is customary to use two, one at each
end of the propeller shaft, although in some cases only one at the front
of the shaft is used. The exact number depends upon the arrangement
of the transmission and propeller shaft.
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CLUTCHES AND TRANSMISSIONS
387
In addition, the universal joint takes care of the jars and shocks from
the rear axle which tend to throw the propeller shaft out of line. Without
these flexible connections, it would be impossible to have a spring action
between the rear axle, and the engine and transmission of the car.
Fio. 471. — Hollow propeller shaft.
281. Lubrication of Universal Joints. — The universal joints are
either run open, or are encased in a leather cover strapped around the
joint. With the open type, the cross pins are usually lubricated with
grease cups, while in the closed type the
leather cover is filled with a grease which
surrounds and lubricates the pins.
282. Flexible Couplings. — The usual type
of universal joint is sometimes replaced by
the use of a flexible connection, as shown in
Fig. 470. The angular movement permitted
by this connection is due to the flexibility of
the leather or fabric discs in the connection.
The use of the flexible type of universal con-
nection is becoming more general, although it
is not generally considered so satisfactory as
the usual type of universal joint.
283. Propeller Shaft.— The propeller or
drive shaft may be either of the solid or of
the hollow tube type as in Fig. 471. The
hollow tube type gives a maximum of strength
with a minimum weight. The propeller shaft
may run open or it may be enclosed in a hous-
ing which keeps it away from dirt and possible
damage. Figure 472 shows the trunnion joint
connection at the front of the casing surrounding the solid propeller
shaft used on the Paige car. Such a casing around the propeller shaft
also helps to take care of the torque action of the rear axle.
Fio. 472.— Trunnion joint
connection at front of propeller
shaft casing on Paige car.
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CHAPTER XIII
REAR AXLES AND DIFFERENTIALS
The power delivered by the engine through the clutch and trans-
mission gears to the propeller shaft is made available at the two rear
wheels by transmitting it through the rear axle. The general method of
doing this is illustrated in Fig. 473. The power is delivered to the rear
axle by the final drive, which consists of two gears. The small gear is
fastened to the propeller shaft and is called the driving pinion. The
large one is fastened to the rear axle and is called the ring gear. The
power is transmitted from the propeller shaft to the rear axle through
JD*J(/5T/MG Mt/T I OCK-
P/N/ON SMFT BEXR/NGS
o/ieR.
DRUM
I Q/rf£RENTfAl tt0i/S/W6
swi£ s/fs?rr
Fia. 473. — Live type of rear axle.
the driving pinion which drives the ring gear and, consequently, the
rear axle.
284. Final Drives. — Three types of gearing have been employed for
the final drive between the propeller shaft and the rear axle. These
are the bevel, spiral-bevel, and worm gearing.
The bevel gear final drive, Fig. 474, consists of two plain bevel gears
with straight teeth, meshing together and changing the direction of the
power through a right angle from the propeller shaft to the rear axle.
The size of these gears and the number of teeth in each regulate the speed
ratio of the propeller shaft and the rear axle. This ratio is usually
such that the propeller shaft will make from 3 to 5 revolutions to one
of the rear axle. The number of teeth on one of the gears is usually odd,
such as 21 or 23, while the number on the other is usually even, such
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390
THE GASOLINE AUTOMOBILE
as 60 or 62. By this arrangement, the odd tooth, which is called the
hunting tooth, meshes at times with all of the teeth on the other gear,
thus causing the same amount of wear on all teeth of the two gears. The
straight tooth bevel gears have the disadvantage that there is sometimes
considerable lost motion or backlash between the teeth causing them to
be very noisy. This difficulty has been overcome to a large extent in
the spiral-bevel type of final drive.
A final drive using spiral-bevel gears with the spiral or curved teeth
is illustrated in Fig. 475. The spiral-bevel gearing gives a more continu-
ous contact between the teeth, and prevents the possibility of the exces-
sive backlash or lost motion, which is sometimes found between plain
DIFFERENTIAL PINION
PINION SPIDER
DIFFERENTIAL GCAA
BEARING LOCK RING
AXLE HOUSING
*tAR CARRIER CAP
Fia. 474. — Bevel gear final drive.
bevel gear3 after considerable use. The spiral-bevel final drive is quiet
when operating and in general is more satisfactory than the plain spiral
gear drive.
The worm type of final drive employs a worm for driving the worn
gear on the rear axle. This worm may be placed either above or below the
worm gear. Figure 476 illustrates a worm drive with the worm placed
above the gear. This type of final drive is very quiet running and effi-
cient, but requires very good lubrication because of the constant sliding
action between the worm and gear. One of the two should run in an oil
bath. The worm is usually made of steel and the gear of bronze in order
to keep down excessive friction and wear. The worm final drive permit*
a very large speed reduction and is, consequently, well adapted to truck
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REAR AXLES AND DIFFERENTIALS
391
and other slow speed heavy service. Figure 477 is a view of the worm
final drive used on the Ford Model T Truck.
286. Bearings for Final Drive. — On account of the fact that there is
a thrust between the gear teeth, tending to separate them, it is necessary
that proper bearings be provided to take up the thrust and at the same
time hold the gears in place. Usually the bearings are of the ball or
tapered roller type because these can sustain both the end and side thrusts
which come on the gears. A plain roller bearing alone could not answer
the purpose because it cannot withstand
both a thrust along its axis and one at
right angles to it. In the bevel gear drive
of Fig. 474, the thrust is taken care of by
ball bearings. These prevent both end and
side movement of the driving pinion and
the bevel gear. The use of tapered roller
bearings is illustrated in Fig. 475. Being
fi
Miii<
Fio. 475. — Spiral-bevel gear type
of final drive.
Fio. 476. — Worm type of final drive.
tapered, they give all the advantages of a roller bearing and also the
feature of a ball bearing in being able to carry an end thrust as well
as a side pressure.
286. Types of Rear Axles. — There are two general types of rear
axles, the dead rear axle and the live rear axle. The dead rear axle is
similar to that used on wagons and buggies. It is made solid with the
wheels turning on spindles on the axle end. This type of axle is used
only on heavy trucks and other commercial cars where it is necessary to
have a solid construction and at the same time provide for a large reduc-
tion in speed.
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THE GASOLINE AUTOMOBILE
In the live type of rear axle, the axle proper turns inside of a sta-
tionary housing and transmits the power to the rear wheels to which the
axle is attached. The axle housing supplies the bearing for the wheels
and axle and also supports the car through the springs. The main func-
tion of the live axle is to transmit power and not to support the weight
of the car as in the dead axle. The live axle is divided in the center, each
half being fastened to one of the rear wheels. Live rear axles are classified
according to the method of construction, as simple, semi-floating, three-
quarter floating, and full floating.
287. Simple Live Rear Axle. — The simple live rear axle, in addition
to transmitting the power to the rear wheels, also supports the entire
weight of the rear of the car. The rear axle used on the Ford car, Fig.
478, illustrates a typical simple axle. The axle shaft is carried both at
Fio. 477. — Worm final drive on Ford Model T truck.
the center and at the wheel ends by roller bearings which- in turn are
supported by the axle housing. The rear wheels are keyed to the axle
shafts as shown. The entire weight of the rear of the car is carried on the
axle shaft which also revolves and transmits the power to the wheels.
Any stress due to the skidding of the car or the wobbling of the wheels
must also be taken care of by the axle shaft. The side thrust of the
driving pinion is taken care of by the straight roller bearings, while ball
bearings support the end thrust. The end thrust of each half of the axle
shaft is taken care of by the three metal thrust washers. The straight
tooth bevel gear final drive is employed with this axle.
288. Semi-floating Rear Axles. — The essential difference between a
simple live axle and one of the semi-floating type, Fig. 479, is in the fact
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REAR AXLES AND DIFFERENTIALS
393
that in the latter type, the inner bearings, supporting the axle housing and,
consequently, considerable weight, are carried on an extension of the
differential case, instead of being carried by the axle shaft itself. This
I'1 .
tutu
inn
ilten
relieves the shaft of considerable stress due to the weight carried. The
wheels are keyed to the axle as in the simple type and the outer bearings
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394
THE GASOLINE AUTOMOBILE
are also on the shafts. This throws the stress, due to skidding and
turning corners, on the axle. If an axle shaft should break or twist off
the wheel would come off. It is impossible to remove the axle shaft
with the wheel on the car.
'POWER FROM
DRIVE SHAFT
LINE AXLE
SHAFT
P
AXLE HOUSING
^SHAFT BEARINGS'
DRIVING
^PINION
:bevel ring
^DIFFERENTIAL
Fio. 479. — Studebaker semi-floating rear axle.
289. Three-quarter Floating Axle. — In this type of axle, an outer end
of which is shown in Fig. 480, the wheel is supported by a single bearing
carried on the axle housing. This bearing is placed directly under the
480. — Outer end of three-quarter floating axle.
center of the wheel thus relieving the axle shaft of all stress due to the
weight of the car. The wheel is keyed onto the shaft as in the simple and
semi-floating types. On account of this rigid connection between the
axle shaft and wheel, and also because the wheel is supported by a single
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REAR AXLES AND DIFFERENTIALS
395
bearing, the stresses and strains due to a possible side movement of the
wheel, or due to distortion from a bent housing, are still thrown on the
axle shaft. Although the shaft carries no part of the weight of the car,
yet it is still subject to many bending and twisting strains. If the axle
Fia. 481. — Full floating rear axles.
shaft should break on either a simple, semi-floating, or three-quarter
type of axle, the wheel can come off and let the car drop. This can be
prevented only by the full-floating construction.
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396 THE GASOLINE AUTOMOBILE
290. Full-floating Rear Axle. — In this type of construction, as illus-
trated in Fig. 481, the wheels are carried by a double ball or roller
bearing on the axle housing in such a way as to retain the wheel on the
housing regardless of what may happen to the axle shaft. The axle shaft
has only to transmit the power and is not subject to the stresses and
strains due to skidding and turning corners. These are taken care of by
the axle housing. The live shaft can be removed and replaced without
taking the wheel off or disturbing the differential. The inner end of
the axle shaft is grooved and fits into corresponding grooves in the dif-
ferential. The shaft is removed by removing the hub cap and sliding
the shaft out. Some types of axles are called full-floating when the wheel
is carried by two bearings on the housing and when the wheel is keyed
onto the axle shaft. Strictly speaking, an axle is not full floating if the
wheel is keyed onto the shaft, as there is still the possibility of stress and
strain being thrown on the shaft by a distortion of the housing, resulting
in a slight side movement or wobbling of the wheel. A true full-floating
Full Fleeting Axle Shift
i
Fixed Huh AxU Shalt
Fig. 482. — Axle shaft for full-floating and fixed hub rear axles.
axle is one in which the connection between the wheel and axle housing
is made by a toothed clutch on the axle which fits into the toothed opening
on the hub of the wheel. This permits a certain amount of side play
and relieves the shaft from any stress or strain, if the axle housing should
become bent. If the connection between the rear wheel and axle is not
such that a certain amount of side action can be taken care of without
throwing a stress and strain on the shaft, it cannot be classified as a full-
floating axle. Axle shafts for both the full-floating and the fixed hub
types of rear axle are shown in Fig. 482. If an axle is of the fixed hub
type, it cannot possibly be full-floating.
291. The Differential. — The halves of the rear axle are connected at
the center through a gear mechanism called the differential. The use
of the differential is necessary in order that one rear wheel may turn faster
than the other when the car is turning a corner and when the outside rear
wheel must travel a greater distance than the inside one.
Each end of the axle shaft fits into a bevel gear, as indicated in Figs.
483 and 484. These gears, called differential gears, face each other and
mesh with smaller bevel gears carried on a spider and known as differ-
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REAR AXLES AND DIFFERENTIALS
397
ViijTir,!
BEVEL RMG
'IF. StfAFT
Fio. 483.— Differential gear.
AXLE
SHAFT
'D/FFEXENT/AL // D/FFEPENT/AL
GP ? — * // GEAP
D/FFEPENT/AL CASE
(R/GLLT)
TAPERED
'POLLEP
REAPING
m D/FFEPENT/AL
d/ff/pent/al sp/dep
PINIONS
D/FFEPENT/AL
rASF (/FED
AXLE Sh 'AFT
Fig. 484. — Parte of differential gear.
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398 THE GASOLINE AUTOMOBILE
ential pinions. The number of these differential pinions varies from two
to four, depending upon the design. The spider carrying the pinions
is held by the differential case which also keeps the differential gears in
mesh with the differential pinions. The differential case is attached to
the bevel ring or ring gear and revolves with it. The power goes from the
driving pinion to the bevel ring which causes the spider carrying the differ-
ential pinions to also revolve with it. The power is transmitted to the
axle shafts through the differential pinions and gears. With equal resist-
ance on each wheel, the differential pinions cause the differential gears
and, consequently, the axles, to revolve at the same speed. With the
same amount of power being delivered to each wheel there is no motion
of the teeth of the differential pinions over the teeth of the differential
gears.
When the car turns a corner, one rear wheel must obviously turn faster
than the other. Consequently, there will be a movement of the dif-
ferential pinions around their own axes and this action will cause one
half of the axle to turn ahead of the other, or one rear wheel to revolve
faster than the other wheel. Any movement of the differential pinions
on their own axes will accelerate the movement of one half of the axle
and retard the movement of the other half.
If the condition of the road or ground over which the car is being
driven is such that it is impossible for one of the rear wheels to get a
footing and it spins, it is then impossible to start the car as there will be
no traction for the other wheel. It will remain still, while all the power
will go toward spinning the one wheel. In some cases a special dif-
ferential lock for locking the differential has been installed. Special
differentials have been designed with the purpose in mind of preventing
stalling, due to a lack of traction on one wheel, but their application so
far has been limited.
Differentials using types of gearing different from the bevel gears
have been used in some cases. The spur gear differential employs spur
gears instead of bevel gears for obtaining the differential or compensating
action between the axle shafts. It is used very little at the present time.
The bevel gear differential is used almost universally.
292. M & S Differential or Powrlok. — As previously explained, the
main difficulty encountered with the bevel-gear type of differential is
that when one rear wheel slips or spins, due to a muddy or wet road sur-
face, the entire power of the engine goes to spinning this one wheel. This
means that there is no power delivered to the other wheel and, conse-
quently, the car cannot be started as long as the one wheel spins. This
difficulty has been avoided in the M & S Differential or Powrlok which is
shown in Fig3. 485 and 486.
The fundamental principle of this differential is the same as in the
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REAR AXLES AND DIFFERENTIALS
399
bevel-gear type. The construction, however, is somewhat different. In-
stead of using bevel gears, helical (commonly called spiral) gears with
45° angles are provided. The differential housing H carries the spider
P on which are mounted the four differential helical gears C. The
crown gears A and A l are fastened to the rear axle shafts which in turn
drive the two rear wheels. The differ-
ential housing also carries the worm
gears B which have their axes at right
angles to the axes of the differential
gears C. When the differential is as-
sembled the gears mesh as indicated
in Fig. 485.
When the road resistance on each
rear wheel is the same, the entire
differential revolves as a unit in ex-
actly the same way as the bevel-gear
differential. The helical gears have
no motion on each other and the
power is equally distributed to each
wheel. If one rear wheel should lose its traction on the road and start
to slip, there is no tendency for it to spin and take the entire power of
the engine because gears B are unable, on account of the angle of the
teeth, to drive gears A. Consequently, there is no differential action
and the axle turns as if solid, and delivers power to both rear wheels.
P. C
A^
B1-
^B
ffi>
iaB1
B'-
1
^-B'
c" "p
Fia. 485. — M and a differential.
Fig. 486. — Construction of M and S differential.
There is, therefore, no possibility of stalling the car as long as one wheel
has traction on the road.
When turning corners, the M & S Differential or Powrlok gives the
same differential action as a bevel-gear differential. This is made pos-
sible because gears A can drive gears B when one wheel has a tendency
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400 THE GASOLINE AUTOMOBILE
to move faster or slower than the other wheel. This differential action
takes place whether the car is going ahead or in the reversed direction.
293. Lubrication of Rear Axle and Differential. — It is very essential
that effective lubrication should be provided for the differential, axle, and
wheel bearings. These are lubricated by a semi-solid grease which is
carried in the differential housing. The differential and axle housings
are not usually oil-tight and a fluid oil cannot be used to advantage.
In addition, the semi-solid lubricant reduces the noise and prevents
excessive wear on the gear teeth. Lubrication through grease cups is
also provided for various parts of the axle. The differential should be
filled to the level of the filling hole every 2000 miles the car is run. The
wheel bearing at the axle ends should be thoroughly cleaned and repacked
with the proper lubricant every season and also every 2000 miles of
travel. In a great many cases an oil hole is provided on the wheel hub
Cfatch pedol
£nqfne
\ \ ^'Un/versaf tents \ Cfutch
Rear ox/e bousing ^Torston rods Transmission qeor rasa
Fig. 487. — Automobile power transmission system with torsion rods for taking the torque.
so that a little oil can be put in whenever the car is oiled. This oil
keeps the grease soft and in good workable condition.
294. The Torque Arm. — When the brakes are used in stopping the car,
the brakes, being carried by the rear axle housing, tend to carry this
housing around with the wheels. Likewise, the action of the propeller
shaft and the bevel or spiral pinion in driving the rear axles tend to turn
the axle housing over backward with the same force that is exerted
on the bevel ring. This tendency of the axle housing to turn over, due
to the action of the propeller shaft, is greater when the car is being started,
or when the car suddenly runs into sand or mud, where the resistance
to be overcome is greater. This twisting action or torque must be taken
care of in some way in order to prevent the axle housing from turning
over.
This torque can be taken by torsion rods, Fig. 487, running to the
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REAR AXLES AND DIFFERENTIALS
401
top and bottom of the rear axle housing, or by a single bar called a torque
arm. Figures 488 and 489 illustrates two typical types of torque arms.
With the use of a torque arm, it is possible to have the propeller shaft
run open without a housing, as the torque or twisting effect is taken
by the arm. If the propeller shaft is enclosed by a housing, and this
Fia. 488. — Torque arm on Packard Twin Six.
housing takes care of the torque, the housing is called a torque tube or
third member of the rear axle system. When a torque tube is used, it is
not necessary that a universal joint be used at the rear of the propeller
shaft. It should be understood that whenever the torque is taken by
a torque tube, by torsion rods, or a torque arm, that these members assist
Fiq. 489. — Westcott double tubular torque arm.
materially in driving the car, as one end is attached to the frame of the
car and the other to the rear axle.
It is the practice of a great many designers not to provide separate
means for taking care of the torque but to depend upon the rear springs
to do this as well as to drive the car. When this is done and the rear
26
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402
THE GASOLINE AUTOMOBILE
axle drives the car through- the rear springs, it is designated as the
"Hotchkiss Drive.' '
295. Strut Rods. — In order to assist in preserving the alignment
of the rear wheels, or to keep one wheel from getting ahead of the other,
strut rods are fastened to the brake flanges or spring seats and extend
Fig. 490. — Strut rods and torque tube on Marmon car.
to the front of the torque tube as in Fig. 490 or to some other part of the
car frame. In addition to keeping the wheels in alignment, the stmt
rods may also assist in taking up some of the torque action of the rear
axle.
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CHAPTER XIV
STEEL FELLOE^
WHEELS, RIMS, AND TIRES
The wheels, rims, and tires of an automobile are among its most
important parts. The rear wheels, in addition to supporting a large
part of the weight, transmit the power and drive the car. The front
wheels carry the weight of the front of the car and also serve to guide or
steer the car in the proper direction. The pneumatic tire, which is
universally used on automobile wheels, is responsible for most of the
present-day comfort and easy-riding
qualities of the modern passenger
cars. A great part of the expense in
operating a car is the money spent for
tires. If tires are purchased and used
with the proper care, the wear and mile-
age obtained from them can be a maxi-
mum and the expense can be reduced
to a minimum. On the other hand,
poor judgment in buying, and hard
treatment in use, may be responsible
for a great deal of unnecessary grief,
trouble, and expense on the part of
the car owner or driver.
296. Wheels. — The wheels of an
automobile are light but strong. They
must transmit the driving power from
the rear axle to the rear tires, and at
the same time resist the terrific side
strains caused by skidding and turning
corners rapidly.
The general arrangement of the
wheel, rim, and tire is shown in Fig. 491. The wheel proper may be
made of wood, of metal with wire spokes, or of light pressed steel. A
felloe which may be of wood or steel fits over the ends of the spokes
and holds them together.
The rim which carries the tire may be fixed 'permanently on the wheel
or it may be made removable, in which case the tire and rim are removed
together. After the tire and rim are removed from the wheel, the tire
403
SPOKE-
firFEREft
SPOKE
ENDS I
Flo. 491. — Arrangement of wheel,
rim, and tire.
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404
THE GASOLINE AUTOMOBILE
WOODEN
FELLOE
can be taken off the rim by prying one of the beads over the side of the
rim, if it is a solid one-piece rim. If the rim is built so that the tire
may be easily removed, due to some special constructional feature of
the rim, the name detachable is applied to the rim.
297. Wooden Wheels. — Automobile wheels made of wood are copied
after the wheels used on artillery buggies and are called artillery wheels.
The spokes are mitered and wedged together at the center as shown in
Fig. 492, and are held at the center by the flanges of the hub plates on
each side of the wheel. The hub plates are held together by bolts.
The holes for these bolts are in the spokes near the center of the wheel.
Second growth hickory is the best wood for wheels, but it is becoming
so scarce and expensive that the medium and lower-priced wheels are
sometimes made from oak or some other kind of wood.
The outside ends of the wooden spokes are held by a band called the
felloe. The felloe may be either a wooden band as in Fig. 492 or a steel
band, Fig. 491. The wooden felloe is
made by steaming and bending special
pieces of stock to the correct curvature
and fitting two such pieces together over
the spokes. A steel band is shrunk over
the wooden felloe to hold the assembled
parts together. Steel felloes are of
channel section and are usually made in
one piece.
With ordinary care, a well-made
artillery wheel usually causes no trouble.
The spokes may loosen and squeak dur-
ing a long spell of dry weather, especially
if the car is seldom washed. This con-
dition is aggravating not only to the oc-
cupants of the car: b|it is apt to cause distortion of the felloe and undue
wear of the tire. This should be attended to at once as wooden wheels
run with loose spokes have very short periods of usefulness. If the rim
used on the wheel is of the demountable type, the wedges which hold
the rim in place may also become loose and cause a squeaking noise.
They may become so worn that it will be impossible to tighten them
and new wedges will be required. In some cases the wheel itself is de-
formed as a result of loose wedges. If some of the wedges are tightened
more than others, the body of the wheel may be slightly deformed.
For this reason the wedges should be tightened uniformly.
When repair work is needed on wooden wheels, it should be put in the
hands of an expert. Only a person who is well acquainted with the
manufacture of wooden wheels can replace a broken spoke or take the
Fio. 492. — Wooden artillery
wheel with wooden felloe and de-
mountable rim.
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WHEELS, RIMS, AND TIRES
405
squeak out of the wheel without distorting it. When a good thorough
washing will not remove the squeak, it generally means that it has been
neglected too long.
298. Wire Wheels. — While the artillery type of wheel has been the
most commonly used, the wire wheel is gradually gaining favor for pas-
senger cars. Wire wheels are lighter and readily demountable, which
simplifies tire changing. The heat developed in the tire is conducted
from it to the hub of the wheel more readily in a wire wheel than in a
wooden wheel. This is true especially if the car speed and road friction
are such that the tire temperature is unusually high. The small diameter
of the spokes of a wire wheel give easier access to the brakes for the pur-
pose of adjustment. Some wire wheels have demountable rims 30 that
the wheels need not be removed for
changing tires. A wire wheel with
demountable rim is shown in Fig.
493.
One disadvantage of wire wheels
is that they are somewhat difficult
to keep clean. The spokes are also
easily injured when run in deep,
hard ruts and when they come in
contact with other objects. In re-
placing damaged spokes, the hub end
fits through the hub plate. The
other end is threaded and fits
through the felloe. The adjustment
is made by tightening the nut on
the threaded end. It is very im-
portant when replacing wire spokes that they be tightened the same
amount in order to prevent the rim from being pulled out of true.
The wire wheels are very easily applied and removed by means
of locking devices. The wheels are applied so that if the locking device
should fail the forward motion of the car would still tend to keep them on.
An automobile is run in reverse comparatively little, so for safety the
wheels are applied on the right side of the car with right-handed screws
and on the left side with left-handed screws.
One particular claim of the manufacturers of wire wheels is that they
are easier on the car and occupants, as more of the jolts are absorbed by
the wheel body. The wire wheels are built so that the weight of the car
is supported by the spokes above the hub in tension, while other types
of wheels support the load below the hub in compression. The compres-
sive support is direct from the road to the hub, while the stress in a
wire wheel is spread over the entire tire and rim to the upper spokes of
Fig.
493. — Wire wheel with demountable
rim.
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406
THE GASOLINE AUTOMOBILE
the wheel. Because of this, more of the shocks and jolts are absorbed
by the wire wheels, consequently are not transmitted to the car itself
and its occupants. This added resilience is another fact that assists
in giving greater tire mileage.
The two types of spoke lacing now in general use are shown in Fig. 494.
The relative strength of any two wire wheels cannot be determined en-
tirely from the number of spokes used. Much depends on the distri-
bution of the stress and the relative strength of the steel used in the
spokes of the different wheels.
Fig. 494. — Methods of spoke
lacing on wire wheels.
Fio. 495. — Section of pressed
steel wheel.
299. Other Types of Wheels. — In Europe, because of scarcity of
wood, a form of pressed steel wheel has become very popular. The hubs,
felloes, and spokes are stamped in halves. The halves are welded to-
gether so as to resemble the artillery form of wooden wheel. When
painted, a close inspection is needed to tell the difference. These wheels
are generally made demountable like wire wheels in order to make tire
changing easy. They can be made as cheaply as the wooden wheel and
much lighter.
Wheels of thin discs of pressed steel, as shown in Fig.* 495, are being
used on some of the higher-priced and heavier passenger cars. These
wheels are strong and durable and are also very easy to keep clean.
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WHEELS, RIMS, AND TIRES
407
Wheels made of cast steel are popular for trucks but it is difficult to manu-
facture them light enough for passenger cars.
300. Rims. — Rims for securing tires to the wheels of automobiles
may be divided into three types; clincher , quick detachable, and demount-
able. A combination of the quick detachable and demountable types is
also used extensively.
The Clincher One-piece Rim. — The clincher one-piece rim, Fig. 496,
is made in one piece with a pocket at each side for the clincher bead of the
tire. Such a rim can be made removable from
the wheel or can be fastened permanently to it as
in the case of the Ford rim and wheel. This type
of rim is considered the cheapest to manufacture
but it is difficult to remove the tire. It is made
practically the same for wooden and wire wheels.
Wire wheels, of course, have the advantage of Fio. 496.— Section of one-
being easily demountable. In the case of a punc- piece ° nc er nm*
ture or a blow-out, a wheel can be replaced by one with a tire already
inflated.
Figure 497 illustrates the method of removing a tire from a clincher
rim. The wheel should first be jacked up off the road or floor. After
removing the valve cap and lock nut, the valve stem should be pushed
in until it is flu3h with the rim, and the shoe or bead of the tire then loos-
Seoond Position
of Tiro Tool
Run Tool
Around Edge
of Rim
Fiq. 497. — Method of removing tire from clincher rim.
ened by working the tire with the hands. A tire tool should be inserted
under the bead as shown in the first position. Great care must be taken
to see that the inner tube is not pinched by the tire tool. A second tire
tool should then be inserted and used to work the bead over the rim as in
position three. Either one or both tools may be used in doing the work
shown in position four. The casing should then be moved so that the
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408
THE GASOLINE AUTOMOBILE
inner bead is nearer the outside edge of the rim. The inner tube may
now be removed without pinching at any point. In removing the inner
tube the start should be made diametrically opposite the position of the
valve stem, and finally the stem itself lifted from its hole in the felloe.
\CJbm/
\ rh
Demountabk rim
Ft/lo€
roggk ""*
Fe/lot band
Dtmountabk rim
Gamp
%hmpino fa/r
Fia. 498. — Demountable clincher rim.
The clincher rim may also be made demountable, as illustrated in
Fig. 498. After the rim and tire are removed from the wheel, the method
of getting the tire off the rim is the same as with the clincher rim which
is fixed on the wheel.
Quick Detachable or Q. D. Rims. — A quick detachable rim is con-
structed with a removable ring on one side, Fig. 499, so that the tire can
Fio. 499. — Quick detachable rim with
removable ring.
Fio. 500. — Inserting tool to remove
ring on quick detachable rim.
be removed from it very easily. This outside retaining ring is split
and a place provided for inserting a tool so that one end may be pried
up as in Fig. 500. The entire ring is then removed, and the deflated tire
taken off.
Quick detachable rims are manufactured in three types; the quick
detachable clincher, the quick detachable straight sidef and the quick de-
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WHEELS, RIMS, AND TIRES
409
tachable universal. The quick detachable clincher is a combination
clincher and detachable rim, as shown in Fig. 501. This is an uncommon
type of rim. It is usually demountable as well as detachable, in which
case it is called the Q. D. demountable clincher rim.
The quick detachable straight side rim differs from the clincher rim
in that the sides of the rim are made straight to fit the straight side type
Fiq. 501. — Quick detachable clincher
rim which is also demountable.
Fiq. 502. — Detachable straight side
rim also demountable.
of tire, as in Fig. 502. The demountable and detachable features are the
same as for a clincher rim. Figure 503 illustrates a detachable straight
side rim which is not demountable.
The side rings of the universal type of rim are made reversible as in
Fig. 504 so that a tire of either the clincher or of the straight side type may
Fiq. 503. — Detachable straight side
rim which is not demountable.
Fiq. 504. — Quick detachable
universal rim.
be used. In addition to being detachable, these rims are usually made
demountable.
Demountable Rims. — A rim is demountable when provision is made for
removing the rim, together with the tire, from the wheel easily and quickly.
This feature is very desirable as it permits a quick change of tires in case
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410 THE GASOLINE AUTOMOBILE
of a puncture or a blow-out. A fully inflated tire may be carried on an
extra rim which can be placed on the wheel in case of emergency.
Demountable rims are held on the wheel either by a special locking
device as in Fig. 498, or by wedges placed around the circumference of
the wheel. The locking device in Fig. 498 locks the rim on the wheel
at a single point. When the toggle nut of the locking device is in its
lowest position, the clamping ring is drawn down into the groove and the
rim is released. By screwing the toggle nut up, the rim becomes locked
on the wheel. Various forms of wedges are illustrated in Figs. 501 and
502. These wedges or clamps may be held either by a nut fitting over
a stud or by a bolt extending entirely through the rim.
The demountable rims are either of the one-piece clincher or of the
detachable type. All types of quick detachable rims may be made
demountable. They would then be called Q. D. demountable rims. The
Fio. 505. — Split-band type of demountable rim.
split-band type of demountable rim, as shown in Fig. 505, is also used.
The rim may be removed from the tire, by unlocking the ends.
301. Removal of Demountable Rims. — When it is necessary to re-
move a tire,. all the clamps or wedges under the demountable rim, except
the two nearest the valve stem, are loosened with the brace as shown in
Fig. 506. This should be done before jacking up the wheel. (The weight
of the car holds the wheel steady for this work.) The wedges are turned
out of the way and should be fastened. The wheel should be raised from
the ground with the jack and the tire tool inserted between the rim and
the felloe on the side of the wheel opposite the valve stem, as shown in
Fig. 507. The rim can be pried off the wheel at this point. By having
the valve stem at the lowest point, the rim can be slipped off the wheel
without lifting it. Just the reverse is done when the rim and tire are
put on the wheel.
The operations for removing a split-band type of rim from the tire
are shown in Fig. 508. The rim and tire are put flat on the ground and
the anchor plate which holds the two ends of the rim together is removed.
The long side of the end containing the valve stem should be up. (The
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WHEELS, RIMS, AND TIRES 411
cut in the rim is slanting.) One end of a tire tool is inserted near the
cut under the bead of the tire at that end of the rim which does not con-
tain the valve stem. The other end is forced downward and toward the
center of the rim. This forces the end of the rim out of the tire. The
tire tool is then removed and inserted about 6 in. farther from the cut,
on the same side, and the operation repeated. The tire and the rim
must now be turned completely over. The free end of the rim may be
taken hold of with both hands, and by holding the tire flat on the ground
with one foot, the rim may be pulled out entirely. In putting the tire
back on the rim the operation is reversed, in which case care must be
taken that both beads of the tire are properly seated in the rim. The tire
tool may be used if the beads are too stiff to work by hand. The end of
Fig. 606. — Loosening wedges before re- Fio. 507. — Inserting tool for removal
moving demountable rim. of demountable rim.
the rim should not be slipped into place until the rest of it is properly
placed.
Care of Rims. — All rims should be inspected frequently to see if they
are rusting. If rust has started, it should be removed carefully with
a sharp tool, the spot smoothed with emery, and rim paint used. This is
very necessary in order to save the tires.
302. Types of Tires. — Automobile tires may be divided into two kinds:
pneumatic and solid or cushion. Pneumatic tires are universally used for
passenger carrying cars. They may be divided into three types from the
standpoint of construction: fabric, cord, and fabric cord. They may also
be classified according to the type of rims for which intended, as, clincher,
quick detachable clincher, and straight side, as shown in Fig. 509. The
regular clincher tire differs from the Q. D. clincher in only one respect.
The beads of the regular clincher type are filled with rubber composition
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and are very flexible so as to be easy to remove. The Q. D. clincher beads
have a core of many turns of piano wire surrounded by the same compo-
sition, which gives a stronger and stiffer bead than that of the regular
clincher type. Straight side tires have the beads constructed in a simi-
Fiq. 508. — Operations in the removal ofjgplifc-band type of rim from tire.
lar manner. As the names signify, each of these tires fits into a rim of
its own particular type, and should never be placed in any other kind of a
rim. Straight side tires are believed to be more durable and stronger and
are recommended as a standard by the Society of Automotive Engineers
for all sizes larger than 30 in:
Quick detachable
clincher.
Regular
clincher.
Fiq. 509. — Types of tires.
Straight side.
303. Construction of Tires. — Figures 510 and 511 illustrate the con-
struction of fabric tires. Several layers of heavy canvas (friction fabric)
are wound around two circular braids of piano wire (beads) into the shape
of a tire. A thin layer of rubber gum is placed between all layers of the
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WHEELS, RIMS, AND TIRES
413
fabric. The canvas used in the construction of these tires is prepared by
forcing rubber composition into the meshes of the cloth. Five or six
TREAD
BREAKER STRIPS
RUBBER TREAD OR
WEARING SURFACE
LAYERS OF FABRIC
FORMING CARCASS
OF TIRE
Pra. 510. — Construction of J. and D. fabric tire.
f Tread
.Breaker
Cushion
7th Ply
©tti Ply
5-th Ply
■4+ii Ply
3rd Ply
pEnd Ply
Mst Ply
Fiq. 511. — Construction of Quaker City fabric tire.
layers of this fabric wound in this manner form the carcass around which
the cushion is built. This cushion is an extra thickness of compounded
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rubber held in place by a double layer of canvas which is called the breaker
strip. Outside of this is the tread which comes in contact with the road
and, consequently, takes the wear. There is also a thin layer of rubber
over the sides. This whole structure is then vulcanized or baked into a
solid unit. Great care and considerable experience are needed in this
operation as too much vulcanizing will make the rubber hard and brittle,
while too little vulcanizing will leave it too soft to resist wear.
The fabric is laid with the threads on a bias of 45°. This is done
so that in case of rupture the break will not run the entire circumference
of the tire. The layers of thread running one way bend on the layers
running the other, causing the fabric to wear and the threads to break.
This is one disadvantage of fabric tires.
In cord tires, layers of cord instead of fabric are wound on the tire
on a bias of 45° as shown in Fig. 512. On account of the fact that the
cords in any one layer are parallel to each other there is no bending of
Fiq. 512. — Internal construction of cord tires.
one over the other as in the case of the threads on the fabric tire. Adja-
cent layers of cord are laid with the cords at an angle of 90° to each other.
There are usually two to five layers of cord, depending upon the size of
the cord. Otherwise, construction is the same as of fabric tires. There
is less internal heat generated because there is not the continual rubbing
of the threads upon one another. A stiffer carcass is the result of this
cord construction. The better riding qualities of cord tires are due chiefly
to this fact as the tires will carry the given load with less air pressure and,
consequently, with more resilience. The air pressure in a cord tire
should be about 10 per cent, less than the air pressure in a fabric tire of
the same size, carrying the same load. This is due to the increased
resiliency of cord tires. A car fitted with cord tires will invariably coast
farther down a hill than the same car fitted with fabric tires. Cord
tires give the best possible service with moderate upkeep cost and
economy of power.
Fabric cord tires are constructed of about the same number of layers
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WHEELS, RIMS, AND TIRES 415
as fabric tires. Heavy cords are used in one direction, while threads are
used at right angles to the cords. These threads are woven in with the
cords and hold them together as in a piece of fabric. In the layers of
fabric cord there is not the tendency to wrinkle that there is in the layers
of fabric. The strain is carried better in each layer of fabric cord by the
heavy cords running in only one direction than in tires of fabric construc-
tion. In other respects, the construction is similar to cord tires.
Cord tires and fabric cord tires are much harder to repair than fabrie
tires, and the first cost is greater.
The side walls in all pneumatic tires must be thin and elastic as the
greatest strains occur there. If the side walls were as heavily reinforced
as the tread, the constant stretching would cause the fabric to break and
the rubber to crack, the cushioning effect of the tire would be impaired
and the car would ride much harder.
Inner tubes are simply air-tight bags of compounded rubber with
mechanical one-way air valves. They are very carefully made and if
properly used should give long wear and service.
304. Proper Use and Care of Tires. — One of the most important prob-
lems in the care and operation of an automobile is that of giving the
proper care and attention to the tires. This is important because tires
are one of the chief items of expense. The cost per mile for tires alone can
be reduced considerably with just a little extra attention and care on the
part of the owner. Tire troubles come mainly through neglect and can
be avoided in most cases. Some of the things which should be given
special attention are:
1. Proper inflation of tires. 13. Oil on tires.
2. Tires of proper size. 14. Light and heat on tires.
3. Care in application of tires to 15. Fast driving.
rims. 16. Poorly made repairs.
4. Rim irregularities. 17. Tire powder.
5. Flat tires. 18. Inserting inner tubes.
6. Fabric bruises. 19. Care of spare tubes.
7. Improper braking. 20. Leaky air valves.
8. Tight chains. 21. Tire fillers.
9. Wear of tire by parts of car. 22. Tire protectors.
10. Alignment of wheels. 23. Spare casings.
11. Ruts and car tracks. 24. Care of tires — car in stor-
12. Neglected injuries. age.
305. Proper Inflation. — No exact rule can be given for the proper
inflation of tires as the strength of tires of the same size, as made by dif-
ferent manufacturers, will vary considerably. The best rule to follow
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is to use the pressure recommended by the manufacturer of the tire.
This pressure has been determined by test and experience. It will
average about 20 lb. per inch of cross-section of the tire for the rear
tires with possibly a slightly lower pressure for the front tires. The
front wheels generally support less weight and can of tenbe run at lower
pressure.
It is impossible to guess at the correct pressure in a tire. A pressure
gauge should always be used as it will indicate the correct pressure.
These gauges are simple, are not expensive, and save many times their
cost.
Over one-half of the failure of tires to give the proper mileage is
due to under-inflation. It is not generally known in this connection
that over 60 per cent, of the total loss of
power between the engine and the road is
consumed by the tires in internal friction,
and that under-inflation of the tires may
cause as high as 25 per cent, increase in the
Piq. 513. — Condition of tire when under-
inflated.
Fio. 514. — Breaking down of side
walla due to under-inflation.
power necessary to drive a car. It is, therefore, advisable to keep the
tires properly inflated to save gasoline as well as to save the tires.
The inflation pressure should be practically the same in summer as in
winter. The heat from the road, together with the greater heat gen-
erated in an under-inflated tire, destroys the casing much more rapidly
than if the tire were properly inflated. The increased pressure in a tire
due to hot weather is negligible as compared with the inflation pressure.
The excessive strain on the side walls of a casing, due to the bending
when it is under-inflated, causes heat to be generated and the layers of
fabric to try to slide over one another. Eventually, this strain causes a
separation or breaking of the binding between the layers of fabric and
rapid deterioration of the tire. A break in the fabric may result from
crossing tracks or hitting a stone when a tire is under-inflated because
of the excessive strain, A blow-out may possibly follow. The distor-
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WHEELS, RIMS, AND TIRES
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tion of an under-inflated tire is shown in Fig. 513 and the consequent
breaking down of the side walls in Fig. 514. The result of under-inflation
on the outside of the casing is illustrated in Fig. 515. The tires should
always be inflated to the proper pressure and this should never be per-
mitted to decrease more than 20 per cent.
306. Tires of •Proper Size* — Overloading tires has exactly the same
effect as under-inflation. The table below gives the maximum allowable
load for the different sizes of tires.
Site of tires
Load per wheel in
pounds
Sise of tires
Load per wheel in
pounds
2J4 in. all diara.
225
30 X 4 in.
550
3 in. all diam.
350
32 X 4 in.
650
28 X 3H in.
400
34 X 4 in.
700
30 X 3M in.
450
36 X 4 in.
750
32 X SH in.
550
32 X 4^ in.
800
34 X ZM in.
600
34 X 4^ in.
900
36 X 3^ in.
65fy
36 X 4H in.
1000
j-
All 5 in.
1000 or over
Most cars are fitted with regular size tires at the factory so that the
tires may be replaced with their over-sizes, when necessary. Even when
cars are not overloaded at any time many owners prefer to use over-size
tires on account of their greater strength, the lessened vibration, and
greater tire mileage. A comparison of the regular with its over-size
to fit the same rim is shown in Fig. 516. The following table gives
the common sizes in regular tires and their corresponding over-size:
Regular sise tire
Over-sise tire
30 X 3
31 X SH
30 XSH
31 X 4
32 XSH
33 X4
32 X 4
33 X4K
34 X 4
35 X4%
34 X4H
35 X 5
36 X«
37 X 5
36 X 5
37 X5H
If it is thought that over-size tires are needed, this may be determined
by the use of large platform scales. (The ground surrounding the scales
should be level and even with them.) The car should be placed so that
the front wheels rest on the platform. The middle of the car should be
over the edge of the scales. With the car in this position and fully
loaded the reading of the scales should be taken. This weight divided
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by two gives the weight supported by each tire. The car should now
be driven across the scales and a reading taken for the rear wheels in the
same manner.
307. Care in Application of Tires to Rims. — Tires of the clincher
type cannot be fitted to straight side rims nor can straight side tires
be fitted to clincher or Q. D. clincher rims. If uni-
versal rims are used care should be taken that the side
rings are properly placed for the type Qf tire being
used.
308. Rim Irregularities. — Dented, irregular, and
rusted rims are commonly the causes of cutting the
beads of tires. If irregularities are not removed from
the rims, new tires will wear very quickly and have very
short lives. All rust should be carefully removed with
emery cloth, and some preservative like rim paint used.
309. Flat Tires. — When a tire goes flat overnight
(or shortly after being properly inflated) it is almost
always due to a loose or leaky air valve. In this case
the tube should be removed and the nut at the base
of the valve stem tightened or the valve cap removed
and reversed so as to tighten the valve itself. It may
be found that an entirely new valve is needed. In the
Fio. 515. — Result of
u rider-inflation.
Fig. 516. — Regular and over-size tires on same rim.
case of a puncture, the tire will generally go flat while the car is run-
ning. An experienced driver will immediately notice the difficulty in
steering. The car should not be run on a flat tire. It should be
stopped and temporary or permanent repairs made before the tire is
completely ruined. Rim cutting and broken side walls result from
running on flat tires.
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810, Fabric Bruises. — Tire bruises are, perhaps, harder to avoid than
any other tire troubles. While it is impossible to avoid every rock or
obstruction in the road, it is possible to avoid backing into curbs and fast
driving over tracks, which are very common causes of fabric bruises.
Many drivers also run the front wheels against a curb, when the brakes
are not working properly, and do not try to dodge deep holes in the
pavement.
A break in the fabric can be noticed on the inside of the casing shown
in Fig. 517. It was caused by a severe blow received by the tire. The
Fiq. 617. — Broken fabric.
fabric of a tire may give way under such a blow although no permanent
mark may be left on the outside. This does not indicate that the tire
was defective in any way, but usually indicates carelessness on the part
of the driver. Such a bruise may be given to the tire weeks before the
blow-out occurs. The blow-out may happen while the car is left standing
at the curb or in the garage. Such a fabric bruise has even been known to
pinch the inner tube so as to cause a slow leak.
311. Improper Braking. — No one would expect to use a sharp file on
one spot of a tire for any length of time without doing it permanent in-
jury, and yet this practically happens when the brakes are used to keep
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THE GASOLINE AUTOMOBILE
the wheels from turning before the car stops. The wheels of a moving
car should never be stopped suddenly with the brakes while the car is in
motion, except in case of great danger. The roadbed makes an excellent
file, and the pressure between the road and the tire makes the filing action
exceedingly severe. Figure 518 shows the effect on a tire caused by lock-
mg the wheels with the brakes and of sliding the tire over the pavement
or road. It is inexcusable for any
other cause than an emergency and
is a very expensive practice.
312. Tight Chains.— Anti-skid
devices of all kinds are severe on
tires. Chains should always be
put on a car so that they are loose
Fiq. 518. — Scraped tire due to
improper use of brakes.
Fia. 519. — Tire injured by chains.
enough to creep around the tire and not wear the same spots. They should
not be so loose as to be noisy. Any anti-skid device that is fastened to
the spokes should not be used. Figure 519 shows the result of using tight
chains on a tire. In this case the chains could not shift around the tire
and, consequently, the wear came on the same spot. Mudhooks may be
used in getting a car out of very muddy holes and out of deep snow.
They should be removed as soon as possible. Under no condition should
chains or any other similar device be used any longer than is absolutely
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421
f
necessary. They must be used occasionally, but they are extremely
hard on tires.
313. Wear of Tire by Parts of Car. — Care should be taken to see that
no projections from the car touch the tires; that the fenders are not bent
so as to wear on the tires; that the car is not so over-
loaded that any part of the car will scrape the tires; and
also that the springs or spring clips are not broken.
These things cause unnecessary wear on the tires and
unnecessary expense. There should be enough clear-
ance between the bumpers and the tires to prevent rub-
bing. This rubbing is more liable to occur when over-
size tires are used- Sharp turns may cause tires to
come into contact with or to rub against some spring
shackle or bolt. Rapid wear of tires is sometimes caused
in this manner.
314. Alignment of Wheels. — A large part of front
wheel tire trouble is due to faulty alignment of the
wheels. (This may be caused by a bent axle, steerjng
rod, or knuckle; or by loose or crooked demountable
rims.) If the front wheels are out of alignment the tires
will undergo a grinding action as they pass over the road.
This action is very destructive to the treads and should
not be permitted to continue. Figure 520 shows the re-
sult of this filing action of the roadbed caused by wheels
being out of alignment. Rear wheels, as a rule, do not
get out of alignment as frequently as the front ones.
The alignment of the wheels can be checked by measur-
ing the distances between the felloes of the wheels in
front of the axle and then behind the axle. All measure-
ments should be taken at the same height from the
ground, preferably at the same height as the axle. The
measurement in front of the front axle should not exceed
the measurement behind the front axle by more than %
to % in. There should be no difference in the measure-
ments at the rear wheels.
315. Ruts and Car Tracks. — The result of driving
a car in ruts is shown in Fig. 521. The side walls are
purposely made the thinnest part of the tire and yet many drivers often
drive in ruts because it is a trifle easier than to keep out of them. The
fabric soon becomes worn and weakened from wear, and dampness may
get to the fabric and rot it. The result is the same when the sides of a
tire are scraped against curbstones. Running in car tracks causes a
similar condition nearer the tread.
Fig. 520. —
The result of
poor wheel align-
ment.
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THE GASOLINE AUTOMOBILE
316. Neglected Injuries. — It is expensive to repair neglected cuts and
oftentimes they cannot be repaired at all. A little attention given to the
tires each day will save much tire expense. Tacks, nails, and glass may
be easily removed if attended to daily, and the holes may be plugged
before they enlarge and moisture penetrates to the fabric. In the case
of a large cut, rubber may be applied and a small vulcanizer used to do the
repair work. Fewer tire cuts will result if a driver will always slightly
accelerate the car so as to coast over loose
crushed stone and similar surfaces.
When cuts are neglected the elasticity of
the rubber allows them to expand under the
weight of the car; sand, mjid, and water are
forced into them and they keep growing larger.
Moisture gets to the fabric causing it to de-
teriorate rapidly. With each revolution more
foreign matter accumulates which finally causes
a mud-boil. Either a complete separation
from the tread or a blow-out is the result.
317. Oil on Tires. — Quite often a car is
left standing in puddles of oil in a garage.
This should never be done as oil softens the
rubber causing it to wear just as though it
had been improperly cured. Most of the
damage from oil is probably due to grease
working from the brake drums to the side
walls of the tires. This should be looked for
as it can be easily removed by a cloth damp-
ened with gasoline before damage results. Oil
may cause a separation between the layers of
fabric and at the same time damage the fabric
itself.
318. Light and Heat — Extra casings
should be protected from the light by being
well wrapped and spare casings should be kept
in a dark, cool, dry place whenever possible, or the tires will not give the
expected mileage. Rubber bands, as commonly used in office work, be-
come old and so brittle that they will break if used. Tires also slowly
deteriorate whether they are used or not. Both light and heat make
this deterioration more rapid.
319, Fast Driving. — During a 600-mile race on a speedway, a car may
use from 8 to 10 of the best obtainable casings any one of which could
ordinarily be used in running 6000 miles. The filing action of the road
on tires is very destructive when speeding. Each time a wheel leaves the
Fio. 521. — Rut-worn tire.
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ground and comes to earth again, there is this filing action. In turning
corners at a high rate of speed the strain on the side walls is excessive,
and is very apt to cause trouble. When driving 20 to 25 miles per hour
little trouble should be experienced. When a car is driven at a greater
speed the tires will give less mileage.
320. Poorly Made Repairs. — The pressure in a tire is so great that all
repairs must be well made in order to be effective. This is especially
true of repairs for blow-outs. Figure 522 shows a tire that blew out due
to defective repairs. Originally, it had a small cut clear through the cas-
ing. The inside patch was not applied properly and did more harm than
Fio. 522. — Blow-out from ineffective repairs.
good. As shown in the figure, the pressure forced the patch through the
hole, wedging the fabric apart, and causing it to break from bead to bead.
The inside view shows the patch pulled away from its original position
and forced through the break. This condition is the result of defective
repairing. An inside protection patch, used with an outside emergency
band, should be used until permanent repairs can be made to take the
strain at the weakened point.
321. Tire Powder. — When an inner tube is inserted in a casing it
should be perfectly dry, and the casing prepared by dusting lightly with
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424 THE GASOLINE AUTOMOBILE
powdered soapstone, sometimes called French chalk, or talcum, or with
powdered mica. This serves as a lubricant and keeps the tube from
sticking to the casing or from chafing. Too much powder should not
be used as it may collect in lumps and the resulting pressure and chafing
damage the inner tube.
322. Inserting Inner Tubes. — When an inner tube is inserted in the
casing it should not be allowed to wrinkle. It should be slightly inflated
and care taken to see that it does not get pinched under the beads or by
an inner shoe if one is used. The flaps should be properly placed, the
one containing the larger hole on top, and care taken to see that they do
not slip around the casing as this causes chafing of the inner wall and
often results in worn fabric.
After a tire is punctured, the inside of the casing should be examined
before the repaired tube or a new one is put in. If a tack or piece of
glass is visible on the inside of the casing it should be removed. Road-
side repairs of the casing, due to such injuries, are not usually necessary,
Fiq. 523. — Proper method of folding inner tube.
but the cut should be repaired as soon as possible. A spare tube should
be inserted if there is one and the damaged one repaired later by vul-
canizing. If the damaged one must be used, a vulcanized repair is
preferable. It may be repaired temporarily with a patch. The patch
should be removed later for a vulcanized repair, as tubes patched with
cement seldom last as long.
323. Care of Spare Tubes. — Spare tubes deteriorate the same as
casings. Much can be done to lengthen the life of spare inner tubes
by keeping them properly folded in an oil-proof, dust-proof, and light--
proof bag when not in use. They are easily injured and heavy articles
should#not be placed near them or thrown on them. A little care given
to them will save much trouble and expense.
In rolling a spare tube, the valve should be removed and all the air
forced out. The valve should then be replaced so that no more air can
enter. The valve stem should be covered with a piece of chamois skin
or cloth. The tube should be laid out flat with the valve stem up as
shown in Fig. 523. Each end should be folded over so that it almost meets
the other at the valve stem. The tube should then be folded at the
valve stem with the stem on the inside of the fold. The roll should be
fastened or tied rather loosely with broad tape so as not to injure the
tube. It should then be placed in a bag.
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WHEELS, RIMS, AND TIRES 425
324. Leaky Air Valves. — Leaky air valves may be easily discovered
the same as punctures. Bubbles rising from the valves when the tube,
slightly inflated, is immersed in water, indicate that the air valve is
leaking. This is a common source of tire trouble and may be repaired
in some cases by simply tightening the valve or the nut at the base of
the valve stem. An entire new valve stem or a new valve maybe
necessary.
326. Tire Fillers. — A common question is "Do tire fillers mend cuts
and keep the tires in good condition?" They may mend cuts but their
use cannot be recommended. The opinions of two leading manufac-
turers of tires in regard to tire fillers follow:
1. Avoid the use of any substitute for air. Our guarantee is with-
drawn when substitutes are used.
2. Tire manufacturers waive the guarantee and responsibility for
tires when a substitute for air is used. Car manufacturers discourage
excess weight on wheels.
Tire fillers which fill the tires completely are added weights which
reduce the resiliency. No filler can be as resilient as air. A puncture
cure or filler that does not fill a tire completely is an unbalanced weight
that will distort the tire in time and tend to shorten its life rather than
preserve it. Besides, puncture cures do not mend cuts from the outside
and a permanent injury may be done to the casing before the inside is
punctured at all.
326. Tire Protectors. — Reliners, inside protectors, and tread attach-
ments add extra weight, cause additional heat by friction between sur-
faces, and interfere with the radiation of such heat. If reliners are made
of flexible material and are well constructed, they are good things to
use in old casings. They protect the inner tubes and make it possible to
secure much greater mileage from them. Reliners should never be used
in new tires as they tend to flatten them just as they are flattened by
under-inflation.
327. Spare Casings. — Spare casings should never be carried so that
oil or water can collect in the supports. If they are tied or strapped
tightly with anything narrow the jolting of the car will cause the straps
to cut the tire through natural wear. As mentioned before, they should
be protected from light and heat as much as possible.
328. Care of Tires — Car in Storage. — Casings and tubes should be
removed from the rims when a car is in storage and placed in a cool, dark,
dry place. If the car is out of use temporarily, it should be jacked up
so that no weight rests on the tires. If the car is not to be used for some
time, even though it is not put away for an entire season, it is best to
remove the tires and examine the rims for rust. The casings and tubes
should also be protected from dust and dirt.
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426 THE GASOLINE AUTOMOBILE
329. Repair of Tires. — Tire repairs, except for minor cuts and punc-
tures, should usually be made by an expert tire repairman. A car owner
or driver should, however, become familiar with the processes and
operations that are used in repairing and vulcanizing casings and tubes.
Every large tire company publishes a complete booklet on repairing
and vulcanizing tires which if studied carefully will give all the necessary
information on these subjects. A small vulcanizer for home use is better
than one for roadside repairs. Roadside repairs can seldom be made as
they should be.
Important Points about Tires —
1. Keep tires inflated to the proper pressure.
2. Never rim the car on a flat tire.
3. Do not jam on the brakes so as to keep the wheels from turning.
4. Avoid skidding.
5. Keep out of ruts and car tracks, and do not scrape sides of tires
against curbs.
6. Avoid sharp obstructions. Do not run tires against curbs. Go
over bumps and car tracks slowly.
7. Apply chains in proper Way but do not use them for a time longer
than necessary.
8. Keep the front wheels in proper alignment.
9. Repair small cuts promptly.
10. Insert inner tubes with care. Do not use too much talc or lubri-
cant.
11. Keep tires free from oil and grease.
12. Keep rims free from irregularities and rust.
13. Carry spare casing and tube in bag.
14. Never use substitutes for air.
15. Buy good tires and give them the best possible care.
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CHAPTER XV
AUTOMOBILE TROUBLES AND REMEDIES
330. Classification of Troubles. — The manufacturers of automobiles
are constantly striving to simplify the design and construction of all parts
in order to reduce the number of troubles which are a constant source of
worry to the automobile owner and driver. They have been quite
successful in reducing troubles to a minimum; as a matter of fact, the
possible troubles on the modern car are now few in number compared with
those of not a great many years ago. The troubles now commonly
experienced are those inherent in every man-made machine which is
subject to the wear and tear of everyday use.
It is obviously impossible, in many cases, to give a direct statement of
a cure for all of the various symptoms which are likely at some time or
other to confront the motorist, as some symptoms may be due to one or
more of several different causes. All that can be done is to offer a few
general suggestions which will assist him to diagnose his own specific
troubles and apply the proper remedy.
The automobile is a fine piece of machinery and the service from it
will depend upon the care and attention given to it. Many of the
troubles on the modern automobile are due to uncalled for adjustments
and investigations by the motorist. Although good care and attention
must be given in order to get efficient service, it is good policy to leave
well enough alone and not do any unnecessary tampering, nor try to
improve upon the operation or construction as planned by the
manufacturer.
The more common motor-car troubles may be divided into the follow-
ing general headings:
i . ii in
Power plant troubles Transmission troubles Chassis troubles
* (a) Mechanical parts of engine (a) Clutch (a) Wheel hubs
(6) Carburetting and gasoline (6) Change gears (6) Steering gear
system
(c) Ignition (c) Differential (c) Brakes
(d) Lubricating and cooling (d) Rear axle (d) Springs
(e) Starting and lighting (e) Tires
331. Power Plant Troubles. — Any derangement in the power plant
will show itself by one of the following symptoms. Under each symptom
427
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428 THE GASOLINE AUTOMOBILE
is given the common causes with a reference to the discussion on the
subject.
1. Engine Jails to start
(a) Poor compression. See Art. 332a.
(6) Engine cylinder flooded. See Art. 333e.
(c) Carburetor adjustment not right. See Art. 333.
(d) Water in gasoline. See Art. 333?.
(e) Dirt in gasoline. See Art. 333k
(/) Carburetor frozen. See Art. 333?.
(g) Carburetor throttle lever disconnected.
(h) Out of gasoline,
(t) Engine too cold. See Art, 333/.
(j) Ignition switch off.
(k) Foul or broken plugs. See Art. 3346.
(I) Weak batteries or magneto. See Art. 334&, I, and m.
(m) Loose or corroded battery terminal. See Art. 334J.
(n) Vibrators not properly adjusted. See Art. 334#.
(o) Wiring system out of order. See Art. 334c.
(p) Ignition not timed properly. See Art. 334,;.
(q) Cylinders not wired in proper order of firing,
(r) Defective condenser. See Art. 334e.
(s) Resistance unit burned out. See Art. 334/.
2. Engine misses at low speeds
(a) Poor compression. See Art. 332 a.
(6) Mixture too lean or too rich. See Art. 333a and 6.
(c) Carburetor not suitable for the kind of fuel used.
(d) Spark plug gap too wide. See Art. 3346.
(c) Spark plug cable not connected or short-circuited. See Art. 334c
CO Dirty interrupter. See Art. 334d and m.
(g) Dirty or defective spark plug. See Art. 3346.
(h) Vibrator not properly adjusted. See Art. 334#.
(t) Weak magneto magnets. See Art. 334m.
3. Engine misses at high speeds
(a) Carburetor not set for this speed. See Art. 333.
(6) Bad spark plug. See Art. 3346.
(c) Spark plug gap too wide. See Art. 3346.
(d) Weak valve spring. See Art. 332c.
(c) Timer or breaker contact imperfect. See Art. 334t.
(/) Interrupter contacts adjusted to open too far. See Art. 334d and m.
(g) Vibrator points dirty or burned. See Art. 334j?.
(h) Defective condenser. See Art. 334c.
(t) Ignition timed too late. See Art. Z34j.
(j) Weak interrupter spring.
4. Engine misses at all speeds
(a) Carburetor not properly adjusted. See Art. 333.
(6) Carburetor not suitable for kind of fuel used.
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AUTOMOBILE TROUBLES AND REMEDIES 429
(c) Dirty or broken plug. See Art. 3346.
(d) Spark plug gap not right. See Art. 3346.
(«) Poor compression. See Art. 332a.
if) Bent or worn valve stem. See Art. 332c and d.
(g) Leak in intake manifold.
(h) Valve tappets adjusted too close. See Art. 332c.
(i) Broken piston rings or scored cylinder. See Art. 332c.
(j) Valves not timed properly. See Art. 332d.
(k) Loose or broken terminals. See Art. 334c.
(0 Weak batteries or magneto. See Art. 334/:, /, and m.
(m) Defective wiring. See Art. 334c.
(n) Coil not properly adjusted. See Art. 334p.
(o) Interrupter not adjusted to proper opening. See Art. 334d and m.
(p) Defective condenser. See Art. 334c.
(q) Weak interrupter spring,
(r) Wrong type of ignition coil used.
(«) Ignition improperly timed. See Art. 33^;.
(t) Cracked distributor head. See Art. 334c.
(u) Safety gap too small.
(v) Gasoline feed stopped up. See Art. 333A.
(w) Needle valve bent or stuck,
(x) Water in gasoline,
(y) Poor water circulation. See Art. 3376.
(z) Excessive lubrication. See Art. 337a.
5. Engine overheat*
(a) Lack of proper water circulation. See Art. 3376.
(6) Lack of proper lubrication. See Art. 337a.
(c) Slipping fan belt or bent fan blades. See Art. 3376.
(d) Too rich a mixture. See Art. 333a.
(c) A weak mixture. See Art. 3336.
(J) Running with spark retarded. See Art. 334;.
(?) Ignition timed too late. See Art. 334.;.
{h) Carbon deposit in cylinders. See Art. 332/.
(t) Broken water pump. See Art. 3376.
(/) Water too low in radiator. See Art. 3376.
(k) Radiator too small.
(0 Frozen radiator. See Art. 3376.
(m) Brakes dragging. See Art. 339c.
(n) Choked muffler.
0. Engine stops
(a) Gasoline tank empty.
(6) Water in gasoline. See Art. 333?.
(c) Sediment in gasoline. See Art. 333/i.
(d) Carburetor flooded. See Art. 333d.
(e) Lack of pressure on gasoline tank. See Art. 333i.
(/) Carburetor throttle control rod disconnected.
(g) Overheating due to poor circulation or lack of lubrication. See Art. 337.
(h) Excessive lubrication. See Art. 337a.
(t) Short-circuiting of wires or terminals. See Art. 334c.
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430 THE GASOLINE AUTOMOBILE
(j) Disconnected or broken wires. See Art. 334c and h.
(k) Defective condenser. See Art. 334e.
(0 Wet batteries or magneto. See Art. 334A;.
7. Engine knocks
(a) Carbon deposits in cylinder and on piston heads. See Art. 332/.
(6) Spark too far advanced. See Art. 334j.
(c) Running motor slow when pulling heavy load on direct drive.
(d) Faulty, lubrication. See Art. 337a.
(e) Engine overheated. See Art. 331-5.
if) Loose connecting-rod bearings. Sec Art. 332y.
(g) Loose piston. See Art. 332e.
(h) Loose flywheel.
(t) Loose crankshaft bearings. See Art 332y.
(j) Valves not timed properly. See Art. 332d.
(k) Compression too high. See Art. 332a.
(I) Operating on wrong kind of fuel for carburetor,
(m) Improper spark-plug installation. See Art. 146.
8. Engine trill not stop
(a) Short-circuit in switoh.
(6) Magneto ground may be disconnected.
(c) Overheating and carbon deposits. See Art. 332/.
9. Lack of power
(a) Poor compression. See Art. 332a.
(6) Too weak or too rich a mixture. See Art. 333a and b.
(c) Operating in high altitudes.
(d) Weak spark. See Art. 334c.
(e) Ignition timed too late. See Art. 334?.
(/) Running with spark retarded. See Art. 334j.
(g) Valves not timed properly. See Art. 332d.
(h) Valve tappets not adjusted properly. See Art. 332c.
(i) Valves not seating properly. See Art. 3326.
(J) Lack of lubrication. See Art. 337a.
(k) Lack of cooling water. See Art. 3376.
(/) Lack of gasoline.
(m) Dragging brakes. See Art. 339c.
(n) Slipping clutch. See Art. 338a.
(o) Plat tires,
(p) Choked muffler causing back pressures.
10. Back-firing through carburetor
(a) Improper needle valve adjustment. See Art. 3336.
(6) Dirt in gasoline passage or nozzle. See Art. 333A.
(c) Inlet valve not closing properly. See Art. 332d
(d) Excessive temperature of the hot-water jacket of the carburetor, especially
in hot weather. This can be remedied by shutting off the water from the
carburetor jacket and cutting off the hot air supply.
(c) Spark retarded too far. See Art/ 334j.
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AUTOMOBILE TROUBLES AND REMEDIES
431
11. Firing in muffler
(a) Weak mixture, slow burning exhaust, igniting unburned charge from
previous miss. See Art. 3336.
(b) Exhaust valves not closing properly. See Art. 332d.
(c) Valves out of time. See Art. 333d.
(d) Too rich a gasoline mixture. See Art. 333a.
(e) Occasional misfiring of a cylinder. See Art. 334a.
12. Starter will not operate
See starting troubles, Art. 335.
332. Mechanical Troubles in Engine, (a) Poor Compression. —
* Poor compression is one of the common causes for lack of power. Unless
HIGH TENSION CABLE
Insulation worn off,
cable not attached
SPARK PLUG
Broken, fouled, hose,
gap too wide ***n^
VALVE CAP^.
^ Loose
'ATER SPACE
Pitted with sediment
PRIMING COCK
I Loose
VALVE SEAT-^^
Pitted, scored. *"-
covered with carbon
MANIFOLD JOINTS.
Not tight
VALVE STEM _
Bent, stuck
VALVE SPRING
Too weak broken,
out ofpfoce
CLEARANCE—
To much or too little I M VALVE
THROTTLE VALVE
Disconnected from
throttle valve rod
GASOL/NE FLOAT^
Soaked or logged
FLOAT VALVE'"
Stem bent seat
leaks, va/ve stuck v l AUXILIARY
on seat lA/R VALVE .
GASOLINE NEE0LE
VALVE / -
Bent or stutk ■
CAM'' J
Contour worn /
TIMING GEARS'''
Gears not meshed
properly
VSTON RINGS
Loose, broken,
misplaced
PISTON
Worn, too loose,
out of round
- WRIST PIN
Worn, loose
CYLINDER WALLS
Scored, worn
^DISTRIBUTOR
Dtrty
TIMER LEVER
INTERRUPTER
OR TIMER
Contact potnts not
property adjusted
— CRANK PIN
Worn, out of
round
-CONNECTING ROD
BEARING
Loose, worn
^CRANK SHAFT
Bearings worn
Fig. 524. — Chart showing location of common mechanical troubles of engines.
the compression pressure is high enough, the explosion will be lacking
in force and the engine will be weak. The engine can be turned by hand,
with the ignition off, throttle open, and the compression noted in each
cylinder, or a more accurate way is to remove the spark plug and screw in
a small pressure gauge, which should show from 60 to 80 lb. at the end of
the compression stroke, depending on the make of engine. Loss of corn-
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432
THE GASOLINE AUTOMOBILE
pression is commonly due to leaky or improperly seated valves, or to leaky
joints. Leaky thread joints, valve caps, or cracks in cylinder are com-
mon causes for loss of compression. These can be detected by a hissing
sound or, if the suspected leak is covered with gasoline or oil, the leak
will show itself by a bubbling through the oil. If the trouble cannot
be located in this manner, attention should be given to the valves.
As a rule, the intake valve requires less attention than the exhaust
valve, because the former comes into contact "with the cool, fresh fuel
charges, whereas the latter is apt to become fouled and burnt by the hot
and dirty exhaust gases. A frequent cause of leaky valves is carbon
deposit on the valve seats. These deposits prevent the proper seating
of the valves. The remedy is to clean and grind them.
(6) Grinding Valves. — There are several good grinding compounds
on the market. It is advisable to use a coarse grade in the first operation
and then to finish off with a finer one
to give a polished surface. A very
good homemade mixture is obtained by
making a thin paste of a couple of
?** ,, tablespoouf uls of kerosene, a few drops
| of oil, and enough fine emery flour to
thicken to the consistency of paste.
The valve spring must be removed
so that the valve may be lifted and
turned. A moderate coating of the
paste is applied to the bevel face of the
valve. The valve is next rotated back
and forth until the entire bearing sur-
face is polished bright and smooth the
full width of the face. The valve should never be turned the whole
way round but rotated back and forth not over a quarter turn under
light pressure. It should be lifted frequently and turned halfway round
before being replaced on the seat again. This method distributes the
friction evenly and eliminates the possibility of the emery scoring the
valve seat. If no valve grinding tool is available, the use of a car-
penter's brace or bitstock is recommended, as a much smoother move-
ment is thus obtained than by using a screwdriver. The use of this
method, recommended by the Overland Company, is shown in Fig. 525.
After grinding to a good clean seat entirely free from spots or pits,
wash the valve, valve seat, and guide thoroughly in gasoline. If the
stem is rough or gummy, smooth it up with emery cloth, but clean it
afterward before replacing it in the guide. To test the effectiveness of
your work, mark the valve seat in several places with a lead pencil
Fig. 525. — Valve grinding.
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AUTOMOBILE TROUBLES AND REMEDIES
433
and turn the valve around a few times. If the marks are entirely rubbed
off, the work may be considered well done.
(c) Valve Adjustment. — Poor adjustments of the valve operating mech-
anism may cause poor compression, even if the valve seats have been
properly ground in. The valve spring may be broken or too weak to close
the valve on its seat in the proper time. Sticking of the valves when open
may also be the cause of low compression.
The clearance between the valve stem and push rod may be the cause
of considerable trouble. This clearance is usually about the thickness of
Voire Spring -
Spring Dm
Adjusting Sere-
Gun Shaft
Fig. 526. — Adjustment of push rod clearance.
a thin visiting card, the exact amount being somewhat different for dif-
ferent cars, but never over 3^2 *n-
If this clearance for the intake valve is too great, the lift is reduced,
thus preventing the proper charge from getting into the cylinder. If
the exhaust valve lift is reduced in the same way, it will be more difficult
for the exhaust gases to escape. Too much clearance also changes the
28
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434
THE GASOLINE AUTOMOBILE
time of valve opening and closing, causing the valves to open late and
close early. If, on the other hand, this clearance is too small or entirely-
absent, the valve will open early and close late, or will not close on its
seat at all.
As the valve seats are lowered by continual grinding, the clearance
is gradually changed. For the proper operation of the valves, careful
attention should be given to this clearance space. Figure 526 illustrates
the clearance adjustment on the Overland car.
A weak spring on the exhaust valve may have a marked effect on the
operation of the engine. The exhaust valve will then open on the suc-
tion stroke and burnt gases will again be drawn into the cylinder.
(d) Valve Timing. — It is essential that the valves be properly timed
or set, in order to have the engine operate properly. The valves are
set at the factory and the necessity for
adjusting the timing comes as the re-
sult of wear on the valve seats, stems,
rods, cams, half-time gears, or by im-
proper replacement of any of these
parts. If the camshaft has been re-
moved, care must be taken to mesh
the gears properly when replacing it.
The gears are marked so that replace-
ment is not difficult- The proper
method of replacing the gears on the
Ford engine is shown in Fig. 527. It
will be noticed that there is a prick
punch mark on one tooth of the pinion
and a corresponding mark on the large
gear. Before taking a camshaft out,
Fig. 527. — Ford camshaft setting, an examination should be made and if
showing marked tooth and space on the gears are not so marked it should
be done before they are disturbed.
If the clearances are properly adjusted for the push rods and valve
stems and if the timing gears are properly meshed, the valves should be
correctly timed, making allowance for wear on the cam faces. On most
engines the positions at which the valves start to open and close are
marked on the circumference of the flywheel. These points should be
opposite the pointer, usually at the top of the case, when the valves
start to open. and close. This time can be determined by the use of a
thin sheet of tissue paper. By placing a piece of the paper in the clear-
ance space between the push rod and valve stem, one can tell when the
valve opens or closes.
Valve setting is an adjustment that should be made by an experienced
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AUTOMOBILE TROUBLES AND REMEDIES
435
mechanic or one thoroughly familiar with the principles of the four-
stroke engine. The different makers have found by trial the settings
that will give the best result with their engines and cars. These settings
differ somewhat according to different conditions. If they are not
marked on the flywheel, they should be obtained from the manufacturer.
Figure 528 shows the approximate crank and piston positions for the
valve events. The inlet may open anywhere from top center to 20°
of flywheel motion after center. The inlet closes from 25° to 50° past
lower center. The exhaust opens 35° to 60° before lower center and
closes from top center to 15° past center.
(e) Loose Piston or Scored Cylinder Walls. — A loose piston or scored
cylinder walls will cause a marked loss of compression. If the piston is
not too loose, slightly larger rings may be put on. Sometimes the
Inlet closes. Exhaust opens.
Fig. 528. — Valve setting diagram.
Exhaust closes.
blowing can be remedied by using a heavier cylinder oil. This will, to
some extent, remedy the trouble caused by scored cylinder walls,
although if too badly cut, they must be rebored and new pistons and rings
fitted in. Again, this is the work of an experienced mechanic.
(/) Carbon Deposits in Cylinder. — After the engine has been run for
some time, carbon deposits are liable to collect in the cylinder and on the
pistons, especially if too much lubricating oil or gasoline has been used.
The carbon deposit resulting from too much lubricating oil is a sticky
substance, while that from too much gasoline is hard, dry, and brittle.
These deposits, if allowed to collect, become hot from the heat of
explosion, and may cause preignition of the fresh charge of gas.
The best methods of removing carbon deposit are to scrape it out
or to burn it out by means of an oxygen flame. The latter method is
quicker and by far the more convenient. For an engine with a non-
detachable cylinder head the following method is recommended by the
Overland Company for the removal of carbon by scraping:
To scrape the cylinders, remove both inlet and exhaust valve caps,
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436
THE GASOLINE AUTOMOBILE
Fig. 529, and turn the motor over until the pistons of two cylinders are
at their top centers. The scraping off of the deposit is done by means of
tools of different shapes, the tools being bent so as to reach the piston
head and the sides and tops of the cylinders. Scrape all loose carbon
over to the exhaust valve and when through, turn the motor until the
exhaust valve lifts when the carbon may be scraped past the valve and
into the exhaust passage, whence it will be blown out. To do a good
job, brush the surface clean and make sure that no carbon becomes
lodged between the exhaust valve and its seat. Finally wash with
kerosene.
In replacing the cylinder plugs over the valves, put graphite grease
around the threads; this will make a compression-tight joint and also
make it easier to remove the plugs the
next time. Likewise, be sure to replace
the copper gaskets under the plugs.
It is an excellent plan to remove the
carbon and to grind in the valves at the
same time.
Kerosene may also be used for the re-
moval of carbon from the cylinders. Two
or three tablespoonf uls should be poured
through the priming cocks while the
engine is warm. The kerosene has a
strong solvent action on any gummy
binding material in the carbon. The
kerosene can be spread over the entire
cylinder by cranking the engine a few
times around. Some motorists inject the
kerosene through the air valve of the car-
buretor just before the engine is stopped,
preparatory to putting the car away. Kerosene will not remove a hard
carbon deposit but it will prevent it from forming if used regularly,
about once a week.
Running the engine on alcohol for a few minutes is another device
that is sometimes used for burning out carbon deposits.
(g) Bearing Troubles. — The common bearing troubles are those caused
by the bearings becoming worn and loose, with a consequent knocking.
Faulty lubrication, clogged oil pipes and oil holes, and dirty oil are the
main causes of warm or hot bearings. The bearings which are most
liable to give trouble are the wrist pin bearings, the connecting-rod bear-
ings, and che main crank bearings. After a bearing has been excessively
hot, it should be refitted by a mechanic. A loose bearing can be tightened
on the pin by removing the liners or shims, or by refitting it.
Fig. 529. — Scraping the cylinders.
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AUTOMOBILE TROUBLES AND REMEDIES 437
333. Carburetion Troubles. — Improper mixture is the common source
of carburetor troubles. An improper mixture is either too rich, that is,
too much gasoline in proportion to the air, or too weak, that is, too much
air in proportion to the gasoline.
(a) Mixture too Rich. — A rich mixture can be detected by black
smoke coming from the muffler, and by overheating and missing of the
engine. Not only is fuel wasted, but the cylinders become fouled and
carbonized. A mixture which is too rich at slow speeds can be corrected
by cutting down on the gasoline, and at high speeds by increasing the
auxiliary air. An auxiliary air spring which sticks, a restricted air opening,
or a flooded carburetor will cause an over-rich mixture.
(b) Mixture too Weak. — A weak mixture can be detected by back-
firing through the carburetor and by occasional muffler explosions. A
weak mixture, being a slow-burning mixture, is still burning when the
intake valve opens for the following charge. This permits the flame to
shoot back through the manifold ihto the carburetor. A weak mixture
gjiould not be confused with an improperly timed intake valve which
opens before the burning charge has been exhausted. If the intake
valve has a weak spring, which does not close the valve properly, it may
permit back-firing through the carburetor. The back-firing caused
through valve trouble is usually more violent than back-firing due to a
weak mixture. A weak mixture at low speeds is caused generally by
too little gasoline and at high speeds by too much auxiliary air. The
carburetor should be adjusted accordingly.
Air leaks in the manifold connections will dilute the mixture with
air and cause a weak mixture and back-firing. These leaks should be
closed before the carburetor adjustments are made.
A stuck or bent or obstructed gasoline needle valve may cause a weak
mixture by shutting off the supply of gasoline. The remedy is obvious.
(c) Color of Explosive Flame. — By opening the priming cocks on the
cylinders, the color of explosive flame can be seen as it issues from the
cocks. A blue flame indicates a perfect mixture, a red flame indicates
an excess of gasoline, and a white flame indicates an excess of air.
(d) Flooded Carburetor. — If the carburetor float becomes gasoline
soaked or filled with gasoline, it will not shut off the gasoline float valve
and the carburetor float chamber will become filled with gasoline. The
remedy is to take the float out and if it is made of cork, have it dried out,
painted with shellac, and baked. If of the hollow metal type it should
be emptied and the hole soldered. A small particle of dirt under the
float valve will also cause the carburetor to become flooded.
(e) Flooded Cylinder. — If the engine has been cranked for some little
time and too much gasoline has been sucked into the cylinders, the cylin-
ders become flooded with almost pure gasoline which condenses in the
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438 THE GASOLINE AUTOMOBILE
cold cylinders. This charge will not explode. The remedy is to open
the priming cocks and crank the engine until the over-rich mixture has
been expelled or diluted. After the priming cocks are closed, the engine
can usually be started. Flooding of the engine may also be caused by
priming the cylinders with too much gasoline. It sometimes happens
that a flooded engine can be started without difficulty after standing for
several hours, the excess gasoline having evaporated in the meantime.
(/) Cold Weather Starting. — In cold weather, when the engine is
stiff and the gasoline is hard to evaporate, it is desirable to inject a little
warm or high test gasoline into each cylinder through the priming cocks.
The carburetor may also be heated by the application of warm cloths.
The priming gasoline can be heated to advantage by placing a bottle of
it in a pan of Jiot water.
(g) Frozen Carburetor. — If there is water in the gasoline this water
may be frozen in the carburetor. The water, being heavier than the
gasoline, sinks to the bottom where it may freeze in cold weather. To
remedy this trouble apply hot cloths to the parts affected. Never use a
torch or flame of any sort around the carburetor.
(h) Feed System Stopped Up. — If, after priming, the engine starts
and suddenly dies down, the gasoline supply may be exhausted, the feed
pipe may be clogged, or a piece of dirt may have worked into the needle
valve.- If there is a supply of gasoline and the trouble is found to be due
to dirt in the feed system, the feed pipe may be disconnected and the dirt
blown out. A particle of dirt in the needle valve may be removed by
screwing the valve shut and then opening it the proper amount. This
trouble and also the one due to water in the gasoline can be prevented by
straining the gasoline through a chamois skin before putting it into the
main tank.
(i) Loss of Pressure on Gasoline Tank. — It sometimes happens that
if a pressure gasoline system is used, the pressure becomes too low to
force the gasoline from the main tank to the auxiliary tank. This causes
a lack of fuel at the carburetor. A hand pump is usually furnished for
increasing this air pressure on the tank.
If the car is equipped with a gravity feed system, the gasoline may
fail to run to the carburetor when ascending a steep hill. It sometimes
becomes necessary to back the car uphill, in which case the gasoline will
run to the carburetor without difficulty.
(j) Water Logged Carburetor. — It sometimes happens that the car-
buretor becomes loaded with water, due to the fact that the water can
neither evaporate nor get out. This water prevents the gasoline from
getting in. The water should be drained from the carburetor drain cock.
334. Ignition Troubles. — Misfiring or " missing" of the engine may be
caused from faulty ignition, a faulty carburetor, or from the valves operat-
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AUTOMOBILE TROUBLES AND REMEDIES 439
ing improperly. Missing which occurs with some regularity may usually
be attributed to faulty ignition or valve operation. Very irregular
missing is usually caused by faulty carburetor, but may result from dirty
breaker points or some other fault in the ignition system.
(a) Locating a Misfiring Cylinder. — To detect and correct faulty igni-
tion, the cylinder at fault must first be located. This may easily be
done with the engine running by short-circuiting the spark plug or bridg-
ing between the engine cylinder and spark-plug terminal with either a
hammer head or a screwdriver which has a wooden handle as shown in
Fig. 530. If, in testing the various spark plugs, one is found which, when
short-circuited, does not affect the operation of the engine, it is in all
probability the one at fault. The
trouble may be either in the ignition
apparatus or in the spark plug itself.
Another convenient method of
locating a misfiring cylinder on engines
having vibrating coil ignition, such
as the Ford, is to run the engine first
on one cylinder then another by hold-
ing down all of the vibrators except
the one connected to the cylinder
under test. The engine should run
idle on any one of the cylinders and
should show approximately the same *»■ ^-^ZVL^*** a ^
power from each.
(b) Defective Spark Plugs. — The most common fault found in the
spark plug is carbonizing or sooting, which results in short-circuiting
the high-tension current so that, instead of jumping between the points
or electrodes of the plugs in the combustion chamber, it passes through
the carbon accumulation directly to the metallic shell. The plug should
be removed, and if there is evidence that it is short-circuited the carbon
accumulation should be removed. This may be done by first scraping
off the carbon and then washing the plug with gasoline and a stiff brush.
Inspect the plug carefully to determine whether or not the porcelain has
become cracked or damaged in any way. Next determine if the gap or
distance between the electrodes is correct. This gap should be between
.025 to .030 i}/±§ to y$2 in)> about 3 thicknesses of an ordinary U. S.
post card. If this gap is found incorrect, the electrode that is attached
to the shell may be bent until proper adjustment is secured. A worn
dime is a good gauge to use for setting this gap.
The porcelain of the plug may be cracked in such a manner that it
will not show upon casual inspection, but it may be detected as follows:
If the plug is screwed into the cylinder and some pressure is brought to
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440 THE GASOLINE AUTOMOBILE
bear against the upper part of the plug with the finger, grating or grind-
ing will sometimes be heard and a very small motion will be felt. The
high-tension current will often bridge the gap between the center elec-
trode and the shell through a crack in the porcelain, instead of jumping
across the space intervening between the electrodes or points of the plug.
The spark plug may be tested by removing it from the cylinder and laying
it upon the cylinder block. The engine should be turned over by hand
and observations made as to whether a spark jumps between the elec-
trodes. The plug should, of course, be laid on the cylinder block so
that no part of the plug, save the shell, will touch the cylinder block.
This, however, is not a positive test, as the spark may sometimes jump
the gap between the points of the plug and yet be at fault, owing to the
fact that under compression the resistance is greatly increased between
the plug electrodes. The spark may jump this gap in the open air and
yet not pass under the conditions of operation in the cylinder.
A positive test for the plug is to replace it with one that is known to
be perfect. If the condition of operation is improved the original plug
is unquestionably at fault.
(c) Defective Wiring and Ignition Apparatus. — If the plugs are found in
good order, and yet one or more cylinders continue to misfire, the trouble
may be due to a lack of secondary current in the wire connected to the
plug. The trouble can be located when the engine is running, or being
cranked, by detaching the wire from the plug and holding the end about
% to 34 m- irom the plug binding terminal or cylinder head. If the
secondary current is being distributed properly to the cylinder in question,
a spark will occur at the gap. If there is no spark across the gap and
there is regular sparking at the other plugs, the trouble is undoubtedly
due to defective high-tension wiring, cracked distributor head, or poor
timer contact.
If the rubber covering or insulation on the spark-plug .wires is chafed
or cut through, allowing the conductor to touch or nearly touch any
metal part of the car, the current will be short-circuited and will not jump
the gap in the plugs. It is not necessary that this insulation be worn
down to the metal of the conductor. If a sharp snapping is heard when
the engine is running under a heavy pull it is evidence of a short-circuit
from the high-tension conductor to the frame. The fault will usually
be found due to imperfect insulation of the spark-plug wires, or a wire
loose from the spark-plug terminal. The only satisfactory remedy for
cracked insulation is to replace the wiring with new.
Irregular misfiring of all cylinders may be due to defective primary
wiring, discharged battery, weak magneto, corroded or loose battery
connections, improper adjustment of vibrator or interrupter contact
points, or defective condenser.
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AUTOMOBILE TROUBLES AND REMEDIES 441
(d) Battery Ignition Breaker. — A common cause of irregular misfiring,
when ignition is from a battery high-tension distributor unit, is improper
make-and-break of the primary circuit by the contact points. In a
majority of the various systems employed, the contact points are made
of tungsten and normally held closed by spring tension, the spark occur-
ring the instant the primary circuit is broken by the cam lobe bearing
against the contact arm. The contact points have a standard opening
of .17 to .020 in., about the thickness of two U. S. postcards. If found
dirty or uneven and pitted, they should be cleaned by passing a fine flat
file, or preferably a piece of No. 00 sandpaper, between them.
(e) Defective Condenser. — A defective condenser is indicated by seri-
ous sparking and rapid burning of the interrupter or vibrator contact
points, also by the inability of the coil to produce a hot secondary spark
when the primary circuit is interrupted. If these conditions exist,
the condenser is probably either punctured (insulation between tinfoil
layers destroyed) or open-circuited. The best remedy is to replace the
condenser, or unit in which it is contained, with another that is known to
be good. If the condenser is mounted inside the coil, the entire coil
usually must be replaced. However, when the condenser is mounted in
the breaker housing it can usually be replaced without disturbing the
other parts of the system. The action of a good condenser results in
intensifying the secondary current nearly 25 times and preventing an
arc at the breaker points when they are separated.
(J) The Resistance Unit. — In many battery ignition systems, a re-
sistance unit is placed in the primary circuit to protect the coil and bat-
tery in case the ignition switch is left on, and to aid in equalizing the
intensity of the secondary spark at high and low engine speeds. In
case the resistance unit should burn out, or, for any other reason become
open-circuited, the primary circuit is opened and no current can be ob-
tained at any of the plugs. This resistance unit consists of a small coil
of iron wire and is usually placed either on the coil or on the breaker
housing. In case this resistance unit should be burned out or accidentally
broken, the terminals may be temporarily short-circuited with a piece of
wire to relieve an emergency, but in all such coxes the resistance unit must
be replaced with another of the same kind as soon as possible. Continued
operation without it will result in serious burning of the interrupter
points and may cause injury to the coil and condenser.
(g) Coil Adjustments. — A frequent cause of no current at the plug
is due to coil trouble, especially where a vibrating coil is used for each
cylinder. When the vibrator points become pitted, out of line, or burned,
good contact is impossible. The tension on the vibrator spring may also
become changed, permitting the coil to consume too much or too little
current.
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442 THE GASOLINE AUTOMOBILE
In the case of burned or pitted points, they should be either filed flat
with a thin smooth file, or preferably a piece of No. 00 sandpaper passed
between them. In either case the points should be shaped so as to meet
each other squarely.
If it becomes necessary to adjust the tension on the vibrators, the
tension should be entirely taken off and gradually increased until the
engine runs satisfactorily under all load conditions with the coil consum-
ing as little current as possible. It is very important to have all the
units adjusted alike. This can be easily done after a little experience.
The most accurate method of coil adjustment is with a coil current indi-
cator by which the amount of current consumed is measured. Coils
are built to consume about % to 1)4 amp.; consequently, the tension
should be adjusted so that the current consumption of each coil is not
much greater than this amount.
(A) Breakdown of Coil Wiring or Insulation. — If no current is ob-
tained in the secondary circuit of a coil when the vibrator is working as it
should, the trouble is probably due to either a broken wire or punctured
insulation inside of the coil. It sometimes happens that the binding
post wires become loose from the post just inside of the coil. If only a
slight spark can be obtained, the insulation on the inside wire may be
broken down, thus causing a short-circuit of the current. Obviously,
there is no remedy but to replace the coil. Moisture in the coil may also
cause it to become short-circuited. In this event the coil should be
thoroughly dried out before it is put back into service.
(i) Timers. — Trouble in the timer is usually due to oil, water, or dirt
which has gotten into the housing, causing either a short-circuit or poor
contact. This foreign matter should be cleaned out of the timer in order
to permit it to give good service. After a time, the contact segments in
the timer become worn and irregular, causing misfiring at high speed.
In this event, it will be necessary to supply a new timer.
(j) Improper Spark Timing. — If the engine kicks back after cranking,
the spark is too far advanced and should be retarded so that it will not
occur until the piston has passed the dead center. The tendency of an
early spark on starting is to cause the engine to start backward. Too
early a spark at low speeds will make the engine knock and will cause the
car to jerk.
A retarded spark causes the engine to overheat and lose considerable
of its power. There is no advantage in retarding the spark past center,
even in starting. When the engine is running, the spark should be ad-
vanced in proportion to the speed. With the spark control lever fully
retarded, the interrupter points should be timed to open (thus causing the
spark) when the respective pistons are on upper dead center at the end
of their compression strokes.
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AUTOMOBILE TROUBLES AND REMEDIES 443
On cars equipped with automatic spark advance, the troubles due
to early and late spark are seldom experienced, providing the original
timing of the spark was correctly made. Preignition from other causes,
however, may occur with either type of spark advance.
(A:) Dry Batteries. — Weak or exhausted batteries are a common source
of trouble. If the batteries are suspected, they should be tested with a
small ammeter. If any one of the dry cells shows less than 6 amp., it
should be taken out and replaced with a new one. One weak cell will
interfere greatly with the operation of the others in the set. Occasionally,
a weak dry cell can be livened up temporarily by boring a small hole
through the top and pouring in a small quantity of water, or better still,
vinegar. The effect, however, is only temporary.
A dry battery should always be kept perfectly dry. If it becomes
wet on the outside, there is a tendency for the battery to be short-cir-
cuited and exhaust itself. This is true especially if water is spilled on
the top of the battery between the terminals.
(I) Storage Batteries. — If the storage battery appears dead, or shows
lack of energy, it may be due to one of the following causes: (a) dis-
charged; (b) electrolyte in the jars too low; (c) specific gravity of
electrolyte too low; (d) plates sulphated; (e) corroded terminals; (/)
battery terminal broken loose from the plates; or (g) broken down
insulation. These troubles are fully treated in the chapter on Storage
Batteries.
If the same battery is used for starting and also for ignition and the
battery has very little charge, the battery may not be strong enough to
produce a spark at the same time that the starting motor is drawing
current to turn the engine over. In this case the engine will generally
start if cranked by hand.
(m) Magneto Troubles. — If the ignition trouble has been located in
the magneto side of the ignition system and the plugs and wiring system
have been found in good working order, attention should be turned to the
magneto itself. The distributor plate should be thoroughly cleaned with
a cloth moistened with gasoline, to rerfiove any foreign matter such as oil
and carbon dust which may have collected. It should then be deter-
mined whether or not the magneto is generating current. To make this
test, first disconnect the magneto grounding, then, with either the spark-
plug cables disconnected from the plugs or with the distributor block
removed, rest, a screwdriver on the magneto frame, holding the point of it
from \& to y± in. from either the collector ring or slipring brush terminal,
and watch for the spark to jump this gap. If no spark appears the
trouble is in the magneto itself.
The contact points may be pitted or burned or may not have the
proper adjustment. The correct opening of the magneto interrupter
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444 THE GASOLINE AUTOMOBILE
points is from .012 to .020 (approx. ^4) in. If they are set too close,
excessive arcing will occur and the points will burn, and cause weak
spark at high speeds. If set too wide, the result will be burning of the
points and weak or no spark at high engine speeds, in which case
the primary winding does not have time to "build up," thus decreasing
the strength of the spark. If the interrupter points are found dirty or
badly pitted and uneven, they may be cleaned by passing a thin flat file
or a piece of No. 00 sandpaper between them.
The contacts should not be filed unless absolutely necessary.
The carbon or collector brushes may be dirty or worn. They should
be'cleaned, or if badly worn, replaced with new brushes, making sure that
each brush has the proper spring tension.
It occasionally happens that the magnets become weak or demag-
netized or they may be placed on the magneto in the wrong position.
If weak or demagnetized, they should be remagnetized before being
replaced. Care should be exercised in getting the like poles of the
magnets on the same side of the magneto. Most magnets are marked
with an N, indicating the North pole.
(n) Premature Ignition. — Premature ignition or preignition is caused
by particles of carbon, sharp corners, etc., becoming incandescent from
the heat of explosion and igniting the charge on the compression stroke
before the spark occurs. Preignition occurs generally when the engine
is laboring under a heavy load at slow speed such as when going up a
steep hill on high gear. Any engine will have premature ignition if it
becomes excessively hot under low speed and heavy load, but the tend-
ency to preignite is much more marked if the cylinder is full of carbon
deposits. These carbon deposits should be cleaned out as explained
before. Preignition may also be due to improper spark-plug installation
such as using a plug which extends too far into the cylinder head and
which is not properly cooled.
336. Starting Troubles. — If the starting motor fails to start at all
when the starting switch or pedal is pressed down as far as it will go, the
trouble may be tested out as follows:
(a) With a low reading voltmeter connected across the battery ter-
minals, note the voltage reading while the starting switch is closed tem-
porarily. If the voltmeter indicates less than 4% volts (for a 6-volt
battery) the electrical supply is defective. This in turn may be due to:
(a-1) Battery nm down or battery solution low. The remedy is to
fill the cells with distilled water to the proper level, and recharge.
(a-2) Battery defective. This is possible if the battery has been
operated for considerable periods in a nearly discharged condition or
with plates exposed above the solution. The only remedy is to repair
the battery.
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AUTOMOBILE TROUBLES AND REMEDIES 445
(a-3) Loose, rusty, or corroded connections at the battery terminals
or battery ground connections. To prevent corrosion, clean the terminals
thoroughly with either ammonia or soda solution and cover the parts
with a light coating of vaseline or cup grease.
(o-4) Heavy short-circuit in the starting circuit. This may be due to
heavy short circuit in starting motor field or armature winding, or acci-
dental ground at the brush connectors or motor or starting switch
terminals.
(6) If voltmeter indicates more than 4% volts as in (a) :
(6-1) The starting switch pedal connections and adjustments should
be examined to see that they have not worked loose in such a way that
the switch will not close. This can be readily checked, when the starting
switch is pushed down, by temporarily bridging across the switch ter-
minals with a pair of pliers or a heavy copper wire. If, then, the motor
does not start or attempt to start, the fault is not in the switch.
(6-2) A broken wire or loose connection should then be looked for in
the circuit from battery to starting switch; from switch to starting motor;
from motor to ground; and from battery to ground.
(6-3) Next, the brushes and commutator should be examined to see
that they are in good condition, not sticky with oil, and that the brushes
are making contact with the commutator with the proper spring tension.
If the commutator is black and pitted it should be cleaned by holding
a piece of No. 00 sandpaper (do not use emery cloth) next to the com-
mutator segments when the armature is rotated by hand. Any dirt
or oil found on the commutator or brushes should be cleaned off by using
a lintless cloth moistened with gasoline.
(c) If, in the flywheel type starter with Bendix drive, the motor
spins but does not crank the engine, the pinion may fit too tight on its
shaft, the threads may be clogged, the pinion shift spring may be broken,
or there may be some teeth broken off in the flywheel gear. In the case
of motor-generators, the trouble may be in a broken chain, broken driving
gear, or a slipping over-running clutch.
If the motor rotates until the pinion meshes with the flywheel and
then stops rotating, the engine or some of its auxiliary parts may not
be moving freely due to: improper lubrication, binding of the bearings
and pistons, etc., or the battery may be discharged or of too small a
capacity for the engine.
(d) If the starting motor continues to run after the starting switch
pedal is released, the starting switch spring should be examined to see
if it has proper tension to return the parts positively and fully to the
"open" position.
336. Lighting Troubles. — When trouble arises in the lighting system
it should be located and corrected at once to prevent possible damage to
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446 THE GASOLINE AUTOMOBILE
other parts of the electric system. The reason for this is, not that a
burned out Jamp in itself will be injurious to the system, but because oft-
times the real trouble causing the lamp to burn out is in the battery or
generating system, which, if neglected, may prove more disastrous than
the mere burning out of the lamp. This is especially true on systems in
which the generator 
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