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Cornell University 
 Library 
 
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 tine Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31924031225174 
 
AUTOMOBILE 
 LABORATORY MANUAL 
 
yke QraW'MlBook & 7m 
 
 PUBIISHCRS OF BOOKS F O R_/ 
 
 Coal Age " Electric Railway Journal 
 Electrical World v Engineering News-Record 
 American Machinist ^ Ingenieria Intemacional 
 Engineerings Mining Journal ^ Power 
 Chemical 6 Metallurgical Engineering 
 Electrical Merchandising 
 
AUTOMOBILE 
 LABORATORY MANUAL 
 
 PROJECTS FOR THE STUDY OF 
 
 ENGINES, CARBURETORS, ELECTRICAL SYSTEMS 
 
 AND MECHANISMS, THEIR CONSTRUCTION, 
 
 OPERATION, ADJUSTMENT AND REPAIR 
 
 BY 
 
 FREDERICK F. GOOD, A.M. 
 
 Instructor in the School of Practical Arts and in the School 
 of Ediication. Columbia University, New York City 
 
 First Edition 
 
 McGRAW-HILL BOOK COMPANY, Inc. 
 NEW YORK: 370 SEVENTH AVENUE 
 
 LONDON: 6 & 8 BOUVERIE ST, E. C. 4 
 
 1922 ^L'l^NtiLL. 
 
Copyright 1922, by the 
 McGraw-Hill Book Company, Inc. 
 
PREFACE 
 
 The purpose of this outline of experiments is to provide a pro- 
 gressive series of study-units in three groups which will serve as a 
 basis for the organization of laboratory automobile classes for 
 beginners. The course covers a systematic introduction to the 
 automobile mechanisms and a study of their fundamental prin- 
 ciples. It includes practical work, dealing with manipulations, 
 disassembling and assembling of parts, testing for and locating 
 troubles, making adjustments, and doing minor repair work. 
 
 The actual school conditions under which automobile classes 
 must be conducted place certain unavoidable limitations upon 
 the organization and the methods of laboratory work. We may 
 assume that teachers must handle at least fifteen or twenty students 
 in a class. It is also assumed that part of the time of the course 
 will be devoted to discussion, demonstrations, and quiz work, using 
 as a basis one of the automobile textbooks. In the teaching of 
 large groups in automobile laboratory work teachers frequently 
 resort to the squad method, in which the students are instructed 
 and quizzed as a group around the apparatus. In the use of this 
 method students are required to answer specific lists of questions 
 or to write reports on the work. 
 
 In order to provide for the development of self-reUance, skill, 
 and initiative, it is desirable in the automobile course, as in other 
 laboratory courses, to plan for as much individual experimental 
 work as the instructor is able to supervise efficiently. In the 
 author's classes, students are permitted to work in groups of two, 
 but not in larger groups. Many experiments require two people 
 for the manipulation. Individual work is required in the setting 
 up of illustrative apparatus, in operating mechanical and electrical 
 
vi PREFACE 
 
 units, and in disassembling or operating parts of the assembled 
 chassis. Too much emphasis upon the lecture and demonstration 
 methods results in developing a talking acquaintance with the 
 automobile mechanism at the expense of manipulative skill. 
 
 In regard to equipment, the course as outlined herein requires a 
 minimum of two automobiles, — the one a Ford chassis, the other the 
 chassis of one other tjrpical automobile. In the author's laboratory 
 the large automobile is kept in running condition at all times and 
 the engine is not used for disassembling. A flexible metal hose 
 carries the exhaust gases from the muffler to the outside of the 
 building. The front and rear axles of both laboratory automobiles 
 are mounted on wooden stands, permitting the wheels to revolve. 
 
 A i| horsepower gasoline engine mounted on a hand truck is 
 used for preliminary engine study. The laboratory is provided 
 with both gas and direct-current electricity. The gas engine and 
 the automobile engine may be operated either by iUuminating gas 
 or by gasoline. The materials used in the experiments of this book 
 should be regarded merely as a minimum equipment. If neces- 
 sary, automobiles and many special parts may be purchased 
 from a dealer in used cars and used parts. They should, of course, 
 be fairly recent models. Used machines may be cleaned with 
 kerosene or gasoline and painted. The cost of a minimum equip- 
 ment for the course is between $i,ooo and $2,000. 
 
 In the author's laboratory a cabinet of twenty compartments is 
 used for storing special parts required as Materials in the 
 experiments. The compartments are numbered and labeled with 
 the titles of the experiments for which they contain apparatus. 
 An index is posted showing exactly where materials for any par- 
 ticular experiment may be found. Students are required to select 
 their experiments with the approval of the instructor and they are 
 required, at the beginning of the period, to give to the instructor a 
 slip of paper containing their names, the date, and the title of the 
 experiment upon which they intend to work. Students are held 
 responsible for returning the apparatus to the proper cabinets when 
 
PREFACE Vli 
 
 experiments are completed. A complete list of apparatus including 
 cabinets with the names and addresses of dealers and manufac- 
 turers may be found on page 177. 
 
 Reference work has been included as a prominent part of the 
 laboratory course. This provides for training in the use of the 
 standard sources of information in connection with the manipula- 
 tive and experimental exercises. A laboratory reference shelf is 
 provided for the necessary reference books. See reference book 
 list on page 175. 
 
 The author wishes to express to many teachers and students of 
 Teachers College his appreciation for their suggestions and criti- 
 cisms and for their cooperation in reading the manuscript, especially 
 to the following professors: John F. Woodhull, Otis W.- Caldwell, 
 Frederick G. Bonser, Arthur D. Dean, and David Snedden. 
 
 The author is deeply indebted to John B. Bryan and to 
 Edward Trauth, former students, who assisted in the organization 
 and instruction in AutomobUe Mechanics at the time of the War 
 Emergency Courses; to George D. Henck, Supervisor of Manual 
 Arts, Pasadena, California; to Frank C. Panuska, Instructor in 
 Mechanical Drawing, Stujrvesant High School, New York City; 
 and to William H. Stewart, President of the Stewart Automobile 
 School, New York City, for their careful reading of the manuscript. 
 
 Acknowledgment is hereby made to the Macmillan Company 
 for the privilege of using certain line drawings and a part of the 
 text from the author's book Laboratory Projects in Physics, to 
 Professor James A. Moyer for permission to reproduce several 
 illustrations from his Gasoline Automobiles, to the University of 
 Wisconsin Extension Division for the use of several illustrations 
 from Hobbs, ElUottand ConsoHver's The Gasoline Automobile, and 
 to the Van Nostrand Company for the use of illustrations in 
 Frazer and Jones' Motor Vehicles and Their Engines. 
 
 F. F. Good. 
 
 New York, N. Y. 
 June, 1922. 
 
DIRECTIONS FOR STUDENTS 
 
 The introductory experiments of Group I should be performed 
 before taking up work in Groups II and III. Before beginning an 
 experiment get the instructor's approval. Write the title of the 
 experiment, your name, and the date on a slip of paper and give 
 the slip to the instructor. This entitles you to the use of the 
 apparatus necessary for the experiment. In general, students are 
 permitted to work in pairs (not in larger groups). 
 
 The apparatus for some experiments is stored in cabinets. Con- 
 sult the index showing where materials may be found. Many of 
 these pieces of apparatus are expensive. Handle them with 
 extreme care. After an experiment is approved by the instructor 
 students are expected to take the apparatus from the cabiaet to 
 the tables, set it up and operate it according to the directions. If 
 any of the required materials are not found in the proper cabinet, 
 write on a slip of paper the names of the articles needed with your 
 name and give it to the instructor. He wiU then give you the 
 apparatus. When the experiment is finished return the special 
 apparatus, personally, to the instructor and get your slip from 
 him as a receipt for its return. Do not disassemble the apparatus 
 until you are certain that you understand it fully. When an 
 experiment is completed, students are required to disassemble the 
 apparatus and place the parts in the proper cabinets. Your place 
 at the laboratory tables should always be left in good order. 
 
 In doing mechanical work it is very important that students 
 develop habits of careful and orderly procedure. Do not begin an 
 operation until you understand with reasonable clearness what to 
 do. In disassembling apparatus place parts in orderly arrange- 
 ment. Do not use a hammer or other tool that may injure delicate 
 
 i^ 
 
X DIRECTIONS FOR STUDENTS 
 
 parts of apparatus. Learn to use screw drivers and wrenches 
 properly. If you are in doubt about any procedure, consult the 
 instructor. 
 
 A carefully written record of each experiment that is performed 
 should be kept in a loose-leaf notebook of uniform size. Write the 
 title and the number of the experiment, your name and the date 
 at the top of each report. Answer questions in complete sentences 
 according to the numbering in the directions. Make clear diagrams 
 of apparatus. They will help you to understand and remember the 
 important facts of the experiment. Your laboratory report should 
 show to the instructor at a glance whether or not you understood 
 what you were doing. It should also aid you in reviewing the 
 experiment for a test with a minimum expenditure of time. 
 
 Much of the value to be gained from this study of the automobile 
 will depend upon whether you can improve your ability to take 
 apart and put together mechanical units; to make them work 
 properly; to understand how the different parts contribute to 
 the proper functioning of the whole mechanism; to find out what 
 is wrong if they do not work properly; to correct the trouble; 
 and to learn the fundamental principles of their operation. 
 
CONTENTS 
 
 PAGE 
 
 Preface v 
 
 Group I. Expekiments — Introductory Exercises 
 
 1. Automobile Mechanisms — A. Survey Work ... i 
 
 2. Automobile Mechanisms — B. Survey Work . . 4 
 
 3. Automobile Mechanisms — C. Survey Work .... 6 
 
 4. Gasoline Engine — A. Four-stroke ....... 7 
 
 5. Gasoline Engine — ^B. Four-stroke 10 
 
 6. Carburetors — A . . : 1 13 
 
 7. Carburetors — B -1 • iS 
 
 8. Automobile Engine — A. Ford . . : 18 
 
 9. Automobile Engine — B. Ford< 22 
 
 10. Engine-cooling Systems — A 25 
 
 11. Engine-,oiling Systems — A .26 
 
 12. Brake Mechanisms — A . . 28 
 
 13. Introductory Electrical Work — A. The Liquid Cell and the Dry 
 
 Cell 30 
 
 14. Introductory Electrical Work — B. Measuring Voltage (Pressure) 
 
 and Amperes (Rate of Current Flow) 33 
 
 15. Introductory Electrical Work — C. Wiring and Operating Lamps, 
 
 Bells, and Motors . . . ... 36 
 
 16. Introductory Electrical Work — D. Electromagnets, Permanent 
 
 Magnets, and the Electric Bell 38 
 
 17. Electric 'jMotor 41 
 
 18. Electric 'Generator . .44 
 
 19. Ignition Sjtstems — ^A . 46 
 
 20. Ignition Systems — B . 49 
 
 21. Storage Battery — ^A . . -Si 
 
 22. Automobile Electric Circuits — A 55 
 
 23. Automobile Electric Circuits — B 58 
 
 xi 
 
xu CONTENTS 
 
 Group II. Experiments page 
 
 24. Engine-cooling Systems — B 60 
 
 25. Engine-oiling Systems — B 62 
 
 26. Lubrication — Transmission and Chassis 64 
 
 27. Front Axle . . 65 
 
 28. Rear Axle ... 68 
 
 29. Valve Mechanisms — A. Ford Engine 70 
 
 30. Valve Mechanisms — B 72 
 
 31. Ignition Induction Coils . 73 
 
 32. Ignition Systems — C. Storage Battery 77 
 
 i3. Ignition Systems — D. Ford Car ... . . .80 
 
 34. Ignition Systems — E. Low-tension Magneto and Dry Cell 
 
 Battery . . . . . .84 
 
 35. Ignition Systems — F. High-tension Magneto . . . 87 
 
 36. Storage Battery — B 89 
 
 37. Storage Battery — C . . 91 
 
 38. Operating- a Gas Engine. Troubles and Adjustments . 93 
 
 39. Engine Troubles , . . 94 
 
 40. Change Speed Gears — A. Selective .... -95 
 
 41. Change Speed Gears — B. Ford Transmission .... 99 
 
 42. Change Speed Gears — C. Ford Transmission . . loi 
 
 43. Clutches . . 104 
 
 44. Brake Mechanisms — B 108 
 
 45. Compression — A . no 
 
 46. Compression — B . . . 112 
 
 47. Tires — A 114 
 
 48. Tires— B 116 
 
 49. Tires — C . 118 
 
 50. Carburetors — C 120 
 
 51. Carburetors — D 122 
 
 52. Carburetors — E 125 
 
 SS. Carburetors — F , . 129 
 
 54. Fuel Feed Systems 132 
 
 Group III. Experiments 
 
 
 55. Valve Timing — Ford Engine 
 
 . . . .136 
 
 56. Ignition Timing . . ... 
 
 . . . .138 
 
 57. Differential — A. Bevel Gears 
 
 . 140 
 
 58. Differential— B. The Ford 
 
 . 142 
 
 59. Alternating Currents 
 
 . 144 
 

 CONTENTS 
 
 xiii 
 
 PAGE 
 
 6o. 
 
 Ignition Magnetos, Low-tension 
 
 147 
 
 6i. 
 
 Automobile Electric Wiring Circuits — C . 
 
 • 151 
 
 62. 
 
 Automobile Electric Generators 
 
 • IS3 
 
 63. 
 
 Automobile Electric Starting Motors 
 
 . 156 
 
 64. 
 
 Ignition Troubles and Adjustments 
 
 • IS9 
 
 6S. 
 
 Engine Mechanical Parts and Bearings 
 
 . 161 
 
 66. 
 
 Engine Knocks 
 
 162 
 
 67. 
 
 Pistons and Cylinders ... 
 
 . 164 
 
 68. 
 
 Engine Power . . 
 
 . 167 
 
 69. 
 
 Steering Gear, Muffler, Wheels, and Bearings . 
 
 . 169 
 
 70. 
 
 Chassis Arrangement, Frames, and Springs 
 
 . 172 
 
 
 Laboratory Reference Shelp 
 
 • • 17s 
 
 
 Reference Books and Related Books 
 
 ■ • I7S 
 
 
 Charts 
 
 . 176 
 
 
 Apparatus List 
 
 • 177 
 
 
 Index . . 
 
 . 183 
 
AUTOMOBILE LABORATORY 
 MANUAL 
 
 I. AUTOMOBILE MECHANISMS— A. SURVEY WORK 
 Identification of Important Parts and Their Functions 
 
 MATERIALS. Chassis of a typical automobile with rear wheels raised; 
 textbook and reference books. 
 
 Examine the main divisions of the mechanism of an automobile 
 chassis. In the textbook and reference books locate a number of 
 line drawings or sectional illustrations showing the typical auto- 
 mobile mechanism with parts labeled. If possible, examine illus- 
 trations showing both horizontal views and vertical views. Pro- 
 ceed to the laboratory automobile and point out the parts shown 
 in the illustration. The chassis may be divided into parts as 
 follows: (a) the power plant, (b) the power-transmission system, 
 (c) the control system, (d) front and rear axles, (e) the frame and 
 springs. 
 
 1 . State the make and the model of the car that you are studying. 
 
 2. Name in order of size twelve important divisions or parts 
 of an automobile mechanism. 
 
 3. Beginning at the front of the car list the twelve divisions or 
 parts, proceeding from the front toward the rear. When parts 
 are grouped together name them in any order. 
 
 4. State in a sentence the function of each of these twelve parts 
 in relation to the general operation of the car. 
 
Missing Page 
 
AUTOMOBILE MECHANISMS 
 
 Fig. 2. — Plan view of a typical car. 
 
4 AUTOMOBILE LABORATORY MANUAL 
 
 5. According to your judgment name the five heaviest units of 
 the car, omitting the wheels, axles, frame, and body. 
 
 6. Explain briefly in your own language how the following parts 
 are held in position: (a) the engine, (6) the radiator, (c) the differ- 
 ential, {d) the change gears, (e) the carburetor. 
 
 7. Beginning at the starting handle at the front, name in order 
 at least five important parts of the mechanism which connect with 
 the drive-shaft between the crank and the rear axle. If the rear 
 wheels are raised from the floor, crank the engine and observe the 
 operation of the mechanism. Shift the gears. 
 
 8. Describe the location of the following: {a) crankshaft, 
 {b) the carburetor, (c) the universal joint, {d) the cylinders, (e) the 
 clutch, (/) the gearcase, (g) the crankcase, {h) the propeller shaft- 
 
 2. AUTOMOBILE MECHANISMS— B. SURVEY WORK 
 Identification of Parts and Their Functions 
 
 The engine, the cooling system, the carburetor. 
 
 A. The Engine. 
 
 1. How many cylinders has this engine? 
 
 2. What part of the engine moves up and down in the cylinder? 
 
 3. What part of the engine revolves in the crankcase? 
 
 4. Between what two parts of the mechanism is the intake 
 manifold placed? 
 
 5. Between what two parts is the exhaust manifold placed? 
 
 6. Where are the inlet valves located? the exhaust valves? 
 
 B. The Cooling System. 
 
 7. Explain why engine cyUnders are made with double walls 
 for carrying a water-jacket. 
 
 8. From what point on the radiator does water flow toward the 
 engine? 
 
AUTOMOBILE MECHANISMS 
 
 Stee/~/ng Ai~/n 
 
 /yonf /?3(//us Pods 
 
 Steer/ng Posf _ 
 
 Front W/ieef 
 
 Commutator^ 
 
 Sfe eHnty Gean 
 
 Magneto and Transmis s/on 
 
 /fubB/-oA;& 
 
 Assemb/y 
 
 Gas o//ne Feed P/pe 
 
 Rear- Ax/e Bad/us Pod 
 
 £/n cf-Qency 
 
 Brake. 
 
 Differentia/ Gear 
 
 Pear Spring 
 
 from Good's *' Laboratory Projects in Physics." Used 
 by permission of the MacmiUan Company, pubUshefs 
 
 Fig. 3. — ^The Ford car — Location of important parts. 
 
6 AUTOMOBILE LABORATORY MANUAL 
 
 g. How does the water return again to the radiator? 
 
 10. What causes the water to flow? 
 
 11. What is the function of the radiator? 
 
 C. The Carburetor. 
 
 12. Describe the location of the carburetor on this automobile. 
 
 13. What two substances .are mixed in a carburetor? 
 
 14. What valve on the carburetor is operated from the steering 
 wheel? 
 
 15. What valve is sometimes operated from the dash? 
 
 3. AUTOMOBILE MECHANISMS— C. SURVEY WORK 
 
 Identification of Important Parts and Their Functions 
 
 The clutch, the change gears, the differential, the brakes, and 
 the control system. 
 
 A. The Clutch. Operate the clutch. 
 
 1. What two shafts does the clutch connect and disconnect? 
 
 2. State two situations in operating a car when the driver 
 might use the clutch. 
 
 3. How does the driver operate the clutch? 
 
 B. The Gears. Shift the gears. 
 
 4. Between what two parts are the gears located? 
 
 5. Why is it important to have gears on an automobile? 
 
 6. How many speeds has this car? Name them. 
 
 7. What is meant by " gears in neutral " ? 
 
 C. The Differential. If the rear wheels are raised, turn one and 
 note the effect on the other. This mechanism may be studied in 
 detail later. 
 
 8. Where is the differential located? 
 
 9. What trouble would arise in turning a corner if the rear axle 
 were a solid rod from wheel to wheel? 
 
THE GASOLINE ENGINE 7 
 
 D. The Brakes. Operate the brakes. 
 
 10. Where are the brake drums located? 
 
 11. What levers are used for applying friction to the brake 
 drums? 
 
 12. How is the force applied at the levers transmitted to the 
 brakes? 
 
 E. The Control System. 
 
 13. The steering wheel moves the steering knuckles and the tie 
 bar. Locate (a) the steering knuckle and (b) the tie bar. 
 
 14. Get on the car and turn the steering wheel. What is the 
 function of the tie bar? 
 
 4. THE GASOLINE ENGINE— A 
 Proportions of Mixture and Ignition 
 
 MATERIALS. Gas engine; ignition-bottle; large glass jar; rubber tube; 
 induction coil; four dry cells; telephone magneto with small lamp. 
 
 A. The Explosive Mixture. Fill the ignition-bottle with water 
 and invert in the glass jar of water. Attach the rubber tube to a 
 gas cock. Collect a half bottle of gas by displacement over water. 
 Remove the bottle, allowing air to enter, forming a mixture of half 
 gas and half air. Hold your hand over the end of the bottle and 
 invert a few times to mix the air and gas. Remove your hand 
 and bring a lighted match to the mouth of the bottle. Does the 
 mixture burn? 
 
 1. Does a bottle of pure illuminating gas bum more or less 
 readily than half air and half gas? 
 
 2. Vary the proportions of the mixture and determine from the 
 report of the explosion approximately what proportions by volume 
 of air and gas give the most effective explosion. Which gives the 
 better explosive mixture, one-fourth gas or one-fifth gas? 
 
8 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 3. What is meant by the statements that the mkture in an 
 engine is " too rich " or " too lean "? 
 
 B. Ignition, the Magneto and the Induction Coil. The explo- 
 sion in gas engines is caused by a spark from a magneto (electric 
 generator) or from an induction coil Operated by dry cells. Operate 
 a magneto generator, causing it to hght a small lamp. {Caution. 
 
 p/lcup 
 
 .Connectm^ rod 
 
 Cylinder 
 Magneto 
 
 Intake va/ve — 
 £xhaust va/i^e 
 
 Crank 
 Crank sfiafi 
 
 '/"// wheels 
 
 From Good's "Laboratory Projects in Physics." Used 
 by permission of the MacmiUan Company, publishers 
 
 Fig. 4. — A gas or gasoline engine. 
 
 An induction coil is dangerous. Do not touch the secondary terminals 
 after attaching the battery to the primary.) Attach a wire from one 
 secondary terminal of the coil to within a quarter inch of the other. 
 This will form the spark gap. Connect one terminal of the battery 
 of four dry cells to one terminal of the primary of the coil. Touch 
 the other battery terminal to the primary terminal of the coU. 
 The vibrator changes a continuous battery current to an inter- 
 
TEE GASOLINE ENGINE 
 
 mittent current. An intermittent current in the primary causes a 
 very high-voltage current to be induced in the secondary. This 
 high- voltage current produces the spark for the ignition. {Caution. 
 To avoid the possibility of an accidental shock from the secondary 
 terminals always disconnect the dry cells from an induction coil 
 while working with the secondary circuit.) Attach wires from the 
 secondary terminals to a spark plug and operate it. Mount the 
 spark plug in a ring-stand clamp. 
 
 .Bxhausi 
 *m Bxhaust Valvf 
 
 ^^^ Pis for?.. 
 
 Inlet Valve 
 Gas Inkf 
 '•^-Mim'rig Valve 
 •Air Inlet 
 
 Fig. S' — The principal parts of a four-stroke gas engine. 
 
 4. Diagram the wiring, showing induction coil, four dry cells, 
 and spark plug with proper wiring. See Experiment 19. 
 
 A type of induction coil sometimes used in operating a gas 
 engine is the simple " make-and-break " spark coil. It consists 
 of a simple coil of many turns of wire with a soft iron core at the 
 center This small type of coil gives a hot spark when the contact 
 is broken. The igniter mechanism on the side of the cylinder 
 operates the " make-and-break," furnishing a hot spark inside at 
 I the proper time. This is called a " make-and-break " system of 
 ignition. When a spark plug is used as in an automobile it is known 
 
10 AUTOMOBILE LABORATORY MANUAL 
 
 as a " jump-spark " system. The vibrator type of induction coil 
 furnishes a jump spark. 
 
 The electric current for ignition may be produced by a magneto 
 generator which is operated by the engine. As a source of ignition 
 current the magneto is preferable to dry cells since dry cells wiU 
 soon run down and require replacing. 
 
 C. The Engine. Before starting, fiU the cylinder hopper -with 
 water. Oil the cylinder and bearings. This engine may be 
 operated with illuminating gas instead of gasoline. The air and 
 illuminating gas are mixed at the mixing valve. Ask the instructor 
 to start the engine. Keep a safe distance from moving wheels. 
 Observe its operation. Locate the following parts: mixing valve, 
 cylinder, piston, inlet valve, exhaust valve, crankshaft, cam, and 
 cam rod. 
 
 5. Make four diagrams representing the four strokes (half 
 revolutions of a four-stroke engine). Sze Practical Physics, Mil- 
 likan, Gale, and Pyle. 
 
 6. When the inlet opens what causes the explosive mixture to 
 enter the cylinder? 
 
 7. What adjustment must be made at the mixing valve to get 
 efficient working conditions? 
 
 5. THE GASOLINE ENGINE— B 
 
 Operation and Mechanisms 
 
 MATERIALS. One and one-half horsepower gasoline engine on a truck. 
 See illustration of Gasoline Engine A. 
 
 A. Starting the Engine. FiU the cylinder hopper with water 
 and oil the cylmder and bearings. Use illuminatmg gas or gasoline. 
 Before attempting to start the engine throw on the spark-coil 
 lever, close the choker (to increase the suction if gasoline is used), 
 and turn the flywheels over compression. Open the air damper 
 
THE GASOLINE ENGINE 
 
 II 
 
 when the engine begins to fire. If the engine is properly timed, 
 explosion should take place at or near maximum compression. If 
 
 Intake Pipe 
 
 Spark Plug-K 
 
 Carbureter 
 
 Exhaust 
 / Pipe 
 
 \ Exhaust 
 Bases 
 
 Connectinq Rocf-'R 
 
 -CRANK CASE 
 Intake position. Compression position. 
 
 Explosion position. Exhausi position. 
 
 Fig. 6. — The four strokes of an automobile engine. 
 
 you are in doubt about the procedure have an instructor start the 
 engine. {Caution. Keep a safe distance from moving wheels and 
 shafts.) The engine will start more readily if the mixing valve 
 
12 AUTOMOBILE LABORATORY MANUAL 
 
 is opened about two turns to let in a richer mixture at the start. 
 When the engine begins to run, the mixing valve should be screwed 
 farther shut, otherwise the mixture may be too rich and cause 
 smoking at the exhaust. If the mixture is too lean, the engine will 
 misfire, run slowly, or " gasp for breath." 
 
 B. Engine Mechanisms and Their Functions. 
 
 1. Can a four-stroke engine fire every revolution? Explain. 
 
 2. In the four-stroke engine, what is the ratio of the number 
 of teeth on the two gears which operate the cam? 
 
 3. What is the function of the cam? 
 
 4.- Name two parts that are operated by the cam rod. 
 
 5. Examine the governor. What runs it? What does it do to 
 the cam rod when the speed becomes too great? Pull the balls 
 apart and note how this stops the firing when the engine is running. 
 Set the speed lever in high, medium, and low. 
 
 6. What pushes the cam rod toward the crankshaft? What 
 pushes it back? 
 
 7. When the engine is running, note that the cam rod operates 
 a valve by means of a lever at the end of the cylinder. Is this the 
 inlet valve or the exhaust valve? How do you know? 
 
 8. What is the purpose of the other valve? What causes it to 
 open? What causes it to close? 
 
 9. What is the purpose of the water jacket around the cylinder? 
 The water should be withdrawn from it in cold weather when the 
 engine is idle. Why? 
 
 10. When the engine speeds up to maximum, what stops the 
 sparking mechanism? 
 
 11. When the engine speeds up to maximum, what holds the 
 exhaust valve open? 
 
 12. When the exhaust valve is kept open, does the piston draw 
 in mixture through the inlet valve? Explain. 
 
 13. Why do gas engines need heavy flywheels? 
 
 14. After stopping the engine, throw out the switch at the spark 
 
CARBURETORS 13 
 
 coil in order to avoid wasting the battery current. In what 
 position would the make-and-break mechanism need to stand to 
 exhaust the batteries? 
 
 6. CARBURETORS— A 
 The Principle and Construction of a Carbixretor 
 
 MATERIALS. Bunsen burner; ignition-bottle; large glass jar; one or 
 more sectional carburetors. 
 
 A. Preliminary Work. The purpose of a carburetor is to mix 
 air and gasoline vapor in the proper proportion to obtain efficient 
 combustion. 
 
 Note that a Bunsen burner has two adjustments — one for con- 
 trolling the gas flow and one for controlling the air flow. The 
 purpose of these adjustments is to mix air and gas in proper pro- 
 portion before they reach the flame. A Bunsen burner is a car- 
 buretor. 
 
 1. Close the air inkt completely and light the burner. The 
 flame is now operating with a " rich mixture " — insufficient supply 
 of air. Describe the flame under these conditions. 
 
 2. Gradually open the air inlet of the burner until sufficient 
 air is admitted to cause the flame to " strike back " to the bottom of 
 the burner tube. This sometimes occurs in an automobile engine 
 when the explosion " sneezes back " into the carburetor. Do not 
 permit it to burn for more than a moment at the bottom. Describe 
 the flame when the air inlet is open. 
 
 3. Fill the ignition-bottle with water and invert it in the jar 
 of water. Allow illuminating gas from a rubber tube to bubble 
 into the bottle, displacing the water. When the bottle is filled 
 with gas, remove it and ignite the gas in the bottle with a match. 
 In the same way remove the bottle when it is half full of gas, 
 allowing air to mix with the gas so that you have a mixture of half 
 
14 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 gas and half air. Try one-fourth gas and also one-fifth gas. 
 Which bums most vigorously or forcefully? 
 
 B. Carburetor Mechanism and Function. Excunine a car- 
 buretor in section. The common types of carburetors consist of 
 two main compartments — the float chamber and the mixmg 
 
 Air/n/ef 
 
 Geso/ine 
 In/et 
 
 From Good's "Laboratory Projects in Physics." Used 
 by permission of the MacmiUan Company, publishers 
 
 Fig. 7. — A carbureter showing spray needle and auxiliary air inlet. 
 
 chamber. The purpose of the float chamber is to hold a supply 
 of gasoline from the tank ready for use in the mixing chamber. 
 It must keep this supply at an approximately constant level. The 
 purpose of the mixing chamber is to provide for mixing a fine 
 spray of gasoline with the air as it is drawn through the carburetor 
 by the suction of the engine. In answering questions refer to 
 Motor Vehicles, Frazer and Jones (chapter on Elements of Carbure- 
 
CARBURETORS le, 
 
 tion); Gasoline Automobiles, Moyer, or The Gasoline Automobile, 
 Hobbs, Elliott and Consoliver. 
 
 4. What is the purpose of the float? 
 
 5. What is the function of the float needle? 
 
 6. Of what material is the float made? 
 
 7. Explain the sequence of operations which cause gasohne to 
 enter from the tank into the float chamber (gravity system). 
 
 8. What causes gasohne to stop flowing from the tank? 
 
 9. What might cause a carburetor to flood (overflow)? 
 
 10. What is the function of a spray needle? 
 
 11. If the spray needle is too far closed, how is the mixture 
 affected and vice versa? 
 
 12. Where is the choker or choke valve located, and what is its 
 function? 
 
 13. How is it possible to obtain a richer mixture by means of the 
 choker? 
 
 14. What is the function of the throttle? 
 
 15. Why does the mixture tend to become very lean when the 
 throttle is nearly shut? 
 
 16. For what purpose is wire gauze used at the entrance to the 
 float needle valve? 
 
 17. What is the purpose of the drain cock at the bottom of the 
 carburetor? 
 
 18. What is a Venturi tube? See Motor Vehicles, Frazer and 
 Jones. 
 
 7. CARBURETORS— B 
 Construction, Operation, and Adjustments 
 
 MATERIALS. A number of different makes of carburetors repres^^nting 
 types with eccentric and with concentric float chaml^ers. If possible, have one 
 or more carburetors in section. Used carburetors are satisfactory. 
 
 A. Carburetion. When automobiles were first introduced, 
 high-grade gasoline (volatile gasoline) was very cheap. Because 
 
i6 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 the gasoline vaporized readily, carburetors were made in very 
 elementary form — surface carburetors. As the demand for fuel 
 increased, and with it the necessity for including in the fuel some 
 of the heavier distillates, the problem of carburetor design and 
 construction became more complex. Besides changes in the 
 nature of the fuel, the demand arose for carburetors which would 
 provide a more efficient mixture for wider variations in engine speed. 
 
 •^^'^ir Valve 
 
 " /?/> Ya/ve 
 •Spring 
 
 Counter—.^. 
 Weight — 
 
 Air Valve Spring 
 TAdjusHngScrevr 
 
 fAir Valve 
 LiftAc^uslment 
 
 -Needle Vahe PachirigNut' 
 cr~ Gasoline AdJi^Hn^ i/eedle Valve 
 
 Fig. 8. — A carbureter with auxiliary air port and with concentric float chamber. 
 
 All simple forms of carburetors produce rich mixtures at high 
 speed. If the mixing valve is set for high speed, the mixture is too 
 lean for low speed. A simple carburetor that will produce a well- 
 balanced mixture for all speeds has not yet been devised. Properly 
 proportioned mixtures for the different speeds can be obtained 
 approximately with comphcated carburetors containing properly 
 
CARBURETORS 1 7 
 
 designed and adjusted auxiliary air valves. These carburetors are 
 accordingly more expensive. 
 
 B. Reference Work. Use Motor Vehicles, Gasoline Automo- 
 biles, and The Gasoline Automobile. 
 
 1. What general type, of carburetor is most commonly used at 
 the present time? 
 
 2. Approximately what proportions by weight of air and 
 gasoline give the best combustible mixture? 
 
 3. What proportions by weight give (a) the upper limit of com- 
 bustion? (b) the lower limit of combustion? 
 
 4. Name four valves that may be found on many carburetors. 
 
 5. How does opening the throttle cause more air and gasoline 
 mixture to flow? 
 
 6. Diagram a carburetor containing an auxiliary air port. 
 
 7. How does a metering pin differ from the ordinary spray 
 needle? 
 
 8. What is meant by " concentric float chamber " and by 
 " eccentric float chamber " ? 
 
 9. State an advantage of the concentric type. 
 
 10. Should the float chamber of a carburetor be closed tight or 
 should it have an opening in the top to let in air? Explain. 
 
 1 1 . Why is the spray nozzle usually placed in a Venturi tube? 
 
 C. Carburetor Adjustment. 
 
 12. What is meant by " adjusting a carburetor " ? 
 
 13. Name two valves common to many carburetors which 
 usually require adjustment. 
 
 14. State six conditions that are necessary before making ad- 
 justments. See Motor Vehicles. 
 
 For a study of carburetor adjustments see experiments, Carbu- 
 retors C, D, E, and F. 
 
l8 AUTOMOBILE LABORATORY MANUAL 
 
 8. AUTOMOBILE ENGINE— A 
 The Construction and Operation of the Ford Engine 
 
 MATERIALS. Ford chassis, (used car — radiator, cylinder head, and 
 one piston removed); reference books, The Model T Ford Car, Pag^, and 
 The Ford Manual. 
 
 The most expensive and largest single unit of the automobile 
 mechanism is the engine. Upon its design, material, and workman- 
 ship the efficiency of operation depends. An engine that is 
 defective in design or adjustment may be very wasteful of gasoline. 
 If the parts of the engine include cheap material and cheap work- 
 manship, its life may be only half as long as it should be. The 
 modern gasoline engine has required years of experimentation and 
 the labors of many expert engineers. To appreciate it properly, 
 an automobile driver should thoroughly understand its mechanical 
 parts and the principles of their operation. The Ford engine has 
 become famous because it is powerful for its size, it is efficient in 
 the use of gasoline, and it stands up well under hard service. 
 
 A. Mechanism and Operation. This is an L-type motor. 
 (Inlet and exhaust valves are on the same side. The T-type 
 engine has intake on one side and exhaust on the opposite side.) 
 In answering questions refer to Ford Manual and to The Model T 
 Ford Car, Page. 
 
 1. Are these cylinders cast as a single unit (block) or in parts? 
 
 2. How many shafts are inclosed in the crankcase? Name 
 them. What are their purposes? 
 
 3. How are the inlet and exahaust valves operated? 
 
 4. What operates the camshaft? 
 
 5. How many cams are on the camshaft? 
 
 6. How fast does the camshaft revolve with respect to the rate 
 of the crankshaft? 
 
AUTOMOBILE ENGINE 
 
 19 
 
 ^'.^ 
 
 13 
 
 15: C: 
 
 [£ 
 
 s ^ 
 
 
 tj 
 
 
 O;'^ 
 
 
20 AUTOMOBILE LABORATORY MANUAL 
 
 7. What pushes the valves open? 
 
 8. What closes the valves? 
 
 9. What is the direction of motion of any piston, (a) when 
 its inlet valve opens, {b) when its exhaust valve opens? 
 
 10. What important part of the ignition system is attached to 
 the cylinder head? 
 
 VALVES 
 
 CRAliK SHAFT . 
 
 Fig. 10. — Phantom view of the Ford engine, showing timing gears, camshaft and 
 
 mechanism. 
 
 B. The Crankshaft. Look into the open cylinder and observe 
 the crankshaft. Have some one crank the car and you will note 
 that the crankshaft revolves. 
 
 11. How many main bearings has the Ford crankshaft? 
 
 12. At what angle do the cranks stand with respect to each 
 other in a four-cylinder engine? " 
 
 13. How is the power transmitted from the combustion chamber 
 to the crankshaft? 
 
AUTOMOBILE ENGINE 
 
 21 
 
 14. How are the crank bearings and the pistons oiled? 
 
 15. Name four important parts of the mechanism between the 
 crankshaft and the rear wheels. 
 
 C. The Pistons. One of the pistons has been removed for inspec- 
 tion. The connecting rod connects the piston to the crank-shaft. 
 
22 AUTOMOBILE LABORATORY MANUAL 
 
 i6. How does a well-oiled piston aid compression? 
 
 17. How many rings has the Ford piston? 
 
 18. What is the purpose of the piston rings? 
 
 19. What kind of combustible mixture tends to deposit carbon 
 on the piston and valves? 
 
 20. What causes old pistons to leak and lose compression? 
 
 9. AUTOMOBn>E ENGINE— B. FORD 
 
 MATERIALS. Same as in Ford Engine — A. Reference book, The Model T 
 Ford Car, Pag6. 
 
 A. Ignition. Remove the timer cap. The purpose of the 
 timer is to regulate the time at which current is sent to each 
 induction coil and consequently to each spark plug. 
 
 1. To which shaft is the timer attached? 
 
 2. How many contact points does the timer have? 
 
 3. What touches these points, sending currents to the induc- 
 tion coils and spark plugs? 
 
 4. How many sparks are produced in this four-cylinder engine 
 for each revolution of the crankshaft? 
 
 5. Where is the magneto generator located in the Ford? 
 
 6. What is the sequence of firing in the cyUnders, beginning 
 at the front as No. i? (Same as the sequence of opening of inlet 
 valves.) 
 
 B. The Cooling System. (Thermo-siphoh.) The Ford cylin- 
 ders are cooled by convection. Examine the openings between 
 the walls of the cylinder for water circulation. 
 
 7. Why is it necessary to have a cooling system? 
 
 8. What would be some of the results if the engine were 
 operated without water in the cooling system? 
 
 9. In which direction does the water flow? 
 
 10. Explain what causes the water to circulate. 
 
AUTOMOBILE ENGINE 
 
 23 
 
 11. State two possible causes of trouble in the cooling circuit. 
 
 12. Name two chemicals that are commonly used to prevent 
 freezing in winter? 
 
 C. Lubrication. The life of an automobile engine depends 
 upon proper lubrication of the working parts. Automobile engine 
 
 Cylindtf InUi Cofincciion 
 
 Fig. 12. — Ford cooling system. 
 
 pistons move at rates as high as one thousand to fifteen hundred 
 feet per minute. The metal of the pistons, piston rings, and the 
 cylinder wall wiU rapidly wear away unless a proper supply of oil 
 is provided. 
 
 13. Explain the operation of a splash system of oiling. 
 
 14. What provision has the Ford for circulating the oil? 
 
 15. In what part of the crankcase does the oil stand? 
 
24 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 i6. If the engine should become overheated, what would be the 
 effect upon the engine oil? 
 
 
 
 
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 N 
 
 
 , ' " i 
 
 
 HHi^ 
 
 B ■ ^j 
 
 is- 
 
 " 
 
 O/i ryB£ 
 
 Wm^iti-*% ■ |„„„„-,~i 
 
 "^i^-f^' 
 
 
 p 1 1 
 
 
 
 .-• 
 
 
 ■An^hSB 
 
 -il : 
 
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 ^^--^ 
 
 •ill 
 
 '-«'! 
 
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 p^ ' 
 
 "■=lw' 
 
 '^' '^Si 
 
 ~ ■ 
 
 
 ^^ 
 
 \ \ 
 
 ! 
 
 ^S 
 
 1 feiii 
 
 
 ....«^.™^.^™iJI 
 
 17. What parts of a crankshaft need oil? 
 
 18. What parts of a piston connecting rod need oil? 
 
ENGINE COOLING SYSTEMS 25 
 
 D. The Manifolds. Note the position of the intake manifold 
 which carries the combustible mixture from the carburetor to the 
 inlet valves. The exhaust manifold carries the burnt gases from 
 the exhaust valves toward the muffler. 
 
 10. ENGINE-COOLING SYSTEMS— A 
 
 Air-cooling and the Thermo-siphon System 
 
 The firing of the mixture in a gas engine produces a temperature 
 of between 2,000° and 3,000° F. The engine must be provided 
 with some form of cooling system to prevent it from becoming 
 overheated. Excessive temperatures would result in, carbonizing 
 and burning of the lubricating oil, warping of the metal parts, the 
 rapid wearing away of the pistons and cylinders, and expansion of 
 the mixture with the consequent loss of power. Strange as it may 
 seem, more power is lost in an automobile in heating the cooling 
 system than is utilized in driving the car. About one-fourth of 
 the energy of the combustion is expended in driving the car. 
 The rest is lost mainly through the exhaust and in heating the 
 cooling system. 
 
 A. Air-cooled Engines. 
 
 1. Upon what conditions does cooling in the case of air-cooled 
 engines depend? See The Gasoline Automobile or Motor Vehicles. 
 
 2. How is greater surface for air cooling obtained in the con- 
 struction of motor cycle and other air-cooled engine cylinders? 
 
 3. Are large or small engines more suitable for air cooling? 
 Why? 
 
 4. State two common objections to air-cooled engines. 
 
 B. The Thermo-siphon Cooling System. 
 
 5. For efficient operation, approximately what is the proper 
 
26 AUTOMOBILE LABORATORY MANUAL 
 
 temperature of the water surrounding the engine cylinder? See 
 Motor Vehicles. 
 
 6. How does a thermo-siphon system differ from a pump 
 system? 
 
 7. Does the water in a thermo-siphon system flow upward 
 through the engine or downward? Why? 
 
 8. Beginning at the cylinder head, name all parts of the Ford 
 thermo-siphon system which the water touches in making a com- 
 plete circuit. See Ford Manual. 
 
 9. Examine the Ford engine with cylinder head removed. How 
 many openings carry water from the water jacket of the cylinder 
 casting to the cylinder head? 
 
 10. In the Ford how is the outlet from the cylinder head attached 
 to the radiator? 
 
 1 1 . How is the cylinder inlet connected to the outlet from the 
 radiator? 
 
 12. Measure the approximate thickness of the water space 
 around the Ford cylinder. Measure the approximate thickness 
 of the cylinder wall. 
 
 13. Where is the drain cock on the Ford cooling system located 
 and what is its function? 
 
 14. State two advantages of a thermo-siphon cooling system and 
 two objections to it. See Motor Vehicles. 
 
 15. Name two types of radiator construction and briefly explain 
 each. See The Gasoline Automobile or Motor Vehicles. 
 
 II. ENGINE-OILING SYSTEMS— A 
 Removing the Oil from the Engine and Refilling 
 
 MATERIALS. Two pails; a quart measure; strainer-funnel. 
 
 The lubricating oil of a gas engine is gradually decomposed by 
 the heat generated in the cylinders. In order to keep the level 
 
ENGINE OILING SYSTEMS 27 
 
 of the oil in the crankcase at the proper height, it is necessary to 
 add new oil as the old is used up. One of the products of decompo- 
 sition of the oil is carbon. This deposits in the bottom of the crank- 
 case. At regular intervals it is necessary to clean out this black 
 residue which sometimes contains small particles of metal. Read 
 in Motor Vehicles the part of the chapter on Lubrication dealing 
 with draining and cleaning the crankcase. Place a galvanized 
 pail under the engine of an automobile in such position that it is 
 directly beneath the drain plug in the bottom of the oil reservoir. 
 Remove the plug and drain the oil into the pail. 
 
 1 . Is all of the oil removed in this way? Is all of the sediment 
 removed? 
 
 2. Describe the usual method of removing the latter. See 
 Motor Vehicles. How frequently should the cylinder oil be 
 removed and the crankcase cleaned? 
 
 Note: Since this engine has not been operated sufficiently to 
 necessitate the " flushing " of the oiling system with kerosene, this 
 step may be omitted. Replace the plug in the crankcase. Do not 
 omit the plug gasket or washer. Screw the plug tight enough to 
 prevent leakage. Have this job inspected by the instructor before 
 proceeding further. 
 
 3. What is the purpose of a plug gasket? Strain the oil, using 
 the second pail, a small measure and strainer-funnel, and pour 
 the strained oil into the engine through the fiJling tube provided 
 for that purpose. 
 
 4. Keep a record of the number of quarts put in. How many 
 quarts of oil should this engine have? See Instruction Book. 
 Special care must be exercised to avoid spiUing the oil on the car 
 and on the floor. Place the pail under the drain plug as a pre- 
 caution in case of leakage. Have this job inspected by the instruc- 
 tor after the oil is put into the engine. 
 
 5. How can you tell when enough oil has been put in? 
 
28 AUTOMOBILE LABORATORY MANUAL 
 
 6 . What means is provided on a Ford engine for determining the 
 proper level of oil in the crankcase? See Model T Ford Car. 
 
 7. Would an excess of oil do any harm? See Motor Vehicles. 
 
 8. What might happen if the oil level were allowed to get 
 too low? 
 
 9. How does an excessive amount of lubricating oil manifest 
 itself? See The Gasoline Automobile under Lubricating Troubles. 
 
 10. Describe fully how you would clean and replenish the oiling 
 system of the Ford. See Model T Ford Car. 
 
 11. How often should the oiling system of the Ford be " flushed 
 out " ? 
 
 12. What kind of oil should be used in an automobile engine? 
 See The Gasoline Automobile or Motor Vehicles. 
 
 13. What is meant by the following terms relating to lubricat- 
 ing oils: (a) flash point ; (b) fire point; (c) cold point? 
 
 12. BRAKE MECHANISMS AND ADJUSTMENTS— A 
 
 Removing the Ford Rear Wheel and Study of the Brake Mechanism 
 
 Brakes employed for retarding or stopping the car are usually 
 attached to the rear wheels. A cylindrical metal part called the 
 brake drum is attached to the wheel. Against this drum a steel 
 band may be drawn or released by force apphed at the brake pedal 
 or brake lever. The brake very commonly contains two bands, 
 one which compresses against the outside and one which expands 
 against the inside. There are, therefore, two general classes of 
 brakes — external contracting and internal expanding. Read text- 
 book on brakes. 
 
 A. Removing the Rear Wheel of the Ford Car. With a 
 wrench take o5 the hub cap and the retention or clamping nut 
 from one of the rear wheels of the Ford. Remove the wheel from 
 
BRAKE MECHANISMS 
 
 29 
 
 the hub. Lay all parts aside in good order for reassembling. 
 Have this work approved by the instructor. 
 
 I. 
 nut? 
 
 What is the reason for using a cotter pin in the retention 
 
 2. What is the purpose of the key which stands in the hub and 
 axle grooves? In replacing the wheel do not omit the key. 
 
 3. If the key were not in place would it be possible to brake 
 the car? Explain. 
 
 ^x/e Housing Cap 
 
 Hub Brake Ca/ij 
 Axle^haft- 
 Hub Brake Shoe 
 
 Drum 
 
 Fig. 14. — Ford emergency brake. 
 
 4. If the key were not in place would it be possible to drive 
 the car? Explain. 
 
 B. The Brake Mechanism. 
 
 5. To which of the two general types of brakes does the Ford 
 rear-wheel brake belong? 
 
 6. Diagram one type of external contracting mechanism and 
 one type of internal expansion mechanism. See Experiment 44. 
 
 7. With a wrench remove the brake shoe. Have this work 
 approved, then replace it. Name at least five important parts 
 of the brake mechanism. 
 
30 AUTOMOBILE LABORATORY MANUAL 
 
 8. What causes the brake shoe to expand against the drum 
 and what causes it to release? 
 
 9. Observe the hand-brake lever which operates the emergency- 
 brake mechanism. By what means is the force carried from the 
 brake lever to the expander shaft? See Model T Ford Car. 
 
 10. If the brake shoe becomes worn and does not engage tightly 
 against the drum, what adjustments may be made to cause it to 
 engage properly? 
 
 11. Note that the foot brake on the Ford tightens a brake band 
 on the transmission mechanism. Is this a contraction brake or an 
 expansion brake? 
 
 12. Which of the three drums on the transmission is the service 
 brake drum? 
 
 13. Explain how applying the emergency brake also throws out 
 the clutch. 
 
 13. INTRODUCTORY ELECTRICAL WORK— A 
 The Liquid Cell and the Dry Cell 
 
 MATERIALS. Base block 5X5X2 ins.; round battery-jar s| ins. high 
 by 2j ins. in diameter; ammonium chloride (sal am»moniac); zinc battery rod; 
 carbon rod from an old dry cell; Bunsen burner; electric bell; No. 24 insulated 
 wire; jar of 10 per cent nitric acid, to be used only by the instructor; cardboard, 
 for separating battery rods at top; short glass tube, for separating battery 
 rods at bottom; glass stirring rod. 
 
 A. Making a Leclanche Liquid Cell. Make up an ammonium- 
 chloride solution by filling the battery jar one-fifth full of ammo- 
 nium-chloride salt and adding water till the top of the liquid 
 stands i inch from the top of the jar. Dissolve by stirring with a 
 glass rod. Place the zinc rod in the solution at one side of the jar, 
 and the carbon rod at the other. Use a short piece of glass tubing 
 at the bottom of the jar and carboard at the top to keep the 
 electrodes separated. See instructor's model. 
 
INTRODUCTORY ELECTRICAL WORK 
 
 31 
 
 1 . Connect wires to the electrodes and ring an electric bell. 
 
 2. Make a drawing of the cell indicating the materials used, and 
 showing the direction in which the current flows. The current is 
 considered as flowing from the positive to the negative electrode 
 outside the solution. The negative electrode is the one acted 
 upon more by the electrolyte. In this case the zinc is negative. 
 
 Card-board to Aeep 
 rods separated 
 st too. 
 
 Carbon rod- 
 
 From Good's " Laboratory Projects in Physics." Vied 
 by permission of the MacmiUan Company, publishers 
 
 Fig. 15. — A liquid cell — ammonium chloride. 
 
 B. Polarization. When this cell is attached to the electric bell 
 it rings the bell for a short time and gradually becomes exhausted. 
 This phenomenon is due to polarization. Hydrogen molecules 
 are set free as a result of the chemical action. The carbon electrode 
 gradually becomes covered with a thin film of hydrogen, which 
 prevents the flow of the current. Polarization may be counteracted 
 
32 AUTOMOBILE LABORATORY MANUAL 
 
 by placing in contact with the carbon electrode some form of 
 oxidizing agent, as, for example, manganese dioxide. The hydro- 
 gen reacts with the manganese dioxide, forming water. This cell 
 may be temporarily depolarized by heating the carbon rod in a gas 
 flame for three minutes. It- may be depolarized more effectively 
 by heating it for three minutes and holding it for about a minute, 
 while hot, in a solution of lo per cent nitric acid. ( Note. Nitric 
 acid is a strong oxidizing agent. It is also a strong acid. It will 
 discolor and destroy clothing.) Hold the carbon rod in a gas flame 
 for about three minutes. The instructor will then depolarize it 
 for you in nitric acid. 
 
 3. What depolarizer or oxidizing agent is used in the construc- 
 tion of dry cells? See Practical Physics, Millikan, Gale, and Pyle. 
 
 4. What is the voltage of an ammonium-chloride cell? The dry 
 cell is a form of the ammonium-chloride cell. Large cells have the 
 same voltage as small ones. See Millikan, Gale, and Pyle, 
 LeclanchS Cell. 
 
 5. Connect your cell in series with the cell made by some other 
 student or with a dry cell. How many volts should two cells in 
 series have? Refer to text. 
 
 6. Operate an electric bell by means of two liquid cells in series. 
 What evidence have you that the voltage of two cells is able to 
 force more current through the resistance of the bell than one? 
 
 7. Describe briefly the construction of a simple liquid cell which 
 uses sulphuric acid as the electrolyte. Diagram it. Refer to a 
 physics text. 
 
 8. What is meant by local action? See textbooks. 
 
 9. Diagram a dry cell and name the parts. 
 
 C. The Dry Cell. The dry cell is a modification of the 
 Leclanche cell. The negative electrode is a zinc can containing 
 a carbon rod at the center. Between the zinc and the carbon 
 there is a damp mixture of ammonium chloride, zinc chloride, sand, 
 manganese dioxide, etc. The manganese dioxide is a depolarizer. 
 
INTRODUCTORY ELECTRICAL WORK 
 
 33 
 
 The top of the can is then sealed with pitch to prevent the so-called 
 dry cell from really becoming dry. If the pitch is cracked, or if 
 holes are made in the zinc so that the moisture dries out, the cell 
 becomes useless. The voltage of a dry cell remains fairly constant 
 whether it is new or nearly discharged. The amperage will vary 
 widely, depending upon age and usage. When a dry cell is short- 
 circuited, the stored-up energy produces heat in the wires and in 
 the cell. At present the dry cell has largely replaced the older 
 forms of liquid cells. 
 
 ZincTermmal^ Carbon orTermina! 
 
 TarCompgum/ 
 
 PowdtreJ 
 
 Cai-btnancf! 
 
 Manjanesei 
 
 Htshbaard 
 Casing 
 
 Fig. i6. — Cross-section of a dry cell. 
 
 14. INTRODUCTORY ELECTRICAL WORK— B 
 Measuring Volts (Pressure) and Amperes (Rate of Flow) 
 
 MATERIALS. Two dry cells; No. 24 copper wire (insulated); battery- 
 voltmeter; 3S-anipere battery ammeter; push-button. 
 
 A. Making Measurements. Attach two wires firmly to the 
 bmding posts of one of the cells, taking care that the two wires do 
 
34 AUTOMOBILE LABORATORY MANUAL 
 
 not touch each other and cause a short circuit. (A short circuit 
 would heat the wires and rapidly waste away the energy of the 
 cell.) Attach one wire to one of the voltmeter binding posts. 
 Connect the other wire to one side of the push-button. From the 
 other side of the push-button connect a wire to the second post of 
 the voltmeter. Now push the button and read the voltage of the 
 dry cell. In the same way measure the voltage of the second cell. 
 {Caution. In measuring amperes, the 25-ampere ammeter must be 
 connected in series with a push-button in order to avoid wasting the 
 current.) Connect one wire from the cell to the push-button and 
 to one post of the meter. Hold the other wire firmly against the 
 
 .^^1_/-^ 
 
 ^^ 
 
 Orj/Cel/ Push-BuHon Bafferu Ammeter 
 
 or yolimetsr 
 
 Fig. 17. — Wiring for measuring voltage or for testing the.amperage of a dry cell. 
 
 other post and push the button /or a moment. Note the total 
 amperage output of each cell on short circuit. Connect the two 
 cells in series according to instructor's directions, and measure the 
 voltage, then measure the output in amperes with the 35-ampere 
 ammeter and push-button. When you have finished workmg with 
 dry cells take the wires off immediately to avoid accidently short-cir- 
 cuiting them. Screw the top off the push-button and examine it. 
 
 1. Make a table with two columns, one for volts and one for 
 amperes. Record voltage and amperage output of cell No. i 
 cell No. 2, the two cells in series, and three cells in series. (Note: 
 These meters give only approximate readings.) 
 
 2 . What is the correct voltage of a Leclanche cell? Same as dry 
 ceU. See Practical Physics, MiUikan, Gale, and Pyle. 
 
INTRODUCTORY ELECTRICAL WORK 35 
 
 B. Meters. {Caution. Sensitive voltmeters and ammeters are 
 easily ruined by attaching them to currents of too high voltage or 
 too high amperage.) Expensive meters have very delicately bal- 
 anced indicators. Ammeters should always be connected in series 
 with some instrument as a lamp or motor, except in special cases 
 like measuring the output of the dry cell with a meter of high- 
 amperage scale. 
 
 3. What might happen to an ammeter which registers only 5 
 amperes (5-ampere scale) if it were attached to a new dry ceU or 
 to the loo-volt line without a lamp or some other instrument in 
 series for resistance? A lamp or motor offers resistance and per- 
 mits only a small amount of current (amperes) to flow. 
 
 4. Make a diagram showing how an ammeter should be con- 
 nected with a lamp or other resistance in series to prevent ruining 
 (short-circuiting) the ammeter. 
 
 5. How many dry cells are needed to supply 12 volts? 
 
 6. Diagram the proper number of cells in series to operate one 
 6-volt lamp by means of a push-button in the circuit. 
 
 7. Operate a 3-volt lamp by means of dry cells. Diagram the 
 proper number of cells to operate two 3-volt lamps in parallel by 
 means of a single push-button. 
 
 C. Cells in Parallel. For special purposes dry cells are some- 
 times connected in parallel (positive to positive and negative to 
 negative). This produces the effect of a single cell of very large 
 electrodes. The voltage is the same as that of one cell, but the 
 amperage is increased according to the number of cells used. 
 
 7. Diagram a circuit containing three cells in parallel, operating 
 three i|-volt lamps. 
 
36 AUTOMOBILE LABORATORY MANUAL 
 
 15. INTRODUCTORY ELECTRICAL WORK— C 
 
 Wiring and Operating a Miniature Electric Light and Power 
 System and Measuring the Current 
 
 MATERIALS. Two ring stands; two clamps; two crossbars of wood 
 each s ins. long; two dry cells; No. 24 copper wire (insulated); three 3-volt 
 lamps; small 3-volt motor; electric bell; battery voltmeter; 3S-ampere 
 battery ammeter; push-button. 
 
 A. Setting up a Miniature Wiring System. Using two ring 
 stands as supports, attach two wooden crossbars by means of 
 clamps. See instructor's model of the apparatus. To these cross- 
 bars lead two No. 24 insulated wires, each about i yard long. They 
 should be fastened to holes in the crossbars. Attach these wires 
 to the set of two cells connected in series. Care should be taken 
 to keep the free ends of the wires from touching each other. With 
 a knife remove the insulation from the wires at two opposite points, 
 and hang a 3-volt lamp across. You will find that this lamp 
 does not let through as much current (amperes) as the cells can 
 produce. Each lamp requires about \ ampere or less. The 35- 
 ampere ammeter is not sensitive enough to measure the current 
 used by a single small lamp. 
 
 1. How many amperes would three such lamps use? Attach 
 three lamps in parallel on the line wires. Disconnect one of the 
 wires at the battery and attach the ammeter in the circuit. See 
 if three lamps cause it to register any current flow. 
 
 2. If the total output of the two cells is 15 amperes, how many 
 such lamps could be operated at one time? Of course the battery 
 would not last long at this rate of current consumption. 
 
 B. Operating a Motor and a Bell. Operate a small electric 
 motor from your line current. 
 
 3. Connect the ammeter in series with the motor and note how 
 much current it allows to pass through. 
 
INTRODUCTORY ELECTRICAL WORK 
 
 37 
 
38 AUTOMOBILE LABORATORY MANUAL 
 
 4. How many such motors could be operated at one time with 
 a set of cells delivering 10 amperes? 
 
 Attach an electric bell with a push-button to the line and operate 
 it. An electric door bell usually requires about 3- ampere and 3 
 volts. 
 
 5. Which is more expensive — to ring a bell or to light a lamp 
 of the type used above? Why? 
 
 6. How many dry cells are necessary to produce 3-volts press- 
 ure? Six- volts pressure? Nine- volts pressure? How should they 
 be connected — in series or in parallel? 
 
 7. How might a cell or set of cells be short-circuited and the 
 current wasted? 
 
 8. With respect to amperes, what does a short circuit mean? 
 
 9. With respect to length of wire, how could a short circuit be 
 avoided? 
 
 10. With respect to kind of conductor, how could a short circuit 
 be avoided? What is meant by high-resistance wire or a high- 
 resistance lamp? 
 
 16. INTRODUCTORY ELECTRICAL WORK— D 
 Electromagnets, Permanent Magnets, and the Electric Bell 
 
 MATERIALS. Two dry cells; 4 ft. No. 24 insulated wire; large iron nail; 
 small nails; compass; steel knitting rod; push-button; electric bell. 
 
 A. Magnets. Wind the wire around an iron nail, making 
 about fifteen or twenty turns, connect it in series with the push- 
 button and note the effect on the small nails when the ends of the 
 wire are touched to a dry cell. {Caution. Do not let the current 
 flow through this short wire for more than a moment, as it would 
 soon ruin the dry cell.) With a compass, test for N and S poles 
 of the magnet. The south pole of the coil will attract the north 
 
INTRODUCTORY-ELECTRICAL WORK 
 
 39 
 
 pole of the compass. Reverse the direction of current by inter- 
 changing the ends of the wireson the dry cell and retest for poles. 
 
 1. How is the polarity affected by reversing the flow of current? 
 
 2. Does a soft-iron nail retain its magnetism when the current 
 ceases? 
 
 J7 
 
 JJry ae// 
 
 From Good's *' Laboratory Projects in Physics " Used 
 by permission of the Macmillan Company, publishers 
 
 Fig. 19.— Apparatus for the study of magnetism. 
 
 3. State the law which applies to the attraction and repulsion 
 of poles. This law, discovered by Oersted, in 1819, has been 
 applied in the invention of such instruments as the electric bell, 
 telegraph, telephone, dynamo, motor, etc. 
 
 Place a hard-steel knitting rod, or old file, in a large coil and send 
 direct current from the no-volt line, a storage battery, or dry 
 cells through the coil. Withdraw, and test it for magnetism. 
 
40 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 4. What can you say of its permanency? Refer to texts. 
 
 5. Should soft iron or hard steel be used in an electro- (tempo- 
 rary) magnet? What would be the objection to the other? 
 
 6. The earth is a great magnet. Where are the earth's mag- 
 metic poles? 
 
 7. Distinguish between permanent magnets and electromagnets. 
 
 8. Explain what a compass is and how it works. 
 
 To increase the strength of an electromagnet, send a larger cur- 
 rent (amperes) through the turns of wire around the bar, or keep 
 the same current flowing and wind on more turns. The product 
 
 Moke ant/ 3j-eak ^ 
 
 Dry Cell 
 
 From Good's "Laboratory Projects in Physics." Used 
 by permission of the Macmillan Company, publishers 
 
 Fig. 20. — Path of electric current in operating an electric bell. 
 
 of the amperes (current) and the number of turns determine the 
 magnetizing strength of the coil. Since electromagnets are more 
 powerful than permanent magnets and since their magnetism can 
 be quickly destroyed, they have been given a great many practical 
 appUcations, such as electric bells, electric motors, electric gener- 
 ators, induction coils, telegraph, telephone, and wireless instru- 
 ments. Electromagnetic cranes are used in lifting heavy masses 
 of iron in steel mills and in the manufacture of nails, bolts, etc. 
 A large magnetic crane will lift two tons of iron at one time. 
 
THE ELECTRIC MOTOR 41 
 
 B. The Electric Bell. In the vibrating bell, when the circuit 
 is closed by pushing the button, there is an arrangement in the 
 bell which alternately closes and opens the circuit. 
 
 9. Diagram a bell, indicating the path of current by means of 
 arrows. The path of the current is not exactly the same in all 
 bells. See Practical Physics, Millikan, Gale, and Pyle. 
 
 10. What caused the tapper to move toward the bell? 
 
 11. What stops the flow of the current? 
 
 12. What causes the tapper to move away from the beU? 
 
 13. Diagram a circuit showing a battery, a push-button, and a 
 beU. 
 
 14. Diagram a battery and one push-button operating two bells. 
 The bells should be attached in parallel. 
 
 17. THE ELECTRIC MOTOR 
 
 The Constructioii and Operation of an Electric Motor 
 
 MATERIALS. St. Louis motor; two dry cells; No. 24 wire; 3S-ampere 
 battery ammeter. 
 
 One form of simple electric motor consists of two electromagnets 
 ■ — one stationary and the other so arranged that it revolves in the 
 magnetic field of the stationary coil. A device known as a com- 
 mutator reverses the direction of flow through the revolving coil 
 each half turn. The principal parts of a motor are: field magnet, 
 field coil, armature (revolving coil), commutator, and brushes. 
 
 A. Motor Operated with Permanent Field Magnet. Remove 
 the field-coil attachment from the base board and lay it aside. 
 Using the two permanent bar magnets for the field magnetism, 
 attach wires from one dry cell to the upper binding posts, causing 
 the armature to rotate. 
 
42 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 1. Name two of tKe essential parts of the motor through which 
 the current passes before it reaches the armature coil. 
 
 2. What causes the armature coil to become magnetized? 
 
 No. I. No. 2. 
 
 Motor; Bar Magnet Shunt Motor; Eleccro 
 Fields. Magnet Fields. 
 
 No. 3. 
 
 Series Motor; Electro 
 
 Magnet Fields. 
 
 No. 4. 
 The Motor may be 
 used as a generator. 
 
 From Goad's "Laboratory Projects in Physics" Used 
 hy permission of the Macmillan Company, publishers 
 
 Fig. 21. — A simple electric motor. 
 
 3. When the current is reversed through an electromagnet what 
 happens to its poles? 
 
 4. For what part of a revolution does the current flow in one 
 direction through this armature coil? 
 
THE ELECTRIC MOTOR 43 
 
 5. How many times during each revolution are the poles of 
 this armature reversed? 
 
 6. State the law which applies to the attraction and repulsion 
 of magnetic poles. 
 
 7. What should happen with regard to the direction of current 
 flow when the south pole of the armature comes nearest to the 
 north pole of the field? 
 
 8. What effect upon the direction of rotation of this motor is 
 caused by reversing the field poles? 
 
 9. Reverse the battery wires at the brush posts of the motor. 
 What effect has this upon the direction of rotation? 
 
 10. What effect upon the speed of the armature is produced by 
 turning the brush frame out of its normal position? 
 
 11. If the field poles are both north or both south (like poles), 
 what is the effect upon the rotation of the armature? 
 
 B. Motor Operated with Electromagnet for its Field. Push the 
 permanent bar magnets aside and place the electromagnet coil in 
 position to furnish the field magnetism. Connect wires so that 
 current from two dry cells passes first through the armature coil 
 and then through the field coil and back to the dry cells. This 
 represents a series-wound motor. 
 
 12. Diagram a series- wound motor. Observe the illustrations 
 and refer to text on wiring of motors or generators. 
 
 13. Connect a battery ammeter and measure the current which 
 the pressure of two dry cells sends through the motor. 
 
 14. Two dry cells in series have approximately 3 volts pressure. 
 What is the resistance of this motor in ohms? While measuring the 
 current for resistance do not let the armature rotate. Hold it. 
 Apply Ohm's Law (volts divided by ohms equal amperes). 
 
 15. This motor would be ruined if attached directly to the iio- 
 volt lines. With its resistance known, calculate by Ohm's Law 
 how many amperes would pass through it if it were attached without 
 additional resistance to the 1 10- volt hne. 
 
44 AUTOMOBILE LABORATORY MANUAL 
 
 1 6. Operate this motor with shunt wiring. Have the wiring 
 approved by the instructor. Diagram a motor wired in shunt. 
 See Practical Physics, Black and Davis. Use diagram for shunt 
 generator, omitting lamps. 
 
 i8. THE ELECTRIC GENERATOR (DYNAMO) 
 The Construction and Operation of an Electric Generator 
 
 Note. It is preferable to take the experiment dealing with the "Electric 
 Motor" preliminary to this experiment. Handle apparatus carefully. 
 
 MATERIALS. Small generator, operated by hand power (L. E. Knott 
 hand-power dissectible dynamo and motor); small lamp; battery ammeter; 
 battery voltmeter; electric bell; small motor; telephone magneto generator. 
 (Part of this apparatus must be obtained from the instructor.) 
 
 A. Explanation and Operation. In construction the simple 
 generator is a device for revolving a coil of wire between the poles 
 of a strong electromagnet. When a magnet moves into a coil or 
 away from it, a current is generated in the coil. Or if a coil 
 revolves in the presence of a magnet, a current is generated in the 
 coil. The coil cuts the lines of force produced by the magnet. 
 (The wires leading from the coil must be connected to complete a 
 circuit.) 
 
 Operate the small hand-power generator. Connect wires to it, 
 causing it to ring a bell, Hght a small lamp, and run a small motor. 
 
 1. Attach a battery voltmeter to the terminals and measure 
 its voltage at your maximum speed. 
 
 2. Attach a battery ammeter in series with a small motor, and 
 measure the amperage which passes through it at your maximum 
 speed. 
 
 3. How does varying the speed affect the voltage? As the 
 voltage increases the amperage also increases through a given 
 resistance. 
 
THE ELECTRIC GENERATOR 
 
 4S 
 
 4. Make two simple diagrams of generators showing series 
 winding and shunt winding. See Practical Physics, Black and 
 Davis. 
 
 5. If a generator armature contains a commutator, will the 
 current be direct or alternating? 
 
 From Good'i "Laboratory Projects in Physics" Used 
 by permission of the Macmillan Company, publishers 
 
 Fig. 22. — An electric generator. 
 
 6. What is the function of the field coils of an electric generator? 
 
 7. Of what material are the brushes in this small generator 
 made? in large generators and motors? 
 
 8. How does a generator get its field magnetism? Refer to 
 texts. At the begmning a very small amount of residual mag- 
 netism remains in the magnets from the last running to start the 
 voltage in the armature, which in turn starts a small current. 
 
46 AUTOMOBILE LABORATORY MANUAL 
 
 B. Telephone Magneto Generator. Operate this generator and 
 attach a small lamp. This device is sometimes used on telephone 
 instruments for the purpose of ringing up the party at the other 
 end of the line. 
 
 9. How does its field magnet differ from that of the regular 
 generator? 
 
 10. If the armature shaft contains rings in place of a com- 
 mutator, what kind of current does it deliver? 
 
 19. IGNITION SYSTEMS— A 
 
 Setting up and Operating a Simple Ignition System 
 
 MATERIALS. Four dry cells; insulated wires; vibrating induction coil; 
 metal-ring stand; automobile spark plug. (Part of the apparatus for this 
 experiment must be obtained from the instructor.) 
 
 A. The Induction Coil. An ignition system in a gas engine, 
 or an automobile, is used to produce a hot spark for igniting the 
 explosive mixture in the engine cylinder. This may be accom- 
 plished by sending a 6-volt current through an induction coil, 
 and thereby increasing the voltage to 10,000 or 15,000 volts. This 
 high-voltage current will pass through air for a short distance, 
 producing a very hot spark. 
 
 Operate a vibrating induction coil as follows: Attach a short 
 wire from one of the secondary terminals of the induction coU to 
 within \ inch of the other secondary terminal, but not touching it. 
 This j-inch opening will form the spark gap. An induction coil 
 should not be operated with the spark gap too wide, as this may 
 puncture the insulation of the secondary coil and ruin it. Connect 
 four dry cells in series. {Caution. The current from the secondary 
 terminals of an induction coil is dangerous. Keep away from the 
 secondary wires when the latteries are attached.) Attach one wire 
 from the dry cells to one of the primary terminals of the indue- 
 
IGNITION SYSTEMS 
 
 47 
 
 tibn coil. Touch the other wire from the dry cells to the other 
 primary terminal of the induction coil. A spark should jump 
 across the spark gap of the secondary terminals. Do not handle 
 the induction coil without first disconnecting the dry cells. 
 
 1. Diagram an induction coil. See Fig. 33. 
 
 2. Should the current which passes through the primary 
 
 ,.£r\jO^ 
 
 X)ry Ce//s 
 A 
 
 Touch this 
 io the second 
 primary /ermina/. 
 
 Spark 
 
 fnduct/on Coi7 
 
 Spar/r P/u^ 
 
 Dry CeHs 
 
 From Good's "Laboratory Projects in Physics." Used 
 by permission of the Macmillan Company, publishers 
 
 Fig. 23. — Simple ignition system containing primary and secondary ciraiits. 
 
 winding of this type of coil be a continuous flow or an inter- 
 mittent flow? 
 
 3. Explain the purpose of the vibrator. If the vibrator does 
 not operate, it may need some adjustment. Consult the instructor. 
 
 4. What pulls the vibrator toward the coil? What draws it 
 back? 
 
 5. What is a condenser made of? What is its function? In 
 
48 AUTOMOBILE LABORATORY MANUAL 
 
 automobile ignition systems, the timer usually serves the purpose 
 of the vibrator and the induction coil does not contain a vibrator. 
 
 B. The Secondary Circuit — Spark Plug. Disconnect the bat- 
 teries, temporarily, from the induction coil. Remove the wire from 
 the secondary terminals. Fasten an automobile spark plug to the 
 clamp of the ring stand. Connect a weU-insulated wire from one 
 secondary terminal of the induction coU to the spark plug. Con- 
 nect a second wire from the other secondary terminal to any metal 
 part of the ring stand. Operate the induction coil as before and 
 the secondary current should jump across the spark gap of the 
 spark plug. 
 
 6. Diagram a sectional view of a spark plug and tell of what 
 materials it is made. See The Gasoline Automobile, Motor Vehicles. 
 
 7. The secondary circuit is grounded through the ring stand. 
 What is meant by the term " grounded circuit " ? 
 
 C. Reference Work. 
 
 8. What is meant by the expressions " high-tension current " 
 and " low-tension current " ? 
 
 9. What should be the width of the spark gap on a spark plug? 
 
 10. Name two kinds of batteries that may be used for producing 
 current for ignition purposes. 
 
 11. What are two common classes of magnetos? 
 
 12. How can the spark plug of an automobile be tested to insure 
 that it sparks? 
 
 (13. State three possible causes of trouble in the electric circuits. 
 
IGNITION SYSTEMS 49 
 
 20. IGNITION SYSTEMS— B 
 
 Operation of Automobile Ignition Systems 
 
 MATERIALS. Four dry cells; vibrating induction coil; four metal-ring 
 stands; four spark plugs; wooden block with four binding posts; non- vibrating 
 induction coU (make-and-break coil). (Part of the apparatus for this experi- 
 ment must be obtained from the instructor.) 
 
 A. Automobile Ignition System. Attach four spark plugs to 
 four ring stands. Connect the four stands by means of a wire, 
 and extend this wire to one terminal of the induction coil. From 
 the four spark plugs lead four well-insulated wires to four binding- 
 posts placed near the corners of a square wooden block. Attach 
 a well-insulated wire to the second terminal of the vibrating induc- 
 tion coil. Insulate this wire by puUing a piece of rubber tubing 
 over it. {Caution. The secondary current is dangerous. Keep 
 away from the secondary wires when the batteries are attached) 
 When this wire is placed in contact with any one of the posts on 
 the wooden block, you should get a spark at the spark plug which 
 that post controls. This block with the four posts represents the 
 " distributor " of a four-cylinder automobile ignition system. 
 
 The closing of the battery circuit (primary circuit) by touching 
 one wire to one of the primary terminals of the induction coil 
 represents the " timer " of an automobile ignition system. 
 
 Automobiles, as a rule, do not have vibrating coils. The timer 
 makes and breaks the primary circuit, serving the purposes of the 
 vibrator. The Ford ignition system is an exception. The Ford 
 car is provided with four vibrating coils, one for each cylinder. 
 
 In many of the common types of cars the low-voltage current 
 supply for operating the induction coil is taken from the storage 
 battery. 
 
 I. Diagram the apparatus used above, showing dry cells, 
 induction coil, spark plugs, and distributor. 
 
so 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 2. State the two possible sequences of firing for four-cylinder 
 engines. See Motor Vehicles. 
 
 3. What is the purpose of the ignition switch on the instrument 
 board of an automobile? 
 
 4. What is the purpose of the distributor? 
 
 S(§M t=i5<§« ^S©< t=S^ i=» 
 
 Jfedvy rubber- 
 fubin^ for 
 /nsu/at/on. 
 
 T/me^ — make , 
 ,(ouch contacf /lere. 
 
 From Good's *' Laboratory Projects in Physics." Used 
 by permission oj the Macmitlan Company, publishers 
 
 Fig. 24. — ^Ignition system, illustrating the operation of the timer and the distributor 
 of an automobile. 
 
 B. Make-and-break Ignition. Some gas engines are operated 
 by a "make-and-break" spark (wipe spark). Connect up four 
 dry cells. Connect a wire from one terminal of the battery to a 
 simple " make-and-break " coil. This device consists of a coU of 
 wire wound around an iron core. Slip a heavy rubber tube over the 
 second wire from the battery for insulation. Touch the second 
 terminal of the make-and-break coil with the second wire from the 
 battery, and pull it quickly away. Use one hand only, to avoid a 
 shock. A hot spark will occur at the time of break, due to the self- 
 induced voltage in the coil. If this make-and-break occurs in the 
 cylinder of an engine, the spark may be used for ignition. 
 
STORAGE BATTERY 51 
 
 5. Diagram a make-and-break ignition system. See The 
 Gasoline Automobile. 
 
 C. Magneto Generators. Magnetos are sometimes employed 
 as sources of current for ignition. These generators take the place 
 of the battery. They are either of the high-tension or the low- 
 tension types. The low-tension magneto requires a separate induc- 
 tion coil. The ' high-tension magneto is constructed with the 
 induction coil in the magneto. 
 
 D. Reference Work. The Gasoline Automobile. 
 
 6. Make a diagram showing the main parts of a typical ignition 
 system, including induction coil and distributor. 
 
 7. State at least five possible causes of failure of an ignition 
 system to produce a spark. 
 
 21. STORAGE BATTERY— A 
 The Construction and Operation of a Simple Lead-storage Cell 
 
 MATERIALS. Simple storage cell; dilute solution of common salt; 
 battery voltmeter: electric bell; 2-volt lamp; small 2-volt motor; lamp 
 board and i-ampere lamp; iio-volt or lower voltage direct current. 
 
 Caution. Sulphuric acid "will destroy clothing and cause burns. Handle with 
 extreme care. 
 
 A. Make a simple storage cell by filling a battery jar three- 
 fourths full of a 20 per cent solution of sulphuric acid. Suspend 
 in it two plates of ordinary sheet lead by folding the lead plates 
 over the edges of the jar. With a i-ampere lamp as rheostat, prepare 
 to send a i lo-volt direct current through the cell or to send a direct 
 current from a small generator. (Caution. Do not connect the 
 cell directly to the line wires without resistance, as this would blow 
 out the fuse.) Test the charging current with a salt solution 
 (a quarter teaspoonful in a tumblerful of water) to find which 
 
52 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 terminal is negative. In making this test attach the lamp in 
 series with one wire to insure against a short circuit if the wires 
 should accidently touch in the salt solution. The negative terminal 
 gives off more bubbles. Connect the brown-coated plate (positive) 
 to the positive terminal of the line. In charging, connect positive 
 to positive and negative to negative. 
 
 Ouf/ei for I/O SfoU d/i~ec'f current 
 
 ^ 
 
 Pos/t/ve. 
 p/3te 
 
 p/ate 
 
 One Ampere /amp 
 rests fsnce. 
 
 Jar iv/t/) /eac/ p/ates 
 and su/fuh/c 
 
 From Good's "Laboratory Projects in Physics." Used 
 by permission of the Macmillan Company, publishers 
 
 Fig. 25. — Wiring scheme for charging a simple storage battery. 
 
 The charging current should pass through the cell from positive to 
 negative. Hydrogen is set free at the negative plate and oxygen 
 at the positive (electrolysis). The oxygen, instead of escaping 
 into the air, attacks the lead, formmg a brown coat of lead peroxide, 
 Pb02. When the cell is charged, the positive plate is coated with 
 lead peroxide and the negative plate of pure lead act like the 
 positive and negative plates of any simple liquid cell. 
 
STORAGE BATTERY 
 
 S3 
 
 Allow the current to pass through this cell for fifteen minutes 
 (Read Black and Davis on the storage battery.) Disconnect from 
 the charging lines and test the pressure with a voltmeter. {Caution. 
 Do not connect an ammeter to a storage battery without some resistance 
 such as a motor or a lamp in series with the meter, as this might ruin 
 both the ammeter and the battery.) 
 
 Outfet for I/O voU direct currenf 
 
 One Ampere /amp 
 res/s/3nce . 
 
 r| Water containing 
 o few yrs/77a of 
 co/77mon sa/t^ 
 Sodium C/i/or/de. 
 
 From Good's "Laboratory Projects in Physics." Used 
 by permission of the Uacmillan Company, publishers 
 
 Fig. 26. — Apparatus for determining which terminal of a supply line is positive. 
 
 1. What is the voltage of a lead-storage cell? See texts. 
 
 2. Ring an electric bell. Make a diagram of the apparatus with 
 parts labeled. 
 
 3 Operate a small motor and measure the amperage. 
 4. What happens to a storage battery if the wires are connected 
 without resistance (some suitable lamp or motor)? 
 
 B. Chemical Reaction. Disregarding intermediate steps in the 
 chemical reaction, we may represent the operation as follows: 
 
54 AUTOMOBILE LABORATORY MANUAL 
 
 Charged Condition Discharged Condition 
 
 Pos. Elec- Neg. Pos. Elec- Neg. 
 
 Plate trolyte Plate Plate trolyte Plate 
 
 Pb02 + aHsSOi + Pb <=4 PbSOi + 2H.2O + PbSOi 
 
 The reaction goes in the opposite direction when a current is 
 reversed through the cell in the operation of charging it. The cell 
 does not store up electricity. The energy of the charging current 
 is used in the formation of lead peroxide on the positive plate. 
 When the charging current stops, the two plates, on account of 
 their different chemical nature, act like a simple liquid cell, which, 
 on account of the chemical difference between the two plates, is 
 capable of producing a reaction with the electrolyte and generating 
 a current. The hydrogen ions of the sulphuric acid unite with the 
 oxygen of the lead peroxide, forming water, and SO4 ions go to 
 produce lead sulphate on both plates. Thus on full charge the 
 sulphuric acid is concentrated and on discharge it is dilute. The 
 specific gravity is, therefore, a fairly good test of the charged or 
 discharged condition of the cell. The electrolyte, however, must 
 be kept full by the addition of distilled water, since evaporation 
 reduces it. 
 
 Reference Work. Practical Physics, Black and Davis. 
 
 5. When a storage battery is discharged what chemical com- 
 pound covers the plates? 
 
 6. What are some disadvantages of a lead storage battery? 
 
 7. What efficiency is obtained from a battery in good condition? 
 
 8. Mention three uses for storage batteries. 
 
 9. In the Edison storage battery what are the plates composed 
 of and what electrolyte is used? 
 
AUTOMOBILE ELECTRIC CIRCUITS SS 
 
 22. AUTOMOBILE ELECTRIC CIRCUITS— A 
 Storage-battery Charging and Ignition Circuits 
 
 Note. The experiments, Ignition Systems — A and Ignition Systems — B 
 should precede this experiment. 
 
 MATERIALS. Automobile with storage battery, ignition, starting and 
 lighting circuits. 
 
 A. The Charging Circuit. The generator is used for charging 
 the storage battery. The current which it produces passes through 
 the ammeter, thus indicating at all times the amount of charging 
 current which the storage battery receives. 
 
 1. By means of the wires, beginning at the generator, trace the 
 circuit which carries current through the storage battery, including 
 the ammeter on the instrument board. 
 
 2. Make a simple wiring diagram showing the positions of 
 generator, ammeter, and storage battery. Have this work 
 approved by the instructor. 
 
 B. The Ignition Circuit — A. In starting the engine the ignition 
 current in many cars is supplied by the storage battery. This cur- 
 rent is carried to the timer and the induction coil which produces a 
 high-tension current for operating the spark plugs. The tiiner is a 
 device for making and breaking the primary circuit of the induction 
 coil comparable in effect to the vibrator on a vibrating coil. It 
 serves to make and break the flow of current through the primary 
 coil of the induction coil. These pulses induce a high- voltage cur- 
 rent in the secondary coil which is connected to the spark plugs. 
 
 3. By means of the wires trace and record the battery ignition 
 circuit, beginning with the positive side of the "storage battery, 
 including the ammeter, the ignition switch, the timer, and the 
 primary circuit of the induction coil. 
 
S6 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 N^ 
 
 
AUTOMOBILE ELECTRIC CIRCUITS 57 
 
 4. Make a simple wiring diagram of a battery ignition circuit 
 showing the positions of the above parts. See diagrams in The 
 Gasoline Automobile, chapter on Battery Ignition Systems. 
 
 The secondary circuit of the induction coil leads back to the 
 distributor. Here the high-tension current is sent out to each 
 spark plug at the proper time for the explosion. Note that the 
 secondary circuit of the induction coil is represented by only one 
 heavily insulated wire. Instead of a return wire from the outside 
 of the plug to the induction coil the metal of the car serves to 
 bring this current back. This is known as a grounded circuit. 
 
 5. In the ignition circuit what is the function of the ignition 
 switch located on the instrument board? 
 
 6. What is the function of the induction coil? 
 
 7. Diagram a timer mechanism, showing contact arm, cam, 
 condenser, and breaker points. 
 
 8. Explain the purpose of each of these parts of the timer. See 
 The Gasoline Automobile. 
 
58 AUTOMOBILE LABORATORY MANUAL 
 
 23. AUTOMOBILE ELECTRIC CIRCUITS— B 
 Storage Battery Ignition, Lighting, and Starting Circuits 
 
 A. Ignition Circuit. Ignition Current from the Generator. 
 When the car is running faster than 8 or 10 miles an hour the 
 generator delivers a current with voltage greater than that of the 
 storage battery. This overcomes the battery pressure and forces 
 current back into the storage battery charging it. At the same 
 time, at speeds above 8 or 10 miles per hour, the generator supplies 
 part of its current to the induction coil for ignition. 
 
 Note that the wiring scheme makes this possible. Accordingly, 
 when the engine attains the proper speed, the ammeter no longer 
 indicates that the storage battery is discharging, but the indicator 
 moves over to the charging side, showing that current is flowing 
 through the instrument in the opposite direction. 
 
 Beginning at the generator, by means of the wires trace the path 
 of current which the generator supplies for operating the primary 
 circuit of the induction coil. This circuit should include generator, 
 ignition switch, timer, and primary of the induction coil. * 
 
 1. Make a wiring diagram showing the relative positions of 
 the different units of this circuit. Include, also, the ammeter and 
 the storage battery in relation to the generator ignition circuit. 
 
 2. Does current in this generator ignition circuit flow through 
 the ammeter? 
 
 B. Lighting Circuits. Assume that lighting current is obtained 
 from the storage battery. This circuit is carried to the lighting 
 switch on the instrument board from which point it is distributed 
 to the lighting circuits. 
 
 3. Beginning at the storage battery trace the wiring to the 
 
AUTOMOBILE ELECTRIC CIRCUITS 59 
 
 lighting switch on the instrument board and return to the storage 
 battery. Make a diagram with proper instruments included. 
 
 4. Beginning at the lighting switch, diagram a wiring scheme 
 which represents the headlight circuit when the lamps are operated 
 " bright " (lamps in parallel). 
 
 5. Diagram a headlight wiring circuit from the lighting switch 
 when the lamps are lighted " dim " (lamps in series). 
 
 6. What is the voltage of the storage battery? (Each lead cell 
 gives approximately two volts.) 
 
 7. When does more current flow through the lamps, in series 
 or in parallel? 
 
 8. Which have the greater resistance, two lamps in series or 
 two lamps in parallel? 
 
 9. What voltage lamps are used in the headlights? What 
 would be the effects if lamps of double this voltage or half this 
 voltage were used? 
 
 10. If one headhght burns out, can the other one be operated, — • 
 (a) " dun "? (6) " bright " ? Explain. 
 
 11. Diagram the circuit which operates the instrument board 
 light; and the tail light. 
 
 1 2 . What is the voltage of each of these lights? 
 
 13. Why are they connected in series? 
 
 C. The Electric Starting System. 
 
 14. Diagram the starting circuit with necessary parts repre- 
 sented. 
 
 15. Why are the wires which lead from the battery to the starting 
 motor very heavy? With a 6-volt battery about what amperage 
 is required to operate a starting motor? 
 
6o 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 24. ENGINE COOLING SYSTEMS— B 
 
 Pump Systems, the Franklin Air-Cooled System, Troubles and 
 
 Repairs 
 
 MATERIALS. Automobile chassis, reference books. 
 
 A. Pump System of Cooling. A more positive means of circu- 
 lation in the cooling system is obtained in many of the higher- 
 priced cars by using a pump in the circulating system. 
 
 I. Which system — ^pump or thermo-siphon — is more likely to 
 permit the water surrounding the cylinders to become (a) too hot? 
 {b) too cold? 
 
 Fig. 28. — Pump system. 
 
 2. What type of pump is most common in pump systems of 
 circulation? 
 
 3. Does a pump-feed system usually have smaller or larger 
 pipes than a thermo-siphon system? Why? 
 
 4. Explain the fact that an engine works more efficiently when 
 the temperature of the water in the water jacket is above 160° F. 
 
 5. What is the function of a thermostatic valve on a water- 
 cooling system? Name one make of car that is equipped with a 
 thermostatic valve. 
 
ENGINE COOLING SYSTEMS 
 
 6i 
 
 B. The Franklin Air-cooling System. 
 
 6. Describe briefly the Franklin cooling system. 
 Gasoline Automobile. 
 
 See The 
 
 C. Anti-freezing Mixtures. 
 
 7. List the characteristics of an ideal anti-freezing compound. 
 Does any specific mixture or solution possess all of these character- 
 istics? See The Gasoline Automobile. 
 
 8. Explain the method of making up anti-freezing mixtures to 
 withstand a temperature of zero F. from (a) calciimi chloride; 
 (6) denatured alcohol; (c) alcohol and glycerine solutions. 
 
 TbermostBtlc 
 Talve 
 
 Pump system with thermostatic valve. 
 
 D. Troubles and Remedies. 
 
 9. Name three possible causes for water boiling in a cooling 
 system. If the water boils, stop the engine immediately and iind 
 the cause. 
 
 10. How may sediment be removed from a cooling system? 
 See The Gasoline Automobile, Cooling Troubles. 
 
 1 1 . How may the water be kept at the efficient operating tem- 
 perature in winter weather? 
 
 A radiator may feel warm at the top and be freezing below. If 
 the tubes are frozen at the bottom, the radiator should be covered 
 with a blanket and the engine should be run slowly until the tubes 
 thaw out. 
 
62 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 Leaky radiators may sometimes be repaired temporarily with 
 such substances as seaUng wax, tire putty and plaster of Paris. 
 
 25. ENGINE-OILING SYSTEMS— B 
 
 Types of Oiling Systems, Troubles, and Adjustments 
 
 MATERIALS. Automobile chassis and reference books. 
 
 The cylinders of the automobile power plant are the most 
 difficult parts of the mechanism to lubricate on account of their 
 location, variations in speed, and the great heat generated by the 
 
 Eccentric for 
 Opsrafing Oil Pump, 
 
 Time^ 
 Qears 
 
 Crcnk shaft FrvntEnd 
 Beari'r7a 
 
 ^Oii Pump 
 
 Fig. 30. — Splash system of oiling with circulating pump. 
 
 explosion of the gas. There is a possibility of excessive or insuf- 
 ficient oiling as well as a possibiHty of a lack of uniformity of oil 
 distribution to the different cylinders. In order to provide proper 
 lubrication under varying conditions a number of special oihng 
 systems are in common use. 
 
 A. Types of Oiling Systems. 
 
 I. Name three types of splash systems. See Dyke. How do 
 they differ? 
 
ENGINE-OILING SYSTEMS 63 
 
 2. What kind of lubrication system does the laboratory engine 
 have? Describe it. 
 
 3. Name five makes of car which have circulating splash oOing 
 systems. See Dyke, Specifications of Leading Cars. 
 
 4. Under what conditions of operation of an automobile on the 
 road is uniformity of oil distribution difficult to maintain? See 
 Dyke. 
 
 5. What system of lubrication is unaffected by the above con- 
 ditions of operation? 
 
 6. Does the presence of an oil indicator on the dash of an 
 automobile necessarily mean that the oiling system used is a 
 " force-feed " system? What kind of system might it be? 
 
 7. Describe briefly the operation of the " full-force-feed " 
 system of lubrication. Name one make of car which uses this 
 system. See Dyke. 
 
 B. Troubles and Adjustments. 
 
 8. What trouble might occur in a " force-feed " system, 
 causing it to fail to operate? What harm would result thereby? 
 
 9. Of what practical use is an oil-pressure gauge? Would an 
 excessive oil pressure mean that the engine is getting too much oil? 
 
 10. What trouble may result (a) if an engine is not getting 
 enough oil? {b) if it gets too much oil? 
 
 11. State the probable cause of an excessive amount of oil in 
 the combustion chamber. Are old or new cylinders and pistons 
 hkely to have this trouble? 
 
 12. What is probably the cause if the exhaust smoke is (a) white 
 or blue, (i) black? 
 
 13. What kind of engine oil should be used in an air-cooled 
 engine or in an engine with loose pistons and rings? 
 
64 AUTOMOBILE LABORATORY MANUAL 
 
 26. LUBRICATION— TRANSMISSION AND CHASSIS 
 
 MATERIALS. Automobile chassis and reference books. Use the instruc- 
 tion book for the car with lubrication chart and refer to te.xtbooks. 
 
 A. The Clutch. Some clutches are constructed to operate in 
 oil, others to run dry. Cone clutches usually run dry. 
 
 1. What kind of lubricant causes wet clutches to slip? How 
 can this trouble be remedied? See The Gasoline Automobile. 
 
 B. The Change Gears. 
 
 2. Should the lubricant be stiff grease or heavy fluid grease? 
 Why? See The Gasoline Automobile. 
 
 3. How frequently should the gear box be cleaned out and 
 refilled with new lubricant? 
 
 4. Parts of the gears in the form of chips sometimes break off 
 and fall to the bottom of the gear case. What damage might 
 result from using a very stiff grease instead of a semi-fluid grease? 
 
 5. How deep should the oil stand in the transmission case? See 
 Instruction Book. 
 
 C. The Universal Joint. 
 
 6. Describe the provision for lubrication and state the type of 
 lubricant used. 
 
 D. The Differential and the Rear Axle. 
 
 7. Why are semi-solid oils commonly used in the rear-axle 
 housing. See The Gasoline Automobile. 
 
 8. Examine the rear axle of the Ford. State (a) the kind of oil 
 required, (6) the amount, (c) how it is put in. 
 
 9. Examine the rear axle of one larger automobile. State 
 (a) kind of oil required, (J) the amount, (c) what provisions are 
 made for taking out old oil and replacing it with new. 
 
 10. How frequently should wheel bearings and the differential 
 
FRONT AXLES 65 
 
 be repacked with oil? If a differential chips or is badly worn, 
 small pieces of steel may lodge in the oil. 
 
 11. What prevents grease from working out and water and sand 
 from working into the rear-axle housing? 
 
 12. If old oil is not removed from a rear-axle housing before 
 adding new oil, what effect does continued use have updn the old 
 oU? 
 
 D. Chassis. See Instruction Book. 
 
 13. What parts on the front axle require lubrication? 
 
 14. How are the front wheels suppUed with oil? 
 
 15. What parts of the control system require oil? 
 
 16. Why do springs need lubrication? How are they lubri- 
 cated? See The Gasoline Automobile. 
 
 27. FRONT AXLES 
 Axles, Steering Adjustments, and Alignment of Wheels 
 
 MATERIALS. Automobile chassis; ball of cord; rule; reference books. 
 
 In order to insure safety the front-axle assembly and steering 
 mechanism should be inspected frequently and adjusted when 
 necessary. It is the function of the steering knuckle and the 
 wheel bearings to carry the entire weight of the front of the car 
 and to withstand hard knocks and strains. These parts, there- 
 fore, should be kept well lubricated to prevent excessive wear. 
 
 Jack up the front wheels for making a study of this mechanism. 
 
 A. The Steering Mechanism. 
 
 1. Explain the operation of the steering knuckle. 
 
 2. Shake front wheels vigorously. If they give evidence of 
 play or lost motion due to wear, at what points is this wear likely 
 to be found? 
 
66 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 3.'*' What is the name of the rod which connects the two steering 
 knuckles? 
 
 
 '■i- 
 
 S- 
 
 ij| 
 
 
 S'i: 
 
 
 
 fc^ 
 
 V 
 
 
 ^^ ^ 
 
 
 
 
 
 ^ 
 
 
 ^ 
 
 5 
 
 1 
 
 
 \ 
 
 
 
 1 
 
 Q 
 
 iJl 
 
 ilk. 
 
 1 
 
 / 
 
 V 
 
 ^ 
 
 
 A' 
 
 kJ 
 
 k 
 
 
 
 . 
 
 k 
 
 
 
 -^ 
 
 '•J 
 
 4. If this rod should break when the car is in operation, what 
 would the wheels do? 
 
 5. What is the function of (a) the steering-knuckle pin, (6) the 
 
FRONT AXLES 67 
 
 Steering yoke, (c) the spindle, (e) the retention nut, (/) roller 
 bearings? 
 
 B. Wheel Alignment. Place a chair behind one rear wheel 
 and another chair in front of the front wheel on the same side of 
 the car. Tie the end of a long piece of cord to the chair at the 
 rear at a point just above the rear hub. Stretch the string to the 
 chair in front of the front wheel and tie it at a point so that it 
 stretches tight just above the front hub. Move the chairs so that 
 the string just barely touches the sides of the rear wheel. Turn 
 the front wheel so that the string just barely touches the sides 
 of the front wheel. Now go to the opposite side of the car and 
 sight along the line of the front and rear wheels. 
 
 6. On the opposite side does the front wheel stand in the^ame 
 direction as the rear wheel? How does it stand? 
 
 7. What is this adjustment of the front wheels called? See 
 The Gasoline Automobile — Alignment of Wheels. 
 
 8. How much should the two wheels vary from the parallel 
 position? 
 
 Without changing the position of the front wheels move the 
 chairs and the string to the opposite side of the car. Again move 
 the string gently till it just barely touches the sides of the rear 
 wheel and the front wheel just above the hub. Now measure how 
 far the front edge of the front wheel is from the string. 
 
 9. How much do these wheels " toe in " or " gather " ? (The 
 wheels should run true if this method is used.) 
 
 10. If the gather is incorrect take two wrenches and reset the 
 adjustable yoke at the one end of the tie rod. Adjust the wheels so 
 that the gather is correct. If the gather is correct at the beginning, 
 set it so that it is incorrect by one-half inch. Make certain to 
 replace all cotter pins. Have this work approved by the instructor. 
 On the report sheet describe your procedure. 
 
 11. Describe another method of measuring "toe in." See 
 Dyke. 
 
68 AUTOMOBILE LABORATORY MANUAL 
 
 12. What is the reason for setting wheels with " toe in " or 
 "gather"? 
 
 13. What is meant by " camber " ? 
 
 14. How much camber is commonly given to wheels? 
 
 15. Explain why wheels are cambered. 
 
 28. REAR AXLES 
 
 MATERIALS. Demonstration Ford rear axle mounted on a wooden stand 
 in the laboratory. 
 
 Remove the nuts which hold the two halves of the differential 
 housing of the Ford rear axle and examine the differential mechan- 
 ism and the axle shaft. Follow instructions given in the Ford 
 Manual and in The Model T Ford Car. Examine illustrations in 
 the Ford Manual. 
 
 A. The Ford Rear Axle. 
 
 I . Is the Ford axle a live axle or a dead axle? See The Gasoline 
 Auiomobile. 
 
 2. Is this a simple, semi-floating, three-quarter-floating, or full- 
 floating rear axle? Explain. 
 
 3. How many roUer bearings has the Ford rear axle? Where 
 are they located? See Fig. 71. 
 
 4. Which of the roller bearings carry the weight of the car? 
 
 5. What kind of bearings in the differential housing carry the 
 end of the drive shaft? 
 
 6. What do the others carry? 
 
 7. What is the function of the radius rods? If one radius rod 
 is bent how is the rear axle affected? 
 
 8. To what is the rear wheel attached? How is this attach- 
 ment made? 
 
 9. To what is the castle or retention nut attached? 
 10. What does the drive-shaft pinion operate? 
 
REAR AXLES 
 
 69 
 
 II. State the function of {a) the axle housing cap, (6) a thrust 
 washer. 
 
 12. How is the Ford rear axle lubricated and what kind of 
 lubrication is used? 
 
70 AUTOMOBILE LABORATORY MANUAL 
 
 B. Rear Axles, — Other Types. 
 
 13. Examine an illustration of a full-floating rear axle. See 
 Motor Vehicles. In this type of construction does the weight rest 
 upon the axle shaft as in the Ford or upon the axle housing? 
 
 14. In tht full-floating rear axle how is the power for driving the 
 rear wheel transmitted from the axle shaft to the wheel? 
 
 15. Examine an illustration of the three-quarter-floating type of 
 rear axle. How does this construction differ from the full-floating 
 type? 
 
 16. Examine an illustration of the semi-floating type. What 
 supports the weight of the machine in this type? 
 
 17. To what is the hub fastened in the semi-floating type? 
 
 29. VALVE MECHANISMS— A 
 Removing a Valve, Its Characteristics and Function 
 
 MATERIALS. Ford engine; valve spring compressor; valve spring tools. 
 
 The operation of the automobile engine requires two valves — one 
 for letting the mixture into the cylinder during the intake stroke; 
 the other for letting the burned gases pass out into the exhaust 
 manifold after the completion of the firing stroke. 
 
 The most common type of valve is the " poppet valve " or 
 mushroom-shaped valve. Its main parts are: head, valve face, 
 and stem. It must be so adjusted that it opens and closes precisely 
 at the proper time, and, when it is shut, it must close perfectly 
 tight. If the " valve face " or the " valve seat " becomes worn, 
 pitted, or warped, the engine will leak gas on the compression and 
 on the firing stroke with a corresponding loss of power. The main 
 causes of loss of compression are piston leak and valve leak. 
 See Fig. 10. 
 
 I. Remove a valve from the Ford engine as foUows: With a 
 valve-spring compressor raise the valve-spring retainer or washer 
 
VALVE MECHANISMS 71 
 
 and with a pair of pliers remove the valve-seat pin. Place the pin 
 on the table so that it will not be lost. Now pull this valve out 
 through the valve-stem guide. Remove also the valve spring and 
 retainer. Have this work approved by the instructor, then 
 replace the valve, taking care to properly set the valve-seat pin. 
 Make a sketch of a poppet valve, showing valve head, valve face, 
 valve seat, and valve stem. See Dyke. 
 
 2. In the operation of a valve state the function of the follow- 
 ing parts: the valve spring, the valve lifter, the valve-stem guide, 
 the cam, the cam ears. 
 
 3. In a T-head engine how are the valves located with respect 
 to the position of the cylinder? 
 
 4. State the position of inlet and exhaust valves during each 
 stroke of a four-stroke engine. 
 
 5. In what direction does the engine piston move when the 
 inlet valve is open? When the exhaust valve is open? 
 
 6. What is a valve cap and what is its purpose? 
 
 7. Distinguish between side valves and overhead valves. 
 
 8. Why is it necessary to have clearance between the valve stem 
 and the valve lifter? 
 
 9. What amount of clearance is commonly provided? 
 
 10. How does heating of the valves and valve stem affect 
 clearance? 
 
 11. When clearance is measured what should be the position 
 of the cam? 
 
 1 2 . When clearance is measured should the engine be cold or hot? 
 
 13. Name two special types of valves other than the common 
 poppet valve. 
 
72 AUTOMOBILE LABORATORY MANUAL 
 
 30. VALVE MECHANISMS— B 
 
 Valve Adjustments and Valve Grinding 
 
 MATERIALS. Automobile, any standard make; valve push-rod with 
 adjustment screw; valve grinding tools. 
 
 A. Valve Adjustments. See Dyke. Measure the valve clear- 
 ance on the laboratory automobile, using two thicknesses of 
 ordinary writing paper as a gauge. 
 
 1. Why is it necessary to adjust occasionally the clearance of 
 valves? 
 
 2. What is the average lift of the valves of an automobile? 
 
 3. If valve clearance is too great how is the operation affected? 
 
 4. On many automobiles the valve lifter contains two nuts — 
 the upper one is the head of the adjustment screw and the lower 
 one is a lock nut. Examine these nuts on the automobile. Explain 
 how the adjustment is made. Inquire of the instructor. 
 
 5. What trouble sometimes results in using old valve springs? 
 
 B. Valve Grinding and Reseating. See Dyke. 
 
 6. What materials are needed for grinding valves? 
 
 7. State the steps in the procedure of preparing to grind valves. 
 
 8. How can you determine when a valve is properly ground or 
 when it seats properly? 
 
 g. Under what conditions do valves need reseating or reaming? 
 
 10. Is loss of compression a certain indication that valves need 
 grinding? Explain. 
 
 1 1 . How can you determine whether or not a valve needs grind- 
 ing? 
 
 12. Which valve is more likely to need grinding? Why? 
 
 13. What test can be made to determine whether valves leak? 
 
INDUCTION COILS 
 
 73 
 
 C. Miscellaneous. 
 
 14. Why is it sometimes necessary to replace valve-stem guides? 
 
 15. State procedure in making a test for locating noise due to 
 improper valve adjustment. 
 
 16. What troubles may be caused by weak valve springs? 
 
 17. Which valves are more likely to become worn — inlet or 
 exhaust? Why? 
 
 31. IGNITION INDUCTION COILS 
 
 MATERIALS. Vibrating induction coil; make-and-break induction coil; 
 automobile induction coil; wires; five dry cells. 
 
 A. Vibrating Induction Coil. Connect four dry cells in series 
 and attach one terminal of this dry-cell battery to one of the 
 
 Prima 
 
 Terminals^ 
 ^ Ptimai^ Circuit 
 
 tSeconc^a/^ 
 
 Battery 
 Fig. 33. — Essential parts of a vibrating induction coil. 
 
 primary binding posts of the vibrating induction coil. Attach a 
 short wire to one of the secondary binding posts of the induction 
 coil and bend it so that the other end will stand about \ inch from 
 the other secondary binding post. (Caution. Do not operate an 
 induction coil without this wire between the secondary terminals as a 
 protection against short-circuiting when the primary circuit is closed.) 
 
74 AUTOMOBILE LABORATORY MANUAL 
 
 Now touch the other terminal of the battery to the other primary 
 binding post and notice that hot sparks jump across the spark 
 gap. Note the action of the vibrator. For a description and 
 diagrams of the vibrating induction coil see Practical Physics, 
 MiLLikan, Gale, and Pyle. 
 
 1. Compare the two coils of wire with regard to (a) number 
 of turns, (b) thickness of wire. 
 
 2. Diagram the wiring circuits of an induction coil including 
 the vibrator and the condenser. See MiUikan, Gale, and Pyle. 
 
 3. When a current is passed through the primary coil of the 
 induction coil, what effect is produced upon the soft iron core? 
 
 4. Does this effect continue when the current stops flowing? 
 
 5. What causes the vibrator to move toward the iron core? 
 
 6. What causes the vibrator to move away from the iron core? 
 
 7. Where are the contact points of an induction coil located? 
 
 8. What important part of the induction coil is connected 
 between the contact points? 
 
 9. How does a condenser reduce the spark at the contact points 
 of the vibrator? 
 
 10. What effect has this upon the suddenness with which the 
 current is broken in the primary circuit? 
 
 1 1 . How does this affect the magnetism surrounding the primary 
 coil? 
 
 When a magnetic field is being built up or is being removed from 
 a coil of wire a current of electricity is induced in the coil of wire. 
 The greater the number of turns, the greater the voltage of the 
 induced current. The voltage in the secondary is greater if the 
 change in the magnetic field takes place more quickly. 
 
 12. Why is an intermittent current used in the primary of an 
 induction coil? 
 
 13. What is the purpose of the adjustment screw at the vibrator? 
 
 14. Beginning at the battery trace the primary circuit by naming 
 the parts through which the current passes. 
 
INDUCTION COILS 
 
 75 
 
 15. What automobile makes use of vibrating induction coils for 
 ignition? 
 
 16. How can short-circuiting within the coil be prevented? 
 See The Gasoline Automobile. 
 
 B. Simple Make-and-break Induction Coil. The simple make- 
 and-break induction coil is sometimes used for ignition purposes in 
 
 / Yi'Kv W '^ *^ V V V V//i','> * 
 V\ V--^ -~ - »— - :: - --^ - - -^ /' ,' 
 
 r!Sig-S-'7s»^-4-''T5sS. 
 
 ~.-M/. 
 
 Spark 
 
 Battery 
 
 Fig. 34. — Simple make-and-break spark coil sometimes used on gas engines. 
 
 small gasoline engines. Connect four dry cells in series. Attach 
 an insulated wire to one terminal of this battery and brush the other 
 end of the wire quickly over the other terminal of the battery. 
 Notice the spark which follows across the gap when the circuit is 
 broken. Attach a wire from one terminal of the battery to one 
 of the primary terminals of the simple make-and-break induction 
 coil. Attach another wire to the other terminal of the coil and 
 
76 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 brush the free end as before over the other terminal of the battery. 
 Again observe the spark across the gap. This illustrates the use 
 of a simple make-and-break induction coil in an ignition system. 
 
 17. Describe the appearance of the make-and-break spark as 
 compared with a jump spark. 
 
 18. What causes the high-tension spark when the current in the 
 make-and-break coil is suddenly broken? See Practical Physics, 
 Millikan, Gale, and Pyle — Self-induction. 
 
 ig. Make a diagram showing parts of a make-and-break ignition 
 system? 
 
 C. Automobile Ignition Coil with Timer for Make and Break. 
 
 Mount a spark plug on a ring stand. Attach one secondary binding 
 
 ^ ^/^ Fine Wire 
 -- . .• > Winding 
 
 Battery 
 
 Breaker Points 
 
 Fig. 35. — Induction coil for jump spark in which the primary circuit is broken by 
 means of a cam as in the timer of an automobile. 
 
 post of the automobile coil to the spark plug. Run another wire 
 from the other secondary post to the ring stand to complete the 
 secondary circuit. Attach one terminal of a four-cell battery to 
 one of the primary posts of the coil. Take an insulated wire from 
 the other battery terminal and quickly make and break the 
 primary circuit. Note whether a spark is produced at the spark 
 plug. This kind of induction coil is generally used in automobile 
 ignition systems. On the automobile a device called the timer is 
 used to make and break the primary circuit. A condenser is 
 placed across the contact points of the timer. 
 
STORAGE BATTERY 77 
 
 20. Make a diagram of an automobile induction coil with timer 
 mechanism including breaker points, contact arm, and condenser 
 shown in the primary circuit. See The Gasoline Automobile. 
 
 32. IGNITION SYSTEMS— C. STORAGE BATTERY 
 
 MATERIALS. Atwater-Kent Ignition unit, Type CC; four dry cells; 
 six spark plugs; ring stands; wires. 
 
 A. Atwater-Kent Ignition System, Type CC. Read The 
 Gasoline Automobile on this ignition system. Study the diagrams 
 and set up the system as follows: Remove the small wire-outlets 
 from the distributor cap and attach seven wires to the distributor 
 binding posts. Connect the center distributor wire to the second- 
 ary terminal of the coil. Attach the remaining six wires to six 
 spark plugs mounted on six separate ring stands. Ground the 
 secondary circuit of the coil from the ring stands back to the metal 
 of the ignition unit. Attach one terminal of a battery consisting 
 of four dry cells to the top of the coil and the other terminal to the 
 base of the ignition unit. (Note. In most automobiles a storage 
 battery is used instead of dry cells. Dry cells are used in this 
 experiment merely for convenience.) Turn the timer shaft and 
 see that the spark plugs are firing. 
 
 1. What is the source of low-tension current in this system? 
 
 2. What is the source of high-tension current in this system? 
 This form of ignition system is used on most cars that are equipped 
 with storage batteries. The coil is sometimes placed on the 
 instrument board. 
 
 B. The Timer. Remove the distributor cap and the distributor 
 arm and study the operation of the timer. Note that the con- 
 denser is enclosed in the timer housing. 
 
78 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 3. Which circuit does the timer make and break? 
 
 4. Explain the principle of the condenser. See Practical 
 Physics, MiUikan, Gale, and Pyle— Induction Coil. 
 
 5. What is the function of a condenser connected across the 
 contact points of an induction coil or of a timer in an ignition 
 system? See Practical Physics, MiUikan, Gale, and Pyle. 
 
 SPARK PLUGS 
 3 2 
 
 IGNITION SWITCH 
 
 — DISTRIBUTOR 
 
 BREAKER 
 
 INDUCTION COIL 
 
 Fig. 36. — Atwater-Kent ignition system, Type CC. 
 
 6. Diagram an induction coil with vibrator and condenser. 
 
 7. Examine the timer on the car in the laboratory. To what 
 shaft is it attached? 
 
 8. State four possible firing orders for six-cylinder engines. 
 Arrange the wiring to give one of these firing orders. 
 
 9. What is the shape of the Atwater-Kent timer cam in this 
 
STORAGE BATTERY 79 
 
 unit? How many times does it make and break the circuit during 
 one revolution? 
 
 10. How many times should a six-cylinder engine fire during 
 one revolution of the engine crankshaft? A four-cylinder engine? 
 
 11. How many times should this timer revolve while the crank- 
 shaft makes one revolution? 
 
 12. What would be the shape of the timer in this type of ignition 
 unit for a four-cylinder engine? 
 
 13. What provision is made in this mechanism for the advanc- 
 ing and retarding of the spark? 
 
 14. Trace the primary circuit in an automobile from the positive 
 battery terminal through the entire ignition circuit and back to the 
 negative terminal, naming the parts of the circuit through which the 
 current passes. 
 
 C. The Distributor. Replace the distributor arm and study 
 the operation of the distributor. 
 
 15. In which circuit is the distributor — primary or secondary? 
 
 16. To what shaft is the distributor arm attached? 
 
 17. What is the function of the spring located on top of the 
 distributor arm? 
 
 18. By naming the parts through which it passes, trace the 
 secondary circuit from the terminal at the side of the coil until it 
 returns to the base of the coil. See diagram, The Gasoline Auto- 
 mobile. 
 
 19. Make a complete diagram of the Atwater-Kent ignition 
 system. See Fig. 36. 
 
8o 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 33. IGNITION SYSTEMS— D. FORD CAR 
 
 The Ford Ignition System 
 
 MATERIALS. Five dry cells; ring stand; spark plugs; Ford engine with 
 coil box mounted on the chassis frame (demonstration car in the laboratory) ; 
 wires. 
 
 The Ford ignition system includes a low-tension magneto gener- 
 ator, a dry-cell battery or storage battery, four induction coils, 
 spark plugs, timer, and ignition switch. 
 
 IgniHon 
 
 Pr'imarj/ Circuit 
 
 r4 
 
 ^xTjuiTtiruir^ — \^~ 
 
 Baffery 
 
 INJUCTIgN Cp/lS y. 
 
 *iii 
 
 ;J 
 
 T/mer 
 Oround Return 
 
 ^Secondary 
 
 'Primary 
 Terminals 
 
 Fig. 37. — The Ford ignition system. Note that the upper terminal of the induction 
 coil serves for both the primary and the secondary circuits. 
 
 A. Ignition Circuits. Connect five dry cells in series. Attach 
 one terminal of this dry-cell battery to one of the primary binding 
 posts of the induction-coil box (either one of the two lowest posts 
 on the box). Mount a spark plug on a ring stand. Attach one 
 end of a wire to the secondary binding post of one of the induction 
 coils (any one of the middle row of binding posts) and the other 
 end of the wire to the spark plug. Connect a wire from the metal 
 of the ring stand to the metal of the car frame. This completes the 
 secondary circuit. Now attach an insulated wire to the other 
 terminal of the battery and touch this wire to the proper one of 
 
FORD IGNITION 
 
 the upper row of posts, being very careful not to touch the secondary 
 circuit while the primary circuit is closed. This should produce a 
 spark at the spark plug. 
 
 5l 
 
 I. Trace the primary circuit in the above arrangement from 
 the positive terminal of the battery back to the negative terminal 
 
82 AUTOMOBILE LABORATORY MANUAL 
 
 of the battery by naming in order the parts through which it 
 passes. 
 
 2. Trace the secondary circuit in the same manner, beginning 
 at the secondary terminal of the induction-coil box. 
 
 3. Remove one of the induction coils from the case. Make a 
 diagram of the induction coil showing the primary and secondary 
 terminals. One of the three terminals serves for both primary 
 and secondary currents. See The Gasoline Automobile. 
 
 4. Make a complete wiring diagram of the apparatus used in 
 this experiment. 
 
 B. The Ford Magneto. The Ford magijeto furnishes the 
 primary current for the induction coils after the engine is started. 
 It consists of sixteen small coils of wire wound around soft iron 
 cores which are supported on an iron frame on the engine, and six- 
 teen permanent horseshoe magnets which are attached to the fly- 
 wheel and revolve with it. The magnets revolving in front of the 
 armature coils induce an alternating current in the coils. The 
 coils are connected in series, one end being connected tp the metal 
 of the car (grounded) . The other end is connected to the insulated 
 binding post of the flywheel housing from which the current 
 supply is carried to the induction-coil box. The current returns 
 from the induction coils to the magneto coils by a grounded circuit 
 through the frame of the car. 
 
 With the spark plug arranged as in A of this experiment sub- 
 stitute the magneto for the dry cells by attaching the wire from the 
 magneto binding post to one of the primary binding posts of the 
 induction-coil box. See that the other primary binding post of 
 the coil that you are using is grounded to the frame of the car. 
 Use the crank to revolve the fl3nvheel as rapidly as you can. Sparks 
 should be produced at the spark plug. 
 
 5. Turn the crank at different speeds and state whether low 
 or high speed gives the better spark. Why? 
 
FORD IGNITION 83 
 
 6. Why is a Ford car usually hard to start by cranking if the 
 magneto current is used for ignition when starting? 
 
 C. The Ford Ignition System. Attach both battery and 
 magneto to the induction coils as in A and B of this experiment. 
 Attach four wires from the four upper primary binding posts of the 
 coil box to the four posts of the timer cap on the front of the engine. 
 Do not permit the ends of the wires at the timer posts to touch the 
 metal of the engine or the metal body of the timer cap. Attach 
 wires from the four secondary binding posts of the coil box to the 
 four spark plugs on the engine. Turn the ignition switch so that 
 the battery supplies the current for ignition and touch each post 
 of the timer in turn with the wire from the battery and notice that 
 the spark plugs fire. Turn the switch so that the magneto supplies 
 the current for ignition and with the crank revolve the flywheel 
 and notice that the four spark plugs are firing. The firing order 
 of the Ford, beginning with the front cylinder as No. i, should be 
 I, 2, 4, 3. If your firing order is not correct, arrange the wires 
 from the coil to the timer so that the firing order will be correct. 
 Remove the timer cap and examine the action of the timer roller 
 when the crank is turned. Now attach the wire from the battery 
 to any part of the metal of the engine or frame. If the ignition 
 switch is in the proper position the plugs should spark in the proper 
 sequence when the engine is cranked. 
 
 7. What is the purpose of the timer? What is the function of 
 the roller in the timer? 
 
 8. With respect to the speed of the crankshaft at what rate 
 does the timer arm revolve? 
 
 9. To what shaft is the timer attached? What causes this 
 shaft to revolve? 
 
 10. What other function does this shaft perform? 
 
 11. Locate the four inlet valves by observing the two openings 
 into which the intake manifold leads. By turning the crank 
 
84 AUTOMOBILE LABORATORY MANUAL 
 
 determine in what order the inlet valves open beginning with the 
 front cylinder as No. i. State this order. 
 
 12. How should the firing order compare with the order in which 
 the inlet valves open? If the firing order of an engine is not known 
 how can it readily be determined? 
 
 13. What is the function of the ignition switch? Why should it 
 always be turned off when the car is not running? 
 
 14. When should the battery be used on a Ford car? 
 
 15. Is the timer of the Ford placed in the primary or the second- 
 ary circuit of the coils? 
 
 D. Ignition Troubles. Reference: Dyke. See also Ford 
 Supplement. 
 
 16. Give four possible causes for the spark plugs missing fire. 
 
 17. Tell how you could locate a missing cylinder. 
 
 18. How could you test a spark plug? 
 
 19. Tell how you could determine whether or not the battery 
 is weak. 
 
 34. IGNITION SYSTEMS— E. LOW-TENSION MAGNETO 
 AND DRY-CELL BATTERY 
 
 MATERIALS. Low-tension magneto generator and induction coil; ignition 
 switch; timer (attached to magneto); distributor (attached to magneto); 
 ring stands; spark plugs; wires; five dry cells. 
 
 A. Remy, Model RL, Ignition System. Read The Gasoline 
 Automobile on this system. After studying the diagram attach the 
 induction coil to the magneto. Connect the five dry cells to the 
 primary circuit of the coil. Mount four spark plugs on four 
 separate ring stands. Attach the center distributor wire to the 
 secondary circuit of the coil and the remaining four distributor 
 wires to the four spark plugs. Ground the secondary circuit from 
 the ring stands back to the metal of the ignition switch and coil. 
 
LOW-TENSION IGNITION 
 
 8S 
 
 Attach the three wires from the magneto to the proper bmding 
 posts of the coil. Operate the system by revolving the armature 
 
 shaft of the magneto (by hand) with the switch on magneto {M) and 
 then on battery (5) and see that it works in both cases. See Fig. 73. 
 
 I. State one advantage and one disadvantage of this kind of 
 ignition system. 
 
86 AUTOMOBILE LABORATORY MANUAL 
 
 2. Why must dry cells be used in this system? 
 
 3. Explain how the magneto is connected to the automobile. 
 
 B. Timer and Distributor. 
 
 4. In which circuit of the coil is the timer? the distributor? 
 
 5. Will either the battery or the magneto produce a spark if the 
 yellow cord ( F) is disconnected? the red cord (R)? the green 
 Cord (G)? Test by disconnecting proper wires. 
 
 6. Where would you look first for a disconnected cord if 
 (a) only the magneto worked? (6) only the battery? (c) neither 
 magneto nor battery? 
 
 7. What are the two possible firing orders of four-cylinder 
 engines? Connect the distributor wires to the proper spark plugs 
 to give these firing orders. 
 
 8. To what shaft is the timer attached? 
 
 9. Note the ohape of the timer cam and tell how many times it 
 makes and breaks the primary circuit in one revolution. 
 
 10. How many times does a single-cylinder four-stroke engine 
 fire during one revolution of the crankshaft? a two-cylinder 
 engine? a four-cylinder engine? a six-cylinder engine? 
 
 1 1 . How many times should this timer revolve while the crank- 
 shaft of a four-cylinder engine makes one revolution? a six-cylinder 
 engine? 
 
 12. Carefully take off the distributor cap by removing the two 
 large screws at the sides and explain how the distributor is operated. 
 After observing this mechanism replace the distributor cap and the 
 screws. 
 
 A low-tension alternating-current magneto of this type is some- 
 times used on trucks which are not provided with a storage battery. 
 The engine must be cranked by hand. Most automobiles having 
 storage batteries use the storage battery for ignition current on 
 starting. 
 
HIGH-TENSION IGNITION 87 
 
 35- IGNITION SYSTEMS— F. HIGH-TENSION 
 MAGNETOS 
 
 MATERIALS. One or more high-tension magnetos such as the Bosch, 
 type DU4; the Eisemann, type G4; the Berling, type F41 ; the Dixie (inductor 
 type) or the K-W (inductor type) ; reference books and instruction books. 
 
 Caution. Do not operate this magneto while you are or anyone else 
 is touching the secondary circuit, as a severe shock may result. 
 
 Connect the terminals of the distributor with four spark plugs 
 which have been mounted in ring stands as in the preceding ignition 
 experiments. Connect a ground wire from the ring stands back to 
 the metal of the magneto to complete the high-tension circuit. 
 Operate the magneto and see that each plug sparks at the proper 
 time. 
 
 A . Magnetos. 
 
 1. How does a " hot spark " differ in appearance from a " lean 
 spark " ? Does a magneto ignition system give as hot a spark at 
 low speed as at high speed? Why? 
 
 2. Should spark-plug gaps be as wide for magneto ignition as 
 for battery ignition? What is the approximate width of gap for 
 magnetos? See Motor Vehicles. 
 
 3. What does the usual type of high-tension magneto armature 
 have which the low-tension magneto does not have? 
 
 4. Make a simple diagram representing the wiring of a high- 
 tension magneto. See The Gasoline Automobile or Motor Vehicles. 
 Place pencil arrows on the low-tension circuit and ink arrows on 
 the high-tension circuit. 
 
 5. What effect must occur at the interrupter to produce the 
 high-tension current in the secondary circuit? 
 
 6. In approximately what position does the armature core 
 stand when this occurs? 
 
88 AUTOMOBILE LABORATORY MANUAL 
 
 7. What magnetic effect is being produced in the armature at 
 this time? 
 
 8. In which circuit is the switch placed? What is its function? 
 
 9. Why does a magneto interrupter cam usually make two 
 breaks of the contact points per revolution instead of one? 
 
 B. The Bosch Magneto. 
 
 10. Describe the location of (a) the primary coU, (6) the second- 
 ary coil, (c) condenser, id) the interrupter, (e) the distributor. 
 
 11. Explain how the high-tension current is carried from the 
 secondary coil to the distributor arm. 
 
 12. Through how many degrees does the spark advance lever 
 move? 
 
 13. By what kind of bearings is the armature supported? 
 
 14. State the special features of the Bosch High-tension Dual 
 System. See The Gasoline Automobile. 
 
 C. The Dixie Magneto. Stt The Gasoline Automobile. 
 
 15. Where are the coils located in this magneto? 
 
 16. Do these coils move or are they stationary? 
 
 17. Has the rotor of this type of magneto any wire on it? 
 Of what material is it made? What is the function of the 
 bronze center? 
 
 18. With respect to the operation of the coils of this magneto 
 what is the specific function of the rotor as it revolves? 
 
 D. Troubles. 
 
 19. State at least four possible magneto troubles. See The 
 Gasoline Automobile. 
 
STORAGE BATTERY 
 
 89 
 
 36. STORAGE BATTERY— B 
 
 MATERIALS. Storage battery (commercial type preferably in glass jar) ; 
 battery hydrometer; battery ammeter; rheostat. 
 
 Caution. Sulphuric acid will destroy clothing and cause burns. 
 Handle with extreme care. 
 
 A. Operation. Examine the large storage batteries. Test by 
 means of a salt solution, as in Storage Battery — A, to find which 
 
 From Good's "Laboratory Projects in Physics." Used 
 by permission of the Macmillan Company, publisliers 
 
 Fig. 40. — A storage battery operating a motor with an ammeter in the circuit. 
 
 terminal is negative. Test the line current also to find which 
 terminal is negative. With a 3-ampere rheostat in series, prepare 
 to force a current through the battery in reverse direction (positive 
 connected to positive and negative to negative). {Caution. Have 
 your scheme of wiring inspected by an instructor before turning on 
 the current, to avoid a possibility of ruining the batteries.) If 
 
90 AUTOMOBILE LABORATORY MANUAL 
 
 necessary, distilled water should be added so that the electrolyte 
 stands J inch above the plates. The time required for complete 
 charge from condition of discharge is usually fifteen to twenty 
 hours. 
 
 1. Do not attach an ammeter to a storage battery without 
 additional resistance in the circuit. Why? 
 
 2. Record the specific gravity at the beginning of charge. 
 
 3. Charge for fifteen minutes. This brief time will not make 
 a measurable change on the specific gravity. Does the acid be- 
 come more or less concentrated on charging? Refer to texts. 
 
 4. What is the combined voltage of two storage cells in series? 
 
 5. Attach a suitable motor in series with a battery ammeter 
 and operate it. How much current (amperes) does the motor 
 take? 
 
 Storage batteries are commonly rated as having a certain output 
 in ampere-hours. An ampere-hour means a flow of i ampere for 
 one hour. A 20-ampere-hour battery means that the battery can 
 supply a current of i ampere for twenty hours, after which it 
 should be recharged. If larger amperages are taken, the time 
 will be reduced. 
 
 B. Care of Lead Battery, (a) Use only pure water and pure 
 acid for electrolyte, (b) Avoid overcharging and overdischarging. 
 (c) Do not allow the battery to stand discharged, as it will become 
 sulphated and sometimes permanently injured. 
 
 In the self-starting systems of automobiles, storage batteries 
 are required to deUver between 50 and 200 amperes at about 6 volts 
 for a few moments in starting the engine. This large amperage 
 would soon exhaust and injure a storage battery. The starting 
 motor should be operated for very short periods only. Lead 
 storage batteries are well suited for this work, because they can 
 deliver an enormous current for a short time, due to then: very low 
 internal resistance. Automobile storage batteries have a specific 
 gravity at complete charge 1.3, and at complete discharge 1.15. 
 
STORAGE BATTERY 91 
 
 C. Reference Work. The Gasoline Automobile. 
 
 6. What is meant by (a) grid, (b) separator, (c) negative 
 terminal, (d) specific gravity? 
 
 7. What two forms of lead are used in the making of plates? 
 
 8. How does the formation of insoluble lead sulphate reduce 
 the efficiency of the cell? 
 
 9. What is meant by the expression, lo-ampere, eight-hour 
 ceU? 
 
 10. For what length of time should a cell rated at 100 ampere- 
 hours produce a current of 5 amperes? 
 
 11. If cells are discharged too rapidly, what tends to reduce their 
 efficiency? 
 
 37. STORAGE BATTERY— C 
 
 Construction, Operation, Tests, and Troubles 
 
 MATERIALS. Automobile batteries, if possible, one in section; syringe 
 type of hydrometer in a large bottle; reference books. 
 
 The lead storage battery requires exceptional care. Its con- 
 struction and principles should be thoroughly studied by every 
 automobile owner. Of all the automobile equipment there is no 
 more delicate piece of apparatus, and yet, the storage battery, 
 due chiefly to ignorance, is one of the most neglected and abused 
 units of the car. To replace a worn-out battery involves a con- 
 siderable expense that could often be avoided by a few hours of 
 study and attention to a few simple testing operations. Read 
 The Gasoline Automobile and Motor Vehicles. 
 
 I. What proportions of distilled water and sulphuric acid 
 should be used in making up a lead storage battery electrolyte? 
 
92 AUTOMOBILE LABORATORY MANUAL 
 
 2. In the ordinary operation of a car, about how frequently 
 should the storage battery be refilled with distilled water? . 
 
 3. What evidence that a battery is being overcharged may be 
 observed in the action of the electrolyte? 
 
 4. What injurious effect is caused by undercharging a battery? 
 
 5. What is the highest temperature which a storage battery 
 should be permitted to reach? 
 
 6. What is the normal temperature for taking hydrometer 
 readings of a storage battery? 
 
 7.. At what temperature will a battery freeze — (a) if it is fuUy 
 charged? {h) if it is completely discharged? 
 
 8. Under what conditions might a motor-generator be used in 
 charging a storage battery? 
 
 9. Why is it necessary to use a resistance in the circuit in 
 charging a battery with no-volt current? 
 
 10. Make a diagram showing apparatus needed for charging a 
 battery. Indicate the name of each part, including the positive 
 and the negative terminals of the battery and of the supply line. 
 
 1 1 . Explain the meaning of charge rate and finish rate in charging 
 a battery. 
 
 12. State the method of determining when a battery is fully 
 charged with respect to (a) change in voltage and in specific 
 gravity, (b) the voltage with charging current on, (c) gassing, 
 {d) specific gravity. 
 
 13. If, after continuous charging, a battery does not show a suffi- 
 ciently high specific gravity, what is probably needed? 
 
 14. What are the causes of sulphation? How may sulphation 
 be prevented? 
 
 15. Is sulphate a conductor pf electricity? How does this affect 
 the charging of a sulphated battery? 
 
 16. How may a sulphated battery be partly restored? 
 
 17. When a battery is filled, how high should the level of the 
 liquid stand above the plates? If it is filled too full, what trouble 
 occurs when the battery is being charged? 
 
OPERATING A GAS ENGINE 93 
 
 18. What causes battery plates to buckle or warp? 
 
 19. How could one of the cells of a battery be tested to find out 
 ivhether it is " dead " ? 
 
 20. Name ten common causes which tend to overdischarge and 
 injure a storage battery. 
 
 38. OPERATING A GAS ENGINE— TROUBLES AND 
 ADJUSTMENTS 
 
 Study of a Gas Engine in Operation 
 
 MATERIALS. One and one-half horsepower gasoline engine on truck. 
 
 Operate the engine with illuminating gas (or with gasoline) and 
 study its operation and adjustments. 
 
 1. What kind of mixture causes a gas or gasoline engine to 
 " back fire " into the intake manifold and carburetor? 
 
 2. Devise a scheme for causing this engine to " back fire." 
 (Note. If you are in doubt about any procedure in this experi- 
 ment, consult with the instructor before using it.) 
 
 3. Hold your thumb over the air intake and note the effect 
 upon the operation of the engine. How could an automobile 
 driver cause a trouble similar to this while driving? 
 
 4. How could you cause trouble in this engine similar to that 
 which occurs when a carburetor spray needle is too far shut? 
 Try it. 
 
 5. How could you cause trouble in this engine similar to that 
 which occurs when an exhaust valve leaks? What effect is 
 produced? 
 
 6. How could you cause this engine to explode in the muffler 
 as in the case of a leaky exhaust valve? Try it. 
 
 7. How could you cause trouble in this engine similar to that 
 which occurs when an inlet valve leaks? Try it. 
 
94 AUTOMOBILE LABORATORY MANUAL 
 
 8. Is it possible to make this engine "kick back" (revolve in the 
 reverse direction)? Explain. 
 
 9. Does the spark in this engine occur at " top center " of the 
 compression stroke or before " top center "? Give a reason for 
 your answer. 
 
 10. Is there any provision on this engine for timing the ignition? 
 What is it? 
 
 1 1 . What provision is made for timing the exhaust valve? 
 
 12. How could you demonstrate on this engine the effect of 
 weak valve springs? Try it. 
 
 13. Name at least six possible places in the combustion chamber 
 of this engine which might be out of adjustment and cause leakage. 
 
 14. Name at least five ignition troubles which might occur on 
 this engine. Consult The Gasolme Automobile. 
 
 39. ENGINE TROUBLES 
 Reference Work, The Gasoline Automobile. 
 
 A. Classification of Engine Troubles. 
 
 1. Name eleven main groups of s}rmptoms under which engine 
 troubles are classified. 
 
 2. Which of these symptoms may result from carburetor 
 troubles? 
 
 3. Which of these symptoms may result from ignition troubles? 
 
 4. State symptoms which may result from spark-plug troubles. 
 
 5. State symptoms which may result from compression 
 leakage. 
 
 6. State symptoms which may result from valve troubles. 
 
 7. State symptoms which may result from improper lubrica- 
 tion. 
 
 8. State seven possible troubles if an engine knocks. 
 
CHANGE-SPEED GEARS 95 
 
 9. What are the possible troubles if an engine misses at low 
 speeds? 
 
 10. Of what use is such a table of symptoms and troubles to an 
 intelligent repairman? 
 
 B. Engine Trouble Chart, The Gasoline Automobile. 
 
 11. What carburetor troubles are mentioned? 
 
 12. What troubles are represented as pertaining to valves and 
 valve mechanisms? 
 
 13. State troubles pertaining to crankshafts, connecting rods, 
 and pistons. 
 
 14. State troubles pertaining to (a) the cooling system; (6) the 
 ignition system. 
 
 40. CHANGE-SPEED GEARS— A. SELECTIVE 
 
 MATERIALS. Automobile chassis and reference books. 
 
 Practice shifting the gears to obtain the different speeds. Turn 
 the engine over by means of the crank. Open the cylinder pet 
 cocks. 
 
 1. Make a diagram showing the position for low, intermediate, 
 high, and reverse gears. See The Gasoline Automobile. 
 
 2. What are the two common types of gear-shift levers? 
 
 3. What is the location of the gear case in the laboratory auto- 
 mobile? What two other locations are sometimes used? What 
 are the advantages and disadvantages of each type? See Motor 
 Vehicles. 
 
 4. What are the common types of gear transmission? What 
 are the advantages of the selective type:! See Motor Vehicles. 
 
 Transmission gear ratio means the rate of engine or crankshaft 
 speed compared with the rear axle or rear wheel speed. 
 
96 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 5. By counting the teeth determine the gear ratio of the drive 
 shaft pmion (in the differential housing) and the differential ring 
 gear. This is the gear ratio between the driveshaft and the rear- 
 axle shaft. 
 
 6. Determine the gear ratio between the crankshaft and the 
 propeller shaft when the transmission is in high, low, intermediate, 
 and reverse gears. To do this put chalk marks on the propeller 
 shaft and fl3rwheel, then turn the motor by hand and count the 
 number of revolutions of the motor to one revolution of the pro- 
 
 ToDri vex ' \ 
 Reverse Gear 
 
 Jb^i'ne 
 
 Counienshafi 
 
 FIRST SPEED OR 'LOW 
 
 Gears 1-2 and 5-8 in Mesh 
 Fig. 410. — Position of gears in three speed and reverse gear set. 
 First or "low" speed position. 
 
 peller shaft. This should be checked up later by counting the 
 proper gear teeth in the gear case. 
 
 7. State the gear ratio between the crankshaft and the rear 
 axle for high, intermediate, and low gears. 
 
 8. In which gear will the car have the greatest pull — high, 
 intermediate, low, or reverse? Explain. 
 
 Remove the gear-case cover. 
 
 9. What two shafts are found within the gear box? See Motor 
 Vehicles and The Gasoline Automobile. 
 10. How many gears are on each shaft? 
 
CHANGE-SPEED GEARS 
 
 97 
 
 II. Which shaft is in constant motion when the main driving 
 gear is in motion? See Dyke, Transmission. 
 
 'hPri vex ' N 
 (leverfeGear- 
 
 IbErylne 
 
 Counhrshm 
 
 SECOND SPEED OR "INTERMEDIATE* 
 
 Gears 1-2 and 3"4inMesh 
 
 Fig. 4ii. — Position of gears in three speed and reverse gear set. 
 Second or " intermediate " speed position. 
 
 12. Which shaft has gears that shde back and forward? How 
 many shding gears does it have? 
 
 Shaft ^ — :) 
 Averse Gmr 
 
 ToEnsfne 
 
 THIRD OR 'HIOH SPEED" 
 Gears 1-4 Ccmeded b 
 
 Fig. 41C. — Position of gears in three speed and reverse gear set. 
 Third or " high " speed position. 
 
 13. What is the function of these shding gears? 
 
 14. Which speeds does the front shding gear control? 
 
98 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 15. Which speeds does the rear sliding gear control? 
 
 16. How does the reverse gear system work? 
 
 IbVr/ve x ' \ 
 
 Jb^lne 
 
 REVERSE 
 
 Gears 1-2 and 6-7-8 in Mesh 
 
 Fig. 4i(i. — Position of gears in three speed and reverse gear set. 
 Reverse speed position. 
 
 17. What are the dogs on the front sliding gear, and what is 
 their purpose? See Motor Vehicles. 
 
 --•j^offs for High SpesJ 
 
 ■JoDr/veA \ 
 6haft^Tl=J 
 
 /Averse Oear- 
 
 TbEngine 
 
 Qounfehsha) 
 
 NEUTRAL 
 
 Gears 1-2 in Mesh 
 
 Fig. 4ie. — Position of gears in three speed and reverse gear set. 
 Neutral Position. 
 
 18. Make a diagram showing a selective type of transmission with 
 the gears in neutral. 
 
CHANGE-SPEED GEARS 99 
 
 41. CHANGE-SPEED GEARS— B. FORD TRANSMISSION. 
 The Planetary Gears and the Clutch 
 
 MATERIALS. Ford chassis and reference books. 
 
 Operate the gears of the Ford car in the following manner: 
 By means of a suitable bolt compress one of the brake bands so 
 that it grips the middle one of the three drums. This causes the 
 planetary gear mechanism to operate the drive shaft in " low 
 gear." (The drive shaft goes slower than the crankshaft or engine.) 
 
 1. Place a chalk mark on the clutch housing or brake drum. 
 Let one person crank the engine over eleven turns while the other 
 counts the number of revolutions made by the clutch housing and 
 consequently the drive shaft. What is the gear ratio of low 
 gear between the crankshaft and the driveshaft on the Ford car? 
 
 2. In the operation of a set of gears the pull is increased in the 
 same ratio as the speed is decreased (friction not being considered). 
 If we do not consider waste power due to friction how much greater 
 should a Ford car be able to pull when it is in " low " than when 
 it is in " high " ? Does friction make the actual force or push of 
 the rear wheels greater or less than this amount? 
 
 3. Move the brake band to the drum nearest the flywheel. 
 Crank the engine as before. When this drum is prevented from 
 revolving, what effect is produced upon the direction of motion of 
 the clutch housing and consequently of the drive shaft? 
 
 4. In the same manner as before determine the gear ratio 
 when the gears are operating in reverse. 
 
 5. On the basis of the reverse gear ratio how much greater 
 should the Ford car be able to push than to pull in high (friction 
 not being considered)? 
 
 6. If a Ford car is unable to go up a steep hill in low gear, it is 
 sometimes possible to back the car up the hill. Explain. 
 
AUTOMOBILE LABORATORY MANUAL 
 
 7. What is the purpose of the third brake drum — the one far- 
 thest from the flywheel? 
 
 B. The Ford Clutch. Multiple Disc, Dyke. 
 
 8. Where is the clutch located in the Ford transmission? See 
 Motor Vehicles and Dyke's Ford Supplement. 
 
CHANGE-SPEED GEARS loi 
 
 9. Note that a shaft called the transmission shaft extends from 
 the flywheel through the gear mechanism into the clutch housing. 
 This shaft is connected to the flywheel and therefore must run 
 with the crankshaft and at the same speed as the crankshaft. 
 Which of the clutch plates or discs are attached to the end of the 
 transmission shaft? How many of these discs are used? 
 
 10. To what part of the transmission assembly are the large 
 clutch discs attached? How many of these are used? 
 
 11. When the engine is running in high gear how is the con- 
 nection made between the transmission shaft and the drive shaft? 
 
 12. What parts of the mechanism keep the clutch engaged? 
 
 13. In operation of the car what two levers compress the clutch 
 spring and disengage the clutch? 
 
 42. CHANGE-SPEED GEARS— C. FORD TRANSMISSION 
 The Planetary Gears and the Clutch 
 
 MATERIALS. Ford chassis; reference books and the i^ord: If aK«oZ. 
 
 A, The Ford Gears. This type of gear mechanism has been 
 called planetary on account of a fanciful resemblance to the 
 planets revolving around the sun in the solar system. The Ford 
 transmission provides for high, low, and reverse. High speed is 
 obtained by a direct connection with the clutch by means of the 
 " transmission shaft." See Dyke. The gear mechanism provides 
 for low speed and reverse. With a suitable bolt compress the 
 brake bands and observe the operation of the gear mechanism. 
 
 I. How many sets of triple gears are provided on the Ford? 
 Note that these triple gears are set on shafts which are fastened 
 to the flywheel. The triple-gear shafts must therefore move when 
 the crankshaft and the flywheel move. Note that the three 
 wheels which constitute each triple gear are all fastened together 
 
I02 AUTOMOBILE LABORATORY MANUAL 
 
 into a single unit. They all move together at the same rate and 
 in the same direction. 
 
 2. Release the brake bands from the low and the reverse drums 
 and crank the engine in high gear. In high gear do the triple 
 gears revolve on their shafts? 
 
 3. When do the triple gears sets revolve on their shafts? 
 
 4. Do they revolve on their shafts in the same direction in both 
 " low " and " reverse " ? 
 
 Triple Gear 
 
 Brake Drum 
 
 C/ufch Discs 
 
 Cluhh Push Ifihg 
 
 .'Clutch Firjger 
 
 Engine 
 Crank 
 Shaff. 
 
 ClufchSpnh^ 
 
 Clutch ■Shift- 
 
 Fig. 43. — Diagram showing the principle of the Ford transmission. 
 
 5. How many center gears (" sun gears ") are provided? 
 Note that each gear of a triple-gear set engages with a center gear. 
 One center gear connects with the clutch housing; one connects 
 with the low-speed drum; and one connects with the reverse drum. 
 
 6. Which one of the triple gears is the largest? Which is the 
 smallest? 
 
 7. Which of the center gears (sun gears) is the largest? Which 
 '6 the smallest? 
 
CHANGE-SPEED GEARS 103 
 
 8. Are the three center gears fastened together like the triple- 
 gear sets or do they move separately? 
 
 9. Which of the three center gears is connected with the clutch 
 housing and therefore may move with the propeller shaft? 
 
 10. Which of the three center gears is connected with the low- 
 gear drum? Which with the reverse drum? How can you show 
 this definitely by experiment? 
 
 11. Place a brake band on the low-gear drum and bolt it, holding 
 the drum still. Which of the three center gears is held still? 
 
 12. When the engine is now cranked do the triple gears revolve 
 clockwise or counterclockwise (looking at them from the rear of the 
 car)? 
 
 13. What causes the triple gears to revolve in this case? 
 
 14. In which direction does this cause the center gear nearest 
 the flywheel to revolve (clockwise or counterclockwise) ? Note that 
 this gear is attached to the clutch housing and to the drive shaft. 
 Does this gear revolve at the same rate as the flywheel? What is 
 its ratio? 
 
 15. Now clamp the brake band on the reverse drum and crank 
 the engine. Which of the center gears is held stationary? 
 
 16. Do the triple gears revolve clockwise or counterclockwise? 
 Note that they revolve faster than in the case of low gear. 
 
 17. In which direction does this cause the center gear which con- 
 trols the drive shaft to revolve? 
 
 B. The Clutch. The Ford clutch can be engaged only in high 
 gear. In low and reverse it must be released. 
 
 18. Explain why the clutch must be released when the gears are 
 in low or reverse. 
 
 19. What disengages the clutch when low gear is used? 
 
 20. What disengages the clutch when reverse is used? 
 
104 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 43. CLUTCHES 
 The Multiple Disc Clutch and the Cone Clutch 
 
 MATERIALS. The Ford chassis; the Ford Manual and reference books. 
 
 A. The Multiple Disc Clutch— Disassembling the Ford Clutch. 
 
 See Fig. 42. Raise the rear end of the motor and support it so 
 that the clutch will be accessible. This may be done by removing 
 the bolts between the engine block and the crankcase. Then raise 
 
 ClufchDisc 
 
 Fig. 44. — ^A multiple-disc clutch. 
 
 the rear end of the engine and place a board under the transmission 
 drums. Follow the directions in the Ford Manual for disassembling 
 the clutch mechanism. Remove the driving plate, then remove 
 the push ring. 
 
 Note. Place all bolts and parts carefully and orderly on a news- 
 paper to avoid losing them and to aid in reassembling. Then 
 remove the clutch discs. When the clutch is completely disas- 
 sembled, have the work inspected by the instructor. For reference, 
 use the Fori Manual and Motor Vehicles. 
 
CLUTCHES 
 
 I OS 
 
 How many discs does the Ford have? 
 
 What is the purpose of the large discs? of the small discs? 
 
 3. To what are the large discs comiected? 
 nection made? 
 
 How is this con- 
 
io6 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 4. To what are the small discs connected? How is this connec- 
 tion made? 
 
 5. Of what material are the discs made? 
 
 Reassemble the clutch and have your work inspected and 
 approved by the instructor. Do not continue further until this is 
 done. 
 
 6. What is the purpose of the clutch? 
 
 7. Describe the relative positions of the large and small discs 
 when the clutch is engaged and when disengaged. 
 
 Clutch "IN 
 
 Fig. 46.— Cone dutch showing "in" and "out" positions. 
 
 8. What releases the plates? What engages the plates? ' 
 
 9. How are the discs held in contact? 
 
 10. What would be the result if the discs did not engage closely 
 or firmly? How may this defect be remedied? 
 
 11. Does the clutch need to be lubricated? If so, what means 
 are provided for lubrication? 
 
 12. In the operation of the clutch mechanism state the purpose 
 of: (a) the discs; {b) the clutch release plate; (c) the clutch fork; 
 {d) the spring; (e) the clutch shift; (/) the clutch finger. 
 
 13. Explain how the emergency-brake lever releases the clutch. 
 Why is it necessary to do this? 
 
CLUTCHES 
 
 107 
 
 14. What is the position of the clutch when the Ford car is 
 running (a) in low gear; (6) in reverse gear; (c) in high gear? Is 
 it the same in the case of other cars? 
 
 B. The Cone Clutch. Read The Gasoline Automobile on the 
 cone clutch. If possible, examine a cone clutch. 
 
 f Flywheel' 
 
 '1- 
 'Clutch lea/he. 
 
 Clutch . cone 
 
 Clutch release 
 
 Tr-ansmiss/on 
 
 Fig. 47. — A typical cone clutch. 
 
 15. What are the two most common types of clutches? 
 
 16. Why is this mechanism called a cone clutch? How many 
 degrees, approximately, does it taper? 
 
 17. What materials are used in facing cone clutches? 
 
 18. What holds a clutch engaged and what releases it? 
 
 19. Do cone clutches operate dry or in oil? 
 
io8 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 20. Make a simple diagram of a cone clutch mechanism with 
 parts labeled. 
 
 44. BRAKE MECHANISMS— B 
 
 Brakes Used on the Larger Cars 
 
 MATERIALS. Automobile chassis; reference books. 
 
 Brakes which do not operate properly when an emergency arises 
 are responsible for a large proportion of automobile accidents. 
 
 CONTRACTING BRAKE 
 BAND FOR 
 GENERAL SERVICE 
 
 'RVICE BRAKE 
 RODS 
 
 EXPANDING BRAKE 
 BAND FOR 
 EMERGENCY 
 
 SERVICE 
 i 0RAKE PEDAL 
 
 Fig. 48. — Braking system on Cadillac eight. 
 
 Brakes that are too tight will cause loss of power and unnecessary 
 wear on the friction surfaces. Examine the illustrations of brake 
 mechanism in the reference books. 
 
 Remove the hub cap and the lock nut from one of the rear wheels 
 of the large laboratory automobile. Take off the wheel. For this 
 work get directions from the instructor. Place all nuts, screws, and 
 
BRAKE MECHANISMS 
 
 109 
 
 small parts on a table to avoid losing them. As a reference book 
 for this work use Dyke. 
 
 1. What prevents the lock nut from coming off when the car is 
 in operation? 
 
 2. Examine the brake mechanism. Name the two general 
 classes of brake mechanisms. In this car which of the two is used 
 for service brake and which for the emergency brake? 
 
 Drum^ 
 
 Fig. 49. — ^Types of expanding and contracting brakes. 
 
 3. State the function of the following parts of a brake mechan- 
 ism: brake band lever, release spring, cam, or toggle mechanism. 
 
 4. With what material are brake bands commonly lined? 
 
 5. What are the characteristics of an ideal brake lining? 
 
 6. In this braking system how many brake-rods or cables 
 extend between the brakeshaft and the brakes? 
 
 7. When the driver applies the brakes by what means is the 
 force carried to the brakeshafts? 
 
no AUTOMOBILE LABORATORY MANUAL 
 
 Replace the wheel on the hub with key and lock nut in proper 
 position. Have the work approved by the instructor before put- 
 ting on the hub cap. 
 
 Troubles and Adjustments. 
 
 8. What are four troubles usually experienced with brakes? 
 See texts. 
 
 9. Explain the cause of each of these troubles. 
 
 10. How may each of these troubles be remedied? 
 
 11. What means may be employed for saving the brakes in 
 descending a long hill? 
 
 12. If a car tends to skid or swing to one side when the brakes 
 are set, what defect in the brake adjustment may be the cause? 
 
 13. Explain how a brake equalizer provides equal tension upon 
 both brakes. See Dyke. 
 
 14. If the brake band should be too tight when the brakes are 
 in the " off " position locate the stop screw by which the band may 
 be set looser. A band should show a clearance of about xg- inch all 
 the way around when released. It should take hold evenly all the 
 way around when brakes are applied. 
 
 15. Have the external brake rods or cables inspected by the 
 instructor. If they are properly equalized set them so that the 
 external brakes apply unequally, then equalize them. If they are 
 unequally set equalize them. State your procedure. 
 
 45. COMPRESSION— A 
 Simple Tests of Compression 
 
 MATERIALS. Laboratory automobile engine and reference books. 
 
 In the operation of the engine the intake stroke of the piston 
 carries the mixture into the cylinder. Then the intake valve 
 closes and, as the piston comes up on the compression stroke, the 
 charge is compressed in the upper end of the cylinder. At the end 
 
COMPRESSION III 
 
 of the compression stroke the firing or power stroke occurs and the 
 piston is forced downward by the explosion. If, for any reason, 
 leaks occur around the pistons, valves, or other points in the 
 combustion chamber, the engine will waste gasoline and conse- 
 quently lose power. Compression losses become very large in the 
 case of old or abused engines. 
 
 A . Compression. The piston is at top center on the compres- 
 sion stroke approximately one revolution after the intake valve 
 begins to open. Make a simple compression test as follows: 
 Open the throttle completely and turn off the ignition switch. 
 Open all compression or priming cocks except the one on the 
 cylinder which you wish to test. Note when the intake valve 
 for that cyhnder opens. Turn slowly one revolution further, 
 noting the effect as compression is passed. 
 
 I. Describe the condition of the compression in the case of each 
 of the four cylinders, beginning with the front as No. i. If it 
 turns through compression easily write " poor compression." If it 
 passes compression with difficulty and with springy resistance 
 write " good compression." 
 
 2. Name six different kinds of compression leaks. See Motor 
 Vehicles. 
 
 3. How may leaks past gaskets, valve caps, spark plugs, priming 
 cocks, etc., be detected? 
 
 4. If none of the leaks mentioned m question 3 exist, how can 
 you next test for piston leak? 
 
 5. Name two other possible causes of compression leakage. 
 
 6. Name three possible causes of valve leakage. 
 
 B. Compression Test. Test the compression of the laboratory 
 automobile engine as follows: Proceed as above and stop the piston 
 at top center on the compression stroke. This may require some 
 practice to avoid letting the piston slip past top center. Let your 
 associate hold a watch having a second hand. When the piston 
 
112 AUTOMOBILE LABORATORY MANUAL 
 
 stops at top center give him the signal to count fifteen seconds at 
 the end of which he is to open slightly the compression cock and 
 listen for a hissing sound as air escapes. If a hissing sound is 
 heard, test again, waiting twenty seconds. If no sound is heard 
 at fifteen seconds test again at ten seconds. 
 
 7. For each cylinder make a record of the number of seconds 
 during which it holds compression. Ten seconds may be con- 
 sidered " fair compression "; fifteen seconds " good " and twenty 
 seconds or more " very good." 
 
 Note. Try the spark plugs with an end wrench to see if they 
 are fitting tightly. 
 
 The most common causes of poor compression are leakage at 
 the valves and in old engines leakage between the piston and the 
 cylinder wall. Valve leakage is frequently due to pitted valve 
 face or valve seat which may be corrected by grinding. Valve 
 leakage may also be due to a weak valve spring or to warping of the 
 valve. 
 
 46. COMPRESSION— B 
 
 MATERIALS. Laboratory automobile engine and reference books. 
 
 If the throttle is open the maximum compression for the common 
 automobiles at top center at the end of the compression stroke 
 should be between 70 and 100 lbs. per square inch. Engines that 
 are designed for slow speed have low compressions and those 
 designed for high speed have high compressions. When explosion 
 occurs the pressure immediately increases to about 250 or 300 lbs. 
 per square inch at the beginning of the power stroke. The initial 
 pressure at explosion will depend upon the degree of compression 
 and upon the proper proportioning of the mixture in the carburetor 
 as well as the speed of the engine. A very lean or a very rich 
 mixture explodes or burns slowly in the cylinder. 
 
COMPRESSION 113 
 
 A. Reference Work. Use Dyke. 
 
 1. What are the advantages of high compression? 
 
 2. What are the disadvantages of high compression? 
 
 3. State the maximum compression for the following makes of 
 cars — Hudson, Chalmers, Packard, Ford (see Ford Supplement for 
 Ford). 
 
 4. What are the evidences of a hole in the cylinder wall? 
 
 5. An explosion from the engine through the intake manifold 
 into the carburetor may indicate what compression defect? How 
 may a very lean mixture produce a similar effect? 
 
 6. An explosion in the exhaust pipe and muffler may be due to 
 what compression trouble? Can you suggest another method of 
 getting an explosion in the exhaust pipe? 
 
 7. How may a piece of rubber hose be used for detecting a leak 
 in the inlet or in the exhaust valves? 
 
 8. If piston rings are loose and allow an excess of oil to pass from 
 the crankcase past the piston into the combustion chamber, what 
 trouble is Hkely to result? 
 
 9. How may a valve seat be tested for leakage by the use of 
 Prussian blue? by lead-pencil marks? 
 
 10. What is a compressometer? 
 
 1 1 . How does high compression affect the flow of spark current 
 between the terminals of the spark plug? Which has the higher 
 resistance to the flow of the spark current— high compression or 
 low compression? 
 
 12. What adjustment should be made at the spark points for 
 very high compression? 
 
 13. If a spark plug just barely sparks when it is taken out and 
 laid on the engine, does it necessarily follow that it will spark in 
 the engine under operating conditions? Explain. 
 
 B. Troubles. 
 
 14. Refer to the classification of troubles in The Gasoline 
 Automobile Sf.nd list the common engine troubles which may be 
 due to compression trouble. 
 
114 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 47. TIRES— A 
 
 Manipiilation 
 
 MATERIALS. Ford wheel with clincher rim; tire tools; tire pump; 
 reference books. 
 
 A. Removing a Clincher Tire from the Wheel. Read The 
 Gasoline Automobile on The Clincher One-piece Rim, including 
 the directions for removing the tire. 
 
 (a) First jack up the wheel clear of the road. The valve cap 
 should be unscrewed, the lock nut removed, the tire deflated, and 
 
 Second Position 
 of Tire Tool 
 
 Fig. so. — Method of removing tire from clincher rim. 
 
 the valve stem pushed into the rim. When this is done loosen up 
 the bead of the shoe in the flange of the rim by working and pushing 
 with the hands, then insert one of the tire irons or levers under the 
 head. Special care must be taken in inserting the levers to avoid 
 pinching or cutting the inner tube. The tire iron should be 
 pushed in just far enough to get a good hold on the under side of 
 the bead, but not so far as to pinch the inner tube between the 
 rim and the tool. A second iron should be inserted in the same 
 
TIRES 115 
 
 manner 7 or 8 inches from the first, and a third tool the same 
 distance from the second. As a cHncher tire must always be pried 
 over the flange, two or three levers will be needed and the knee of 
 the operator should be used to hold down one lever while the other 
 two are being manipulated in working the tire clear of the rim. 
 After freeing a length of the bead from the rim, the entire outer 
 edge of the casing may be removed by the hands. 
 
 (b) Beginning at the point on the side of wheel diametrically 
 opposite the valve pull out the inner tube carefully until all that 
 remains in the casing is the section containing the valve. Remove 
 the latter by inserting your hand in the casing and grasping the 
 base of the valve firmly and lifting the valve out of the hole in the 
 felloe of the wheel. It may then be removed from the casing in 
 the same manner as the rest of the tube was removed. Remove 
 the casing from the rim by levering the inner side of the casing over 
 the outer flange of the rim in the same manner as before. 
 
 (c) Pump up the inner tube until it is well filled out for testing 
 purposes and test it for leaks in a pan of water. Should there be a 
 puncture, notify the instructor and show the exact location of the 
 puncture. Test the valve for leakage in the same manner as in 
 testing the tire. 
 
 (d) Inspect the casing for cuts or breaks. Pass your hand over 
 the complete inner lining of the casing carefully, in order to ascer- 
 tain whether or not any sharp particles (tacks, nails, pebbles, glass, 
 etc.) have penetrated the casing. 
 
 1. Write a report on the condition of the casing and inner tube. 
 Replace the tire on the rim, performing the operations in the 
 reverse order from that used in taking it off. Get a pump from the 
 instructor for pumping up the tire. 
 
 B. Reference Work. The Gasoline Automobile; Motor Vehi- 
 cles; Dyke. 
 
 2 . What is meant by bead of a tire? 
 
Ii6 AUTOMOBILE LABORATORY MANUAL 
 
 3. What is the difference between a straight side tire and a 
 dincher tire? 
 
 4. What causes " pinching " of the inner tube? 
 
 5. Why is talc or soapstone used between the inner tube and the 
 casing? 
 
 6. How should inner tubes be carried in the car? 
 
 7. State the function of : (a) the bead filler, (b) the valve cap, 
 (c) the tread, (d) the fabric, (e) the valve spring. 
 
 48. TIRES— B 
 
 Testing, Patching, and Vulcanizing Tires 
 
 MATERIALS. Inner tube; pail; tube bag; cement and patches; five- 
 minute vulcanizing apparatus. 
 
 A . Testing the Tire for a Puncture. Ask the instructor for an 
 inner tube. Test it for punctures by passing it through a pail of 
 water. Place your finger over the puncture; if one is found, take 
 the tube to the instructor. After he has examined it, deflate the 
 tube by removing the valve plunger, roll up the tube, thus expelling 
 all the air, and insert the valve plunger, screwing it firmly into its 
 seat. 
 
 After drying the tube fold it in the correct manner (see The 
 Gasoline Automobile), tie it together, place it in the bag, and 
 return it to the instructor. 
 
 B. Patching the Tube. The instructor will supply you with 
 another tube or section of tube and some patches. Make a hole 
 in the tube with a nail and with cement or " cementless " patch 
 repair this puncture, following the directions on the box. 
 
 1. Why is it necessary to clean the surface of the tube around 
 the puncture with gasoline? 
 
 2. Why is it customary to roughen the surface with sandpaper? 
 
 3. Could all punctures be repaired in this way? 
 
TIRES 
 
 117 
 
 4. What advantage has this method of repairing over vulcaniz- 
 
 ing? 
 
 5. Does this method make the repair permanent? 
 
 Fig. 51. — Five-minute vulcEuiizmg set for inner tubes. 
 
 C. Vulcanizing. Repair another puncture by vulcanizing, using 
 a small vulcanizer and the prepared patches. 
 
 The directions of the manufacturer should be followed expUcitly, 
 and in addition it may be necessary to direct a current of air from 
 the tire pump on the inflammable cardboard after you have set 
 fire to it. Otherwise it may burn very slowly or possibly go out. 
 
 6. Is this method of vulcanizing used by the expert repairman 
 in repairing a blow-out? 
 
 7. What is the difference between a puncture and a blow-out? 
 
 8. Does this method of vulcanizing make a permanent repair? 
 
 9. If the outer cover or casing bursts on the road, what can be 
 done? 
 
 f^^=^ ^ ^ 
 
 Fig. 52. — Proper method of folding inner tube. 
 
 D. Care of Tires. 
 
 10. Name at least six causes that lead to tire deterioration. 
 
 11. What precaution should be taken in regard to tires when 
 storing a car for the winter? 
 
Ii8 AUTOMOBILE LABORATORY MANUAL 
 
 12. Why is it essential to have the tire properly inflated at all 
 times? 
 
 13. Name some of the enemies of rubber. 
 
 14. State some important points in caring for tires. See The 
 Gasoline Automobile. 
 
 49. TIRES— C 
 
 Removing a Split-band Demountable Rim 
 
 MATERIALS. Laboratory automobile; wheel with split-band demountable 
 rim. 
 
 (a) Remove one of the rear tires from the laboratory automobile 
 by unscrewing the lugs which hold the detachable rim in place. 
 Place the lugs on the running board of the car. (Why?) Roll 
 the tire to a place where you have room to work on it. Deflate 
 it by removing valve core or plunger. 
 
 (6) This rim is known as a " split " rim. In order to prevent it 
 from opening a lock, or metal tab is riveted on the rim at the split. 
 The rim is locked when this tab is in the longitudinal position and 
 unlocked when it is in the transverse position. 
 
 (f) By means of a hammer unlock the rim and, with a rim 
 compressor, contract the rim. In doing this place one claw of the 
 tool diametrically opposite the split and the other claw close to the 
 split. 
 
 (d) Now remove the tire from the rim, being careful not to injure 
 the valve. If the casing should be rusted on, use one of the ordinary 
 tire tools to loosen it. Remove the flap and inner tube from the 
 casing and inspect the casing carefully for any defects. 
 
 (e) Carefully put the inner tube back into the casing and replace 
 it on the rim, performing the operations in the reverse order of 
 that given above. Do not forget to insert the flap and be sure 
 that it fits properly to avoid a pinched tube. Pump up the tire 
 
TIRES 
 
 119 
 
 before putting it back on the wheel. When it has been pumped 
 to the proper pressure replace it on the wheel. Set all lugs and 
 screws properly. Have the instructor inspect your work at this 
 point. 
 
 1 . What is the full name for this type of rim? 
 
 2. Describe the construction of two other kinds of demountabk 
 rims. 
 
 Fig. 53. — Operations in the removal of split-band type of rim from tire. 
 
 3. State the advantages of such rims? 
 
 4. What precaution should be taken when inflating the tire 
 after it has been mounted? 
 
 5. What is the function of a flap? 
 
 6. Is there any advantage in changing the casmgs of tires from 
 front to rear after they have been used for some time? 
 
 7. To what extent do " non-skid " casings prevent skidding? 
 
I20 AUTOMOBILE LABORATORY MANUAL 
 
 8. Is a " non-skid " casing of any value when used on front 
 wheels? 
 
 9. What is the best " non skid " device? What rules should be 
 observed in its use? 
 
 SO. CARBURETORS— C 
 Carburetor Adjustments 
 
 MATERIALS. Carburetors of various types, sectional carburetors. 
 
 When a carburetor is properly adjusted the mixture burns in the 
 cylinder with a colorless or bluish flame. If it is very rich it burns 
 with a yellow or smoky flame and tends to deposit carbon on spark 
 plugs, cylinders, and pistons. If it is too lean the engine will show 
 loss of power or " back fire " into the carburetor. For economical 
 use of fuel the carburetor may be adjusted to supply a sUghtly lean 
 mixture. 
 
 It is a common practice to begin the adjustment of a simple 
 carburetor by decreasing the supply of gasoline until, in pulling a 
 hill, the exploding mixture " backfires " into the carburetor as the 
 engine, under load, decreases its speed. Then the proportion of 
 gasoline is increased by very gradual steps until the engine pulls 
 the hill without " back firing." Great care must be observed to 
 avoid making the mixture too rich or richer than is necessary for 
 economical operation. The mixture may be richer than necessary 
 and yet show no visible evidence of richness. 
 
 The more comphcated carburetors with compensating air and 
 gasoline valves require special adjustments for the different speeds, 
 low, intermediate, and high, and the adjustment of these carbu- 
 retors should be taken up separately. 
 
 I. A very lean mixture burns slowly. Explain how this some- 
 times results in an explosion in the carburetor (back firing) when 
 the engine runs slowly. 
 
CARBURETORS 121 
 
 2. If the mixture is slightly lean, why does opening the throttle 
 suddenly sometimes cause " back firing " into the carburetor? 
 
 3. What sometimes causes " back firing " into the carburetor 
 in going up a steep hill just before shifting gears? 
 
 4. If the engine should " back fire " and ignite the gasohne 
 in the carburetor, what should be done immediately to avoid 
 burning up the car? 
 
 5. AVhat are some means of obtaining rich mixtures for starting? 
 
 6. If a priming cup is opened at the time of explosion, what 
 should be the color of the flame which shoots out? 
 
 7. In using low-grade gasoline, how does applying heat to the 
 carburetor and to the intake manifold aid carburetion? 
 
 8. Why does an engine run better when it is warmed up? 
 
 9. What kind of mixture produces a large percentage of the 
 deadly gas — carbon monoxide? 
 
 10. If the exhaust does not smoke at low speed and does smoke 
 at high speed, what adjustment is needed? 
 
 ir. What sometimes causes an engine to smoke badly at the 
 time of starting? 
 
 12. What would be the effect of a leak in the manifold at some 
 point between the carburetor and the cylinder? Old engines some- 
 times leak around the intake-valve stems. 
 
 13. If the engine runs for a short time and stops, then runs for a 
 short time and stops again, what may be the cause? 
 
 14. If a carburetor begins flooding slowly after the engine stops, 
 what may be the cause? 
 
 15. Carburetor adjustments should not be changed until other 
 possible troubles are carefully investigated. What other tests 
 should be made before changes are made on the carburetor adjust- 
 ment? 
 
122 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 SI. CARBURETORS— D 
 Carburetor Adjustments (Continued) 
 
 MATERIALS. Carburetors— Schebler Model E, Kingston Model E, and 
 HoUey Model G. 
 
 The many types of compensating devices and special adjustments 
 on the various makes of carburetors are all designed to keep the 
 proportions of the air and gasoline vapor constant with variations 
 in engine speed. The common adjustments are for low and high 
 
 /^/r ValveSpr'in^, 
 LsrfherAir Valve Di 
 
 Auxiliaru 
 Air Port— i^ 
 
 ThroH-le-^ 
 Lever 
 
 Throffh 
 Disc--.^. 
 
 Lock Spring 
 •' rLock Nu-h 
 
 .Air Valve 
 
 Floai Valve Cap 
 
 ■Ouflef 
 
 -Floaf Valve 
 
 Union Nuf- 
 
 Union Nipple 
 
 Primary AirJhIef- 
 Air Bend 
 
 Gasoline Adjusfinff 
 Needle Valve 
 
 Fig. S4. — Schebler Model E Carburetor. 
 
 speeds. If the carburetor contains a simple spray needle and a 
 simple auxiliary air valve, the spray needle is set for low-speed 
 adjustment and the auxiliary air valve is set to open at higher 
 speeds and supply the increased amoimt of air necessary to keep 
 the mixture properly balanced, 
 
CARBURETORS 
 
 123 
 
 A. The Schebler Model E. Use sectional carburetor, Schebler 
 Model E, manufacturer's circular, or illustration in Motor Vehicles. 
 
 1. Is this carburetor design concentric or eccentric? 
 
 2. By what type of adjustment is the gasoline controlled? 
 
 3. Where does the air for the low-speed adjustment enter the 
 carburetor? 
 
 4. Where does the additional air for the high-speed adjustment 
 enter this carburetor? 
 
 V/eiahkm Lever an 
 ihted me Throt fie Valve 
 
 ^Ib Ertffmelnfakc 
 
 Submei^d 
 fhzzle 
 
 Fig. 55. — Kingston Model E carburetor. 
 
 5. At what point does the mixture pass out of this carburetor? 
 
 6. What keeps the auxiUary air valve shut at low speeds? 
 
 7. What would be the effect upon the engine if the auxiliary 
 air-valve spring tension were too loose or if the auxiliary air valve 
 were held open at low speed? 
 
 8. Give directions for making the low-speed adjustment. See 
 Motor Vehicles. 
 
 9. Give directions for making the high-speed adjustment. 
 
 10. What is the function of the " air-valve adjusting screw " ? 
 
 11. What is the function of the " lock nut " and " lock sprmg " ? 
 
124 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 12. Explain the sequence of operations which result in opening 
 che auxiliary air valve when the throttle is opened. Is this valve 
 pulled open from the inside or pushed open from the outside? 
 
 B. The Kingston Model E. See Motor Vehicles. 
 
 13. Is this carburetor concentric or eccentric? 
 
 14. How does the position of the spray-needle in this instrument 
 differ from that in the Schebler Model E? 
 
 Fig. s6. — Holley Model G carburetor. 
 
 15. What is the function of the cup or puddle above the spray- 
 needle valve? This carburetor represents the " puddle type." 
 
 16. In this carburetor how is the auxiliary air for high speeds 
 supplied? 
 
 17. How many balls are used? Why are they placed at dif- 
 ferent depths? 
 
CARBURETORS 125 
 
 The Kingston Model L, similar in principle to the Kingston 
 Model E, was designed for and used for many years on Ford cars. 
 
 C. The Holley Models G and H. See The Gasoline Automobile. 
 These carburetors have no auxiliary air valve. 
 
 18. Wha't is the function of the low-speed tube in the Holley 
 models? 
 
 52. CARBURETORS— E 
 
 The Stromberg Plain Tube and the Zenith Model L 
 
 MATERIALS. Stromberg Plain Tube, and Zenith Model L carburetors; 
 instruction books and reference books. 
 
 A. The Stromberg Plain Tube. This is a plain-tube carbu- 
 retor. A number of the leading manufacturers are now making 
 " plam-tube " carburetors. In this type gasoline sprays into the 
 Venturi from small holes either in the walls of the Venturi, as in 
 the Stromberg, or in the nozzle housing, as in the Schebler. The 
 gasoline tube leading to the Venturi is " air-bled," having an 
 opening which admits air into the gasoline tube before it sprays 
 into the Venturi opening. With higher speeds and increased 
 suction a larger proportion of air enters the gasoline tube, thus 
 reducing the proportion of gasoline and keeping the mixture 
 properly balanced. With the reduced flow of gasoline at high 
 speeds no auxiliary air valve is necessary. 
 
 If a sectional model of the Stromberg plain-tube carburetor is 
 available, examine it. Use, as a reference. Motor Vehicles. 
 
 1. When the throttle is closed, as in idUng, what causes gasoline 
 to rise in the idling tube to the idling jet? 
 
 2. When the engine is idhng, why does gasoline not flow out by 
 the idling adjustment screw into the mixing chamber below the 
 throttle? 
 
126 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 3. In idling, what does flow by the idling adjustment screw? 
 
 4. If the idling adjustment screw were screwed in further, what 
 efiect would be produced upon the idling speed? 
 
 CARBURETOR FIANCE 
 
 LARGE VENTURI 
 
 .THROTTLE VALVE 
 
 IHE STROMBERC' 
 
 PLAIN TUBE 
 
 CARBURETOR 
 
 With Motof «t Rm 
 
 IDLE DESCHARCEJET 
 IDLE ADJUSTMENTT^EEDLE 
 HIGP SPEED ADJUSTMENT NEEDLE 
 
 FLDAT NEEDLE 
 
 MPCTURE CO^^TROL 
 VAlVE or CHOKER 
 
 STRAINER BODY' 
 
 DRAIN PLUC 
 
 Fig. 57. — Stromberg plain-tube carburetor. 
 
 5. In running at the higher speeds, how does air get into the 
 gasoline tube before it reaches the holes in the Venturi? 
 
 6. Under what conditions of operating the engine does air pass 
 from the bleeder tube down into the accelerating weU? 
 
 7. Where is the high-speed adjustment screw located? 
 
 8. Give directions for making the high-speed adjustment. 
 See Motor Vehicles. 
 
CARBURETORS 
 
 127 
 
 B. The Zenith Model L. See Motor Vehicles. 
 
 9. What difEcultyoccurs in the use of a single-nozzle carburetor 
 with varying speeds? 
 
 -i5upplt/Pipe 
 Fig. s8. — Constant-flow nozzle. 
 
 Supply Pipe* Supply Pipe 
 Fig. 59. — Zenith compound jet with engine standing still. 
 
 10. How does the Zenith correct for this trouble? 
 
 1 1 . Under what condition of engine speed is the larger proportion 
 of gasoline furnished by (a) the center nozzle, (6) the outer nozzle? 
 
128 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 12. What is meant by the expression "compensation" as 
 apphed to this carburetor? 
 
 Chamber ''^~\ ^JS**"^'"' '"H '' 
 
 iSupply PifK ' Supply Pips 
 Fig. 6o. — Zenith carburetor at low speed. 
 
 Chamber 
 
 Compensaftpr 
 
 y-"ri- 
 
 SuppiyPipe? ouppyPi'pe 
 Fig. 6i. — ^Zenith carburetor at high speed. 
 
 13. If the mixture is too lean at high speed which orifice should 
 be made larger? 
 
 14. Explain how gasoline is supplied in starting the engine. 
 
 15. Explain how gasoline is supplied for idling. 
 
CARBURETORS 
 
 129 
 
 S3. CARBURETORS— F 
 Reference Works Motor Vehicles and The Gasoline Automobile 
 
 MATERIALS. Carburetors o£ various types; manufacturers' instruction 
 sheets and reference books. 
 
 A. The Rayfield Model G. This carburetor has three air inlets 
 and two gasoline inlets. One of the air inlets is a constant opening 
 
 ICONSTANT AlRl 
 K\OPENINC / 
 
 Fig. 62. — Section of Rayfield Model G carburetor. 
 
 in the side of the carburetor leading directly to the spray-nozzle; 
 another is the upper automatic air valve; and a third is a butterfly 
 valve (lower air valve) which is controlled by the upper automatic 
 air valve and which opens when the upper air valve opens. One 
 gasoline inlet is the spray-nozzle, the other the metering pin. 
 
 Two adjustments are provided, high speed and low speed. Both 
 adjustments are on the spray-nozzle. The low-speed adjustment 
 sets the spray-nozzle as in any simple carburetor. The throttle 
 mechanism connects with the spray-nozzle pin, causing the spray- 
 
130 AUTOMOBILE LABORATORY MANUAL 
 
 nozzle to open wider as the throttle opens for high speed. This 
 mechanism contains the high-speed adjustment screw. 
 
 1 . For what speed does the carburetor depend chiefly upon the 
 constant air opening? 
 
 2. For what speed does the carburetor depend chiefly upon the 
 upper and the lower air valves? 
 
 3. What causes the metering-pin nozzle to open and supply 
 gasoline? 
 
 4. What keeps the upper automatic air valve closed at low 
 speed? 
 
 5. What opens the lower air valve? 
 
 6. What is the function of a dash-pot piston on an air valve? 
 
 7. How is this carburetor equipped for warming the mixture? 
 
 8. Explain the purpose and operation of the dash control on the 
 Rayfield. 
 
 9. Give directions "f or making the high-speed adjustipent on the 
 Rayfield. 
 
 B. The Marvel — Buick. This carburetor contains a spray 
 needle, an auxiliary air valve, and a high-speed nozzle. 
 
 10. What type of auxiliary air valve has this carburetor? 
 
 11. Explain the operation of the high-speed nozzle. 
 
 C. The Tillotson— Overland. 
 
 12. Explain briefly the regulation of the air supply in the Til- 
 lotson. 
 
 D. The Packard. 
 
 13. Does this carburetor contain a spray needle? 
 
 14. How is compensation provided for in this carburetor? 
 
 15. What provision is made for keeping the mixture warm? 
 
CARBURETORS 
 
 131 
 
 E. The Pierce-Arrow. 
 
 16. State {a) t3qDe of float chamber, (6) type of spray-nozzle, 
 (c) type of auxiliary air inlet. 
 
 F. The Cadillac. 
 
 17. State the function of (a) the " gas saver," {b) the throttle 
 pump, (c) the automatic throttle. 
 
 'hroftle /ever 
 
 Hot a/rjacket 
 
 M/xmL 
 
 Hot air cfamper 
 
 Air ai^'usting 
 
 •<,~A/r intake 
 Cfioke damper 
 
 Hot ajr Jacket' 
 Fig. 63. — ^The Marvel Model E carburetor. 
 
 G. The Stewart. 
 
 18. State the function of (a) the metering pin, (6) the valve A. 
 
 E. The Hudson. 
 
 19. What causes the piston to rise? 
 
 20. What controls the size of opening at the spray-nozzle? 
 
132 AUTOMOBILE LABORATORY MANUAL 
 
 S4. FUEL FEED SYSTEMS 
 
 MATERIALS. Ford chassis with tank and feed pipe; laboratory auto- 
 mobile with fuel system attached; sectional demonstration model of the 
 Stewart Vacuum Tank, or diagrams; manufacturers' circulars. 
 
 A. Gravity Feed Systems. See textbooks. 
 
 1. What is the meaning of the expression " Gravity Feed 
 System " ? Name a make of automobile which uses it. 
 
 2. When the gravity system is used, in what relative position 
 must the fuel tank be located with regard to the level of the float 
 chamber of the carburetor? State two common locations for the 
 fuel tank. 
 
 3. Examine the fuel tank on a typical automobile. State the 
 function of: (a) the tank cover, (b) the shutoff valve, (c) sediment 
 cup and drain plug. 
 
 4. What is the advantage of partitions in the fuel tank? 
 
 5. Should a fuel tank be closed air tight? Explain. 
 
 6. State the purpose of the carburetor float needle. What 
 carburetor trouble results from its not seating properly? 
 
 7. How is the gasoline shut off at the Ford fuel tank? 
 
 8. State two advantages in locating the fuel tank in the cowl. 
 
 B. Pressure Feed System. Many cars are now being con- 
 structed with fuel tanks attached to the rear end of the frame at a 
 point lower than the level of the carburetor float-chamber. In this 
 arrangement it is necessary to use either a pressure system or a 
 vacuum system for raising the fuel to the carburetor. The sim- 
 plest form of pressure system provides for pumping air into the 
 fuel tank above the gasoline, forcing the gasoline out through a 
 pipe in the bottom of the tank to the carburetor. For this purpose 
 an air pump may be operated by the engine, the hand pump being 
 used only for starting. 
 
FUEL FEED SYSTEMS 
 
 ^33 
 
 g. What advantage is obtained with this system in regard to 
 feed as compared with the gravity system? 
 
 10. State some other advantages in placing the fuel tank at the 
 rear of the frame. 
 
 11. What is the purpose of a safety valve in this system? 
 
134 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 12. State some sources of trouble in a pressure system. 
 
 C. The Stewart Vacuum System. In this system the gasoline 
 
 is drawn from the tank at the rear, by suction, obtained from the 
 intake manifold of the engine. The gasoline is drawn into a some- 
 what compHcated " vacuum tank " which is placed on the engine 
 
FUEL FEED SYSTEMS 
 
 I3S 
 
 side of the dash and from which the gasoline flows by gravity to 
 the carburetor. If a sectional model of this tank is available 
 
 Intake Manifold 
 
 Vacuum Tank 
 
 Fig, 66. — Vacuum system of gasoline supply. 
 Air Vent >f [W 
 
 Float L 
 
 To Carburetor 
 Fig. 67. — Stewart vacuum tank. 
 
 examine it carefully. Read the description of the Stewart Vacuum 
 Tank in The Gasoline Automobile and in Motor Vehicles. 
 
136 AUTOMOBILE LABORATORY MANUAL 
 
 13. What causes a condition of suction or a partial vacuum in 
 the pipe leading to the intake manifold? 
 
 14. What causes the valve between the upper chamber and the 
 intake manifold pipe to open? What causes it to close? 
 
 15. What causes the "flapper valve " between the upper and 
 the lower chambers to open? What causes it to close? 
 
 16. If this system does not feed properly, what are the probable 
 causes? See Motor Vehicles. 
 
 55. VALVE TIMING— FORD ENGINE 
 MATERIALS. Ford engine, ruler, and piece of chalk. 
 
 A. Read the discussion of valve timing in the Model T Ford 
 Car. The timing of the Ford valves is given in terms of the dis- 
 tance which the piston moves instead of in degrees as is com- 
 monly done with gas engines. 
 
 1. The opening and the closing of the inlet and the exhaust 
 valves is usually given as a certain number of degrees before or 
 after top-center position or bottom-center position of the piston. 
 How many degrees constitute a complete circle? 
 
 2. The circumference of the Ford flywheel is 46.5 inches. 
 One inch on the outside of the flywheel, therefore, equals how many 
 degrees? 
 
 B. Time the inlet valves of cylinders No. 3 and 4 in degrees as 
 follows: Locate the inlet valve by its position in relation to the 
 intake manifold. When the piston reaches top-center place a 
 chalk mark on the flywheel at a point opposite a chalk mark on the 
 top coil of the generator. Now watch the inlet valve and slowly 
 move the flywheel beyond top-center until you first notice the 
 inlet valve beginning to open. 
 
FORD VALVE TIMING 
 
 137 
 
 3. Measure in inches on the flywheel how far the chalk mark 
 has moved past top-center and state this in degrees. This is the 
 opening time for the inlet valve. 
 
 4. When the piston reaches bottom-center of the intake stroke 
 make another chalk mark and measure how far past bottom- 
 Center the mark has moved when the inlet valve has finished 
 dosing. State in degrees the time of closing of the inlet valve. 
 
 C. Time the exhaust valves of the same cylinders in a similar 
 manner. When the exhaust valve begins to open make a chalk 
 mark on the flywheel. When the piston reaches bottom-center 
 measure the distance moved in inches. 
 
 Top Center 
 
 Boffom Center 
 Fio. 68. — Valve timing of the average engine. 
 
 5. State in degrees the time of opening of the exhaust valve. 
 
 6. Determine the time of closing of the exhaust valve on the 
 Ford. 
 
 7. How does this timing of the Ford compare with the timing 
 of the average automobile engine? See valve-timing diagram, 
 Fig. 68. Make a corresponding diagram for the Ford engine. 
 
 8. What clearance should exist between the valve stem and the 
 push rod? 
 
138 AUTOMOBILE LABORATORY MANUAL 
 
 9. How would too much clearance affect the timing? 
 
 10. If the clearance is too small, what trouble may result? 
 
 11. How must the large and small time gears mesh when the 
 valves are properly timed? 
 
 12. Explain the timing marks frequently found on engine fly- 
 wheels. See Dyke. 
 
 56. IGNITION TIMING 
 
 Checking the Ignition Timing on the Laboratory Engines 
 
 MATERIALS. One and one-half horsepower gas engine on truck; engine 
 of one of the standard automobiles with battery ignition; Ford engine. 
 
 With the spark lever retarded the spark in an engine cylinder 
 should occur at top-center at the end of the compression stroke. 
 As the engine increases in speed the spark should be advanced in 
 order to get the maximum power. Ignition timing involves the 
 setting of the ignition mechanisms of the timer, the distributor, 
 and the spark lever so that when the spark lever is in the retarded 
 position the spark occurs at top-center of the compression stroke 
 and when the spark lever is advanced the spark occurs before the 
 piston reaches top-center of compression. 
 
 A. Laboratory Gas Engine. 
 
 1. Has this engine any device for advancing or retarding the 
 spark? 
 
 2. At what time with respect to top-center of the compression 
 stroke does ignition occur? 
 
 3. How may the ignition time of this engine be adjusted? 
 
 B. Automobile Engine. Check the ignition timing of this 
 engine. Read Motor Vehicles and The Gasoline Automobile on 
 
IGNITION TIMING 
 
 139 
 
 Ignition Timing. Open all priming cocks except on cylinder 
 No. I and place the spark lever in the extreme retarded position. 
 Examine the flywheel to see if it contains timing marks. See 
 Dyke. These marks may be used to determine the top-center of 
 cylinders No. i and No. 4. Top-center position in some engines 
 may be determined by removing a spark plug and placing a stick 
 into the spark plug opening against the top of the piston. When 
 the stick reaches the highest point as the engine is turned over the 
 piston is on top-center. 
 
 4. Why should the spark lever be in the retarded position when 
 the engine is timed? 
 
 5. In timing the engine, when should the contact points of the 
 timer separate? 
 
 6. If the contact points of the timer should not separate at the 
 proper time, what adjustment might be necessary? 
 
 7. What is the danger in cranking an engine by hand when the 
 spark is advanced? 
 
 8. What troubles occur when an engine is operated with spark 
 too far advanced? See Dyke. 
 
 9. Through how many degrees does the mechanism usually 
 permit the spark to advance? 
 
 10. How does the timer mechanism provide for advancing the 
 spark? 
 
 11. How would you determine the firing order of the engine? 
 
 12. How could you determine the direction of rotation of the 
 distributor arm? 
 
 13. How does an automatic spark advance mechanism operate? 
 
 C. The Ford Engine. 
 
 14. How can top-center of cylinder No. i be determined without 
 removing the cylinder head? 
 
 IS- With spark retarded, in what position should the piston 
 of the Ford be when the spark occurs? 
 
140 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 i6. What should be the position of the timer roller when the 
 spark occurs in question 15? 
 
 17. Describe the Ford spark advance mechanism. 
 
 57. DIFFERENTIAL— A. BEVEL GEARS 
 The Differential Mechanism and the Final Gears 
 
 MATERIALS. Small Meccano toy model; large laboratory automobile 
 chassis, and reference books. 
 
 Examine the small model of a differential. Note that one wheel 
 may revolve while the other stands still, or one wheel may go 
 
 ^xk Drive Shoff 
 ^jyr'ive Shaft Pinion 
 
 KJ 
 
 Fig. 69. — Simplified illustration of the differential gears. 
 
 forward while the other revolves in the opposite direction. Let 
 one person hold one rear wheel of the laboratory automobile while 
 the other turns the opposite wheel. Note that the differential 
 permits both wheels to revolve in the same direction either at the 
 same rate or at different rates. 
 
 1. State why a differential is needed in the operation of an 
 automobile. See Motor Vehicles. 
 
 2. In what position on the automobile is the differential usually 
 located? 
 
DIFFERENTIAL 
 
 141 
 
 3. Name one other position where it is sometimes located. See 
 Dyke. 
 
 4. Describe the position of the following parts of a bevel gear 
 differential mechanism: (a) differential housing, (6) drive-shaft 
 
 p-r^ 
 
 AXLE SMFT 
 
 D/FF£RENT/AL CASE 
 
 FtG. 70. — Differential gears, 
 
 pinion, (c) ring gear or driving gear, {3) spider gears, (e) axle-shaft 
 gears. 
 
 5. Make a diagram showing the parts mentioned in No. 4 
 and label the parts. 
 
 6. Explain the purpose or function of each part mentioned in 
 No. 4. 
 
142 AUTOMOBILE LABORATORY MANUAL 
 
 7. In the laboratory automobile differential mechanism how- 
 many axle shaft gears are used? How many spider gears? 
 
 8. Does the propeller shaft move if one wheel goes forward and 
 the other backward at the same rate? Explain. 
 
 9. If one wheel stands still and the other goes forward must the 
 propeller shaft move? 
 
 10. If both wheels go forward, but at different rates, must the 
 propeller shaft move? 
 
 11. If the automobile is moving straight ahead do the spider 
 gears revolve on their respective bearings? Explain. 
 
 12. Distinguish between the following types of final drive: 
 (a) bevel, (b) spiral bevel gear, (c) worm gear. See The Gasoline 
 Automobile. 
 
 13. For what reason is the spiral bevel gear preferable to the 
 simple bevel gear? The spiral type is more expensive. 
 
 14. To what kind of service is the worm gear well adapted? 
 
 58. DIFFERENTIAL— B 
 Disassembling the Ford Rear Axle 
 
 MATERIALS. Ford rear axle mounted on a stand; tools; reference books. 
 
 For information in regard to disassembling the Ford rear axle 
 and differential read the Ford Manual. Follow the instructions 
 carefully. Note the order in which the various parts are removed. 
 Place all parts in order on newspapers. Proceed slowly. When 
 fully disassembled have your work approved by the instructor. 
 
 Caution. Do not use a hammer or attempt to force any part of 
 the mechanism without first consulting the instructor. 
 
 For reference use Motor Vehicles and The Model T Ford Car. 
 
 I. Name three common types of differential. To which typ? 
 does the Ford belong? 
 
143 
 
 ilmii 
 
144 AUTOMOBILE LABORATORY MANUAL 
 
 2. Name the parts of a Ford differential. 
 
 3. What is meant by differential gear reduction? 
 
 4. What is the differential gear ratio of the Ford? Count the 
 number of teeth on the propeller shaft pinion and on the ring gear. 
 
 5. What kind of lubricant should be used in the differential? 
 How often should the lubricant be renewed? 
 
 6. How is the lubricant put into the differential? How can it 
 be drawn off? See Ford Manual. 
 
 7. What type of bearings is found in the Ford rear axle? 
 
 8. Would the differential operate with only one spider gear? 
 Why does the Ford use three? 
 
 9. When one rear wheel is on firm ground and the other in a 
 mudhole, why is it sometimes difficult to move the car? 
 
 10. Explain as clearly as you can how the differential mechanism 
 produces an equal puU on each rear wheel when the car is running 
 on the road. 
 
 59. ALTERNATING CURRENTS 
 
 Note. This experiment should be preceded by the experiments on tlie 
 electric motor and the electric generator. 
 
 MATERIALS. Pocket compass; large steel file, t inch wide by 10 inches 
 long, magnetized; telephone magneto; battery voltmeter; electric bell; dry 
 cell. Two coils of insulated copper wire of 1,000 turns each. 
 
 A. Introductory Experiments. Connect two insulated wires 
 each 3 feet in length to the terminals of one of the coils. Place 
 the coil on the table in position so that it Hes with opening hori- 
 zontal. Set the pocket compass on the top of the coil. Place 
 the coil in such position that its opening stands east and west. 
 
 I. Touch the free ends of the two wires to the two terminals 
 of a dry cell. Does the needle on the coil remain parallel to the 
 wires of the coil? What position does it take while the dry cell 
 current is flowing through the coil? 
 
ALTERNATING CURRENTS 
 
 145 
 
 2. What effect is produced upon a coil by a current passing 
 through it? 
 
 3. What causes the compass needle to change its position when 
 a current passes through the coil? State the law which appUes 
 to the attraction and repulsion of magnetic poles. 
 
 4. How can you reverse the direction of current flow through 
 the coil? 
 
 Co// contBfn/n^ 
 WOO turns 
 
 J)ry ce// 
 
 Prom Good's "Laboratory Projects in Physics" Used 
 by permission of the Macmillan Company^ publishers 
 
 Fig. 72. — ^Apparatus and wiring for the study of alternating currents. 
 
 5. What effect has this upon the polarity of the coil? 
 
 6. When the current through the coil is reversed, how is the 
 position of the north pole of the compass affected? Observe 
 closely. By reversing the flow of this dry cell current you produce 
 the effect of an alternating current upon the coil. An alternating 
 current flows first in one direction, then in the opposite direction. 
 
 7. How does an alternating current differ from a direct current 
 in its magnetic effect upon a coil through which it is flowing? 
 
146 AUTOMOBILE LABORATORY MANUAL 
 
 B. Alternating Currents Produced Mechanically. Remove the 
 dry cell and connect the two coils together by means of two 3-foot 
 wires. Pass a large permanent magnet (magnetized large steel 
 file) quickly into the coil just attached and observe the effect upon 
 the compass on the other coil. 
 
 8. What evidence have you that this magnetism cutting 
 through the turns of the coil generated an electric current? 
 
 9. Quickly pull the permanent magnet out of the coil. What 
 effect did this produce upon the other coil and upon the compass? 
 
 10. When a magnet approaches the opening of a coil the current 
 flows in one direction and when it recedes from the coil the current 
 flows in the opposite direction. How can you prove this? If the 
 coil of wire moves instead of the magnet, the same effect is pro- 
 duced. This illustrates the fundamental operation of all mechanic- 
 ally generated currents in dynamos and magnetos. 
 
 C. The Telephone Magneto. This is a low-tension alternating 
 current magneto generator. It is sometimes used in telephones 
 for the purpose of ringing the bell. Attach a small voltage electric 
 lamp to the binding posts of the telephone magneto and light it 
 by operatuig the magneto. 
 
 11. How is the magnetic field suppUed in this magneto? 
 
 Note that one end of the wire winding is attached to the armature 
 shaft which is insulated from the armature bearing. A spring 
 conductor touches the end of the armature shaft and connects it 
 by means of a wire to one of the binding posts of the magneto. 
 The other end of the winding is attached to the ring on the arma- 
 ture shaft. 
 
 12. What prevents the current from passing from the armature 
 shaft to the metal ring surrounding the shaft without passing 
 through the lamp? 
 
 13. What prevents the- current from passing from the metal 
 
MAGNETOS 147 
 
 spring which is in contact with the armature shaft to the metal 
 ring surrounding the shaft .without passing through the lamp? 
 
 14. Does this magneto deliver a direct or an alternating current? 
 
 15. What change would be necessary in order to make an alter- 
 nating-current magneto into a direct-current magneto? 
 
 16. Diagram the correct positions of the coil between the poles 
 of the field magnet to satisfy the following conditions: 
 
 (a) When the direction of current in the armature coil changes. 
 See Motor Vehicles, 
 ib) When the strength of the induced current is increasing. 
 (c) When the strength of the induced current is decreasing. 
 {d) When the voltage of the induced current is a maximum, 
 (e) When there is no current flowing. 
 
 60. IGNITION MAGNETOS— LOW-TENSION 
 
 The Remy Low-tension Magneto and the Ford Magneto 
 
 Note. Experiment 59, Alternating Currents, should precede this experiment. 
 
 MATERIALS. Automobile magneto, Ford ignition system (Ford demon- 
 stration car) ; dry cells; ring stands; wire. 
 
 Dry-cell current for automobile ignition purposes is expensive 
 and not always dependable. Magnetos for ignition purposes were 
 developed to ehminate these troubles. Magnetos may be divided 
 into two classes, — the armature coil type in which the coil of wire 
 is revolved between the poles of a permanent magnet, and the rotor 
 type in which the coil is stationary and the rotor causes the mag- 
 netic field to vary in the coil. Low-tension magnetos produce 
 low-voltage currents. High-tension magnetos produce high- 
 voltage currents. 
 
 A. The Remy Low-tension Magneto. Study the Remy or 
 some other low-tension magneto in the laboratory. This magneto 
 is of the rotor type. Read carefully The Gasoline Automobile or 
 
148 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 Motor Vehicles on the rotor t3^e of magneto. If but one winding 
 is used, the resulting voltage will be low, therefore it is caUed a 
 
 low-tension magneto. A high-tension magneto has both a primary 
 and a secondary winding. Examine, if possible, a cross-section of 
 a high-tension magneto. Note the primary and secondary 
 
MAGNETOS 149 
 
 windings. With a low-tension magneto an induction coil is 
 necessary for producing the high-tension current for ignition. 
 
 1. What is the function of the rotor arms in this type of 
 magneto? See Motor Vehicles or The Gasoline Automobile. 
 
 2. Of what material are the arms made? Why? 
 
 3. Does the coil in a rotor type of magneto revolve? Explain 
 how a current is induced in this coil. 
 
 4. In what position of the rotor arms does the maximum num- 
 ber of lines of magnetic force pass through the coil? Make a 
 diagram. See Motor Vehicles. 
 
 5. Explain how the direction of magnetic lines of force is 
 reversed in the coil. 
 
 B. The Ford Magneto. The Ford magneto generates an alter- 
 nating-current. Study the Ford ignition system on the demon- 
 stration car in the laboratory. Read Motor Vehicles and The 
 Gasoline Automobile on the Ford magneto. 
 
 6. To what type of magneto does the Ford magneto belong — 
 low-tension or high-tension? 
 
 7. How many coils does the Ford magneto have? Whpre are 
 they located? 
 
 8. How many magnets does the Ford magneto have? Where 
 are they located? What is their shape? 
 
 9. Diagram the magnetic field through two of the coils when a 
 north pole of one of the magnets is opposite one of the coils and the 
 south pole of the magnet is opposite an adjacent coil. See The 
 Gasoline Automobile. 
 
 10. What part of a revolution must the fljrwheel make before 
 the direction of the magnetic lines of force through the coils will 
 change? 
 
 11. How does this changing of direction of the magnetic lines 
 of force affect the current induced in the coils? 
 
 12. How many times is the direction of the current reversed 
 while the flywheel makes one revolution? 
 
ISO 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 13. What use does the Ford car make of the current which is 
 generated by the magneto? 
 
 Magneto Coil Spoot- 
 
 Copper Wire 
 
 End of Ribbon 
 Grounded Here 
 
 To Coil 
 
 Fig, 74. — ^The Ford magneto. 
 
 14. Is it possible to use this current for charging a storage 
 battery? Why? 
 
 Note. For the High-tension magneto see Ignition Systems — F. 
 
AUTOMOBILE ELECTRIC CIRCUITS 151 
 
 61. AUTOMOBILE ELECTRIC CIRCUITS— C 
 The Starting, Charging, Ignition, and Lighting Circuits 
 
 MATERIALS. Electric generator used in the experiment on the electric 
 generator; electric motor; storage battery; battery ammeter; two switches; 
 induction coil; spark plug; telegraph sounder adapted to show the principle 
 of the automatic cut-out; a standard type of automobile cut-out; wires. 
 
 With the apparatus found in the cabinet wire up on a table a 
 complete automobile wiring system, showing the operation of the 
 charging system, the starting system, the ignition system, and the 
 lighting system, including the automatic cut-out in the charging 
 system, the ammeter, the storage battery, the ignition switch, and 
 the starting switch. Have the work approved by the instructor 
 before the apparatus is taken down. 
 
 1. Make a copy of the diagram of the typical automobile wiring 
 ■ system. See Fig. 27. What is meant by the so-called single- wire 
 
 system? What are some of the advantages of the single-wire 
 system? See Motor Vehicles. 
 
 A. The Starting Circuit. 
 
 2. Does the current which operates the starting motor pass 
 through the ammeter? Explain. 
 
 3. With a 6-volt storage battery about how many amperes 
 are required to turn over an ordinary automobile engine? 
 
 4. What effect would this amount of current have upon an 
 ordinary instrument board ammeter? 
 
 5. Name four uses for electric current which is registered on 
 the ammeter at the instrument board. 
 
 B. The Charging Circuit. 
 
 6. At about what speed of the car does the generator begin to 
 charge the storage battery? 
 
IS2 AUTOMOBILE LABORATORY MANUAL 
 
 7. What electrical mechanism connected with the generator 
 prevents the storage-battery current from flowing through the 
 generator when the generator is standing still or running slowly? 
 
 8. Why should the generator not be connected with the storage 
 battery at low speed? 
 
 C. The Ignition Circuits. 
 
 9. From what source does the ignition current come when the 
 engine is being started? 
 
 10. From what source does the ignition current come when the 
 engine is running at speeds greater than about ten miles per hour? 
 
 11. What causes the direction of the current to change at higher 
 speeds? 
 
 12. On the automobile, what shows that this change takes place? 
 
 13. Name the parts of the apparatus through which the ignition 
 current flows at low speed. 
 
 14. Name the parts of the apparatus through which the ignition 
 current flows at high speed. 
 
 15. State the advantages of an ammeter in the electrical system. 
 
 16. What part of the ignition circuit of an automobile causes the 
 ignition current to flow intermittently? 
 
 17. Does the ammeter register current used for ignition when the 
 engine is running at high speed? Explain. 
 
 D. The Lighting Circuits. 
 
 18. With respect to resistance, why does parallel connection of 
 lamps cause them to burn " bright " ? 
 
 19. Witli respect to resistance, why does series connection cause 
 the lamps to burn " dim " ? 
 
 20. What is the reason for operating the tail light and the instru- 
 ment board light in series? 
 
 E. Fuses. 
 
 21. Why are fuses used in electrical circuits? Locate the fuses 
 in one make of automobile. 
 
AUTOMOBILE ELECTRIC GENERATORS 153 
 
 62. AUTOMOBILE ELECTRIC GENERATORS 
 The Generator, the Cut-out and Current Regulation 
 
 MATERIALS. Laboratory automobile with electric starting and lighting 
 system; reference books. 
 
 Note. Review Experiment 18 — The Electric Generator. 
 
 When a storage battery is used for ignition, starting and lighting 
 an electric generator supplies current for charging the storage 
 battery. See Experiment 22. The generator is usually operated 
 from the crankshaft either by gear or chain drive or from the 
 pump shaft. Since the engine runs at variable speeds the generator 
 and the charging circuit must be so designed that, at medium 
 speeds, the generator supplies a proper amount of current for the 
 battery. At low speed the generator circuit must be entirely broken 
 and at high speeds the current must not be excessive. This 
 requires an automatic cut-out to break the circuit when the engine 
 is idle or running slowly and a special type of winding in the 
 generator coils or other regulating device to prevent too great a 
 current at high speeds. Read Motor Vehicles and The Gasoline 
 Automobile. 
 
 1. How does a single-unit starting and lighting system differ 
 from a two-unit system? 
 
 2. Make a simple diagram of a lighting system without cut-out. 
 See Motor Vehicles. Write in full the names of each part of the 
 system. 
 
 3. Make a simple diagram of a starting and lighting system 
 mcluding the cut-out. See Motor Vehicles. Name all parts. 
 
 A. The Automatic Cut-out. 
 
 4. State the function of a cut-out in a charging circuit. 
 
 5. Which of the two coils of the cut-out causes the contact 
 
154 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 SHUNT WOUND DYNAMO 
 
 (B) SERIES WOUND DYNAMO 
 
 (C) CUMULATIVE COMPOUND WOUND 
 DYNAMO WITH SHORT SHUNT 
 
 (D) CUMULATIVE COMPOUND WOUND 
 DYNAMO WITH LONS SHUNT 
 
 (C) DIFFERENTIAL COMPOUKD WOUND 
 DYNAMO WITH SHORT SHUNT 
 
 (F) DIFFERENTIAL COMPOUND WOUND! 
 DYNAMO WITH L0N6 SHUNT 
 
 Fig. 75. — Tyijes of dynamo field windings. 
 
AUTOMOBILE ELECTRIC GENERATORS 
 
 ISS 
 
 points to close? What causes the contact points to open when the 
 magnetism in the core disappears? 
 
 6. To what are the wires of the coil which closes the cut-out 
 attached? When does it close the cut-out? 
 
 7. The second coil on *he cut-out core is part of what circuit? 
 8 How is this coil wound with respect to the winding of the 
 
 coil referred to in question 5? 
 
 REVERSE CURRENT CUT-OUT 
 
 V .....-.» SPRING 
 
 U6HTINS 
 S^rSTEM 
 
 CURRENT COIL 
 IHEAVY WINDING) 
 
 CUT-OUT POINTS __cg> 
 '(NeRnAU.T OPEN) I jfS' 
 
 StIUNT FIELO 
 
 wiNDins 
 
 LAMPS 
 
 — sa 
 
 Fig. 76. — ^Wiring diagram of a generator, cut-out and storage battery. The generated 
 current is regulated by reverse direction series field winding. Note also the 
 reverse current cut-out. 
 
 9. Does the magnetism of the one coil increase or oppose the 
 magnetism of the other? 
 
 10. How does the magnetism of one of the coils aid in causing 
 the contact points to break? Explain the conditions which cause 
 the contact points to break. 
 
 11. If a cut-out does not open when it should, what trouble may 
 result? 
 
 B. Third Brush Regulation of Generator Current. 
 
 discussion in The Gasoline Automobile. 
 
 Read this 
 
IS6 AUTOMOBILE LABORATORY MANUAL 
 
 12. What type of armature winding is commonly used foi: this 
 method of regulation? 
 
 13. Under what condition of speed are the lines of magnetic 
 force through an armature coil fairly evenly distributed? 
 
 14. Under what condition of speed are the lines of force through 
 the armature distorted? 
 
 15. To what regions of the field poles does this distortion shift 
 the lines of force? 
 
 16. What effect upon the field magnetism is caused by this 
 shift of the magnetic force away from that part of the armature 
 which produces the current for the field magnetism? 
 
 17. With respect to the direction of rotation of the generator 
 armature how should the third brush be moved in order to increase 
 the output of the generator? 
 
 C. Current Regulation. 
 
 18. Study the method of current regulation on the laboratory 
 automobile generator. Use reference books and write a report 
 on it. 
 
 63. AUTOMOBILE STARTING MOTORS 
 
 The Motor, Starter Drives, and Troubles 
 
 MATERIALS. Laboratory automobile with electric starting and lighting 
 system; reference books. 
 
 Automobile starting motors belonging to the two-unit systems 
 are similar in construction to other direct-current motors. They 
 are made with very heavy wires and heavy brushes for carrying 
 large amperages at low voltage for the short period required to 
 turn the engine over in starting. For reference use The Gasoline 
 Automobile. 
 
AUTOMOBILE STARTING MOTORS 
 
 1S7 
 
 A. The Starting Motor. 
 
 1. What is the usual voltage for operating a starting motor? 
 
 2. About what amperage with the usual voltage is required 
 to turn an automobile engine over? 
 
 3. How many watts and what horsepower does this represent? 
 (VoltsXamperes = watts) (746 watts = 1 horsepower). 
 
 4. What trouble may result from too frequent and prolonged 
 use of the starting motor? 
 
 5. Why is a series-wound motor more satisfactory for this 
 purpose than a shunt-wound motor? What is meant by starting 
 torque of a motor? 
 
 CONNECTION TO ARM. SH APT "OTOR^^^Mg 
 CONNECTION TO SCREW \ m^^B^^^Bf^^ 
 
 ■: «:Rewshaft-\ weicht\ \,j|SE^||HH 
 
 ' - STOP \ ' '\ .2iaS^MSS6K."'^M^^^^Bi 
 
 COLLAR \ ^jA«|ME^^SS»{^JrH^^^H 
 
 i 
 
 1 
 
 \ STARTING 
 SWITCH 
 
 T 
 
 H 
 
 . J™.v' 
 
 ARM- \^,^mS^SffmMffl^SBk^^^^^^ 
 
 W 
 
 _/^^ 
 
 
 ^j^ 
 
 ^^^ 
 
 .^^T^SP^SL starting ^^pi^ ---^ 
 
 MS^j^W'fS^- MOTOR CROUMDElT ■=■ g^ ■ 
 
 
 P 
 
 FLY WHE£l^^M|^£^|^^ ^V 
 
 ^^^Ptbattery I 
 
 ^~- -' j5__ -. . 
 
 
 ^1 
 
 Fig. 77. — ^Typical Bendix drive starting motor. 
 
 6. Examine the starting motor on the laboratory automobile. 
 State the number of (a) field poles, (b) brushes, (c) commutator 
 segments. 
 
 7. Give the principal characteristics of the North East one- 
 unit starter-generator. 
 
 8. Give the principal characteristics of the Delco one-unit 
 starter-generator. 
 
158 AUTOMOBILE LABORATORY MANUAL 
 
 B. Starter Drives. 
 
 9. Name three types of drives. 
 
 10. Describe (a) the Bendix drive, {b) the magnetic drive. 
 
 11. What is the usual gear reduction in starter drive mechan- 
 isms? 
 
 W'WDtNO ^1-™..,^ OIL CUP MOLOLR EHACKLJ MAGNtT 
 
 SHiniNG C5MMUTArOR 1 5I!IFT:n6 m;S!,et ftETU^N ItBfilNAL ti:Bf^l^^AL THROUGH 
 
 fiOD PINION COftt SPHIKt aUjHING NUTS- BOLTS 
 
 Fig. 78. — Parts of Westinghouse starting motor with electromagnetic pinion shift. 
 
 Fig. 79. — Westinghouse starting motor with automatic electromagnetic pinion shift. 
 
 C. Starting Troubles. See The Gasoline Automobile. 
 
 12. State possible troubles (a) at the battery terminals, (J) in 
 the starting circuit wires, (c) at the brushes, {d) at the switch, 
 (e) at the drive mechanism. 
 
IGNITION TROUBLES 159 
 
 64. IGNITION TROUBLES AND ADJUSTMENTS 
 
 Spark Plugs, Wires, Timer, Induction Coil, Distributor, Battery, 
 and Magneto 
 
 MATERIALS. Automobile engine; tools; reference books. 
 
 Remove the wires from the spark plugs of the engine. With an 
 end wrench remove the spark plugs and examine them. 
 
 A. Sparkplugs. 
 
 1. Is there any deposit on the spark-plug porcelain and points? 
 Name two sources from which this deposit may come. 
 
 2. How should spark plugs be cleaned? 
 
 3. Adjust the spark gap. How far apart should the points be? 
 
 4. How does the distance between the terminals of the points 
 affect the spark? 
 
 Attach the wires to the plugs and lay them on the tops of the 
 cylinders in such position that you can see the spark points as the 
 engine is cranked. Turn on the ignition switch and observe the 
 sparks. 
 
 5 . In what sequence do the plugs fire? Consider the plug nearest 
 the radiator as No. i. In what sequence do the inlet valves open? 
 
 6. Does failure of a spark plug to fire when tested necessarily 
 imply that the spark plug is at fault? Explain. 
 
 7. If one of four engine spark plugs is not firing, how could 
 you find out which one it is? Give three methods. 
 
 B. Wires. 
 
 8. If the wires leading to the plugs were not connected to the 
 proper plugs, how would you proceed to check up the wiring? 
 
 9. What is meant by a short-circuited primary wire? a short- 
 circuited secondary wire? 
 
i6o AUTOMOBILE LABORATORY MANUAL 
 
 10. Could an engine run (a) if the wire leading to one of the 
 plugs were disconnected? (i) if one of the wires of the primary 
 circuit were broken? 
 
 C. The Timer. 
 
 11. What trouble would probably result if the timer became 
 dirty or if the breaker points were improperly adjusted? 
 
 12. What are the symptoms of improper adjustment of the 
 spark advance mechanism? 
 
 D. The Induction Coil. 
 
 13. If the secondary wires of an induction coil were short- 
 circuited, what would probably be the effect upon the operation 
 of the spark plug? 
 
 14. What possible troubles may occur in the use of vibrating 
 induction coils? 
 
 15. How might a condenser cause trouble? 
 
 E. The Distributor. 
 
 16. If the distributor became dirty or cracked, what trouble 
 might result? 
 
 F. The Battery. 
 
 17. If battery terminals became corroded, what might be the 
 result? 
 
 18. State one other comimon battery trouble. 
 
 G. The Magneto. 
 
 19. What trouble at the spark plugs might result from weak 
 magnets in a magneto? 
 
 20. What would be the probable effect of excessive moisture 
 upon a magneto? 
 
 21. What trouble in a magneto might be caused by dirt or excess 
 of oH? 
 
ENGINE PARTS i6i 
 
 65. ENGINE MECHANICAL PARTS AND BEARINGS 
 The Crankshaft, the Camshaft, and the Connecting Rods 
 
 MATERIALS. Laboratory engines and reference books. 
 
 To avoid excessive wear and unnecessary noise it is very impor- 
 tant that all bearings should be kept properly adjusted and lubri- 
 cated. If bearings become loose, the friction surfaces wear away 
 more rapidly, resulting in the weakening of essential mechanical 
 parts, disagreeable engine knocks, and expensive repairs. 
 
 For reference work use Dyke. 
 
 A. The Crankshaft and the Main Bearings. 
 
 1. State the function of the crankshaft in an automobile. 
 
 2. What is the usual number of main bearings supporting the 
 crankshaft in (a) a four-cylinder engine, (i) a six-cylinder engine? 
 
 3. To what parts of the engine are the main bearings attached? 
 
 4. What trouble would result if only the end bearings were 
 used for supporting the crankshaft? 
 
 5. Why are bushings used in bearings ? Of what materials 
 are they made? 
 
 6. State the function of (a) the cap of a crankshaft or connect- 
 ing-rod bearing, (6) shims. See Fig. 80. 
 
 7. Name two systems of lubrication by which oil may be 
 supplied to the main bearings. 
 
 8. If a bearing becomes worn and loose what first adjustment 
 may be necessary? What part may need renewal after -further 
 wear? 
 
 9. What is a counterbalanced crankshaft and what are its 
 advantages? 
 
i62 AUTOMOBILE LABORATORY MANUAL 
 
 B. Connecting Rod and Bearings. 
 
 10. Describe the construction of the bearing which fastens the 
 connecting rod to the crankshaft. 
 
 11. Describe the construction of the wrist-pin bearing. 
 
 12. How does the Ford wrist-pin bearing differ from that of 
 most other cars? 
 
 13. State two methods of lubricating wrist pins and crank pins. 
 
 C. The Camshaft. 
 
 14. In comparison with the speed of the crankshaft at what 
 speed does the camshaft revolve and how is it operated? 
 
 15. Name the parts of a camshaft which involve friction and 
 which are subject to wear. 
 
 16. A cam is a device for changing a rotary motion into what 
 kind of motion? 
 
 17. Why does a cam which operates an exhaust valve usually 
 have a broader nose than one which operates an intake valve? 
 
 18. What part of the valve mechanism does the cam push 
 against? 
 
 19. In an old engine when cams become badly worn what effect 
 is produced upon the valve operation? 
 
 20. What part of the lubrication system in some engines is 
 operated by the camshaft? 
 
 21. Explain how the time gears and the camshaft are lubricated 
 in one make of engine. 
 
 66. ENGINE KNOCKS 
 
 Knocks — Their Causes, Location, and Remedies 
 
 There are probably no more puzzUng disorders for the average 
 automobile owner than the varied types of engine knocks. In 
 fact, with some of the more difficult knocks it frequently happens 
 
ENGINE KNOCKS 163 
 
 that a group of experienced repairmen will disagree among them- 
 selves as to the cause of the trouble. It is a time-consuming 
 and an expensive procedure to begin by dismantling an engine 
 before making a systematic diagnosis in order to determine the 
 location and cause of a specific knock. A knock is usually a 
 signal that some correction or adjustment is needed and it should 
 not be ignored. Before looking for any mechanical trouble other 
 possible causes of knocking should be carefully checked, such as 
 (0) pre-ignition, (b) spark too far advanced, (c) defective carbure- 
 tion, {d) incorrect valve clearance. 
 For reference use Dyke. 
 
 A. Explosion Knocks Caused by Firing Out of Time. 
 
 1. Explain how a knock is produced when a car goes up a steep 
 hill with the spark too far advanced. 
 
 2. What is meant by pre-ignition? Why does pre-ignition 
 cause a knock? 
 
 3. How might operating with a mixture that is too rich cause 
 pre-ignition? 
 
 4. How could too much oil cause pre-ignition? How might 
 an overheated engine cause pre-ignition? 
 
 5. Do pre-ignition knocks occur at all times? When do they 
 occur? 
 
 6. How might the kind of lean mixture which causes an 
 explosion in the carburetor also cause a slight knock? 
 
 7. How might an exhaust valve which does not close properly 
 cause a slight knock? 
 
 B. Eiiocks Caused by Loose Bearings and by Parts that Need 
 Adjustment. On accoimt of wear in old engines loud knocks are 
 common on crank main bearings, crank-pLn bearings, and wrist-pin 
 bearings. Occasionally in new engines knocks develop due to 
 lack of proper adjustment of bearings or parts. 
 
 8. What causes piston slap? 
 
164 AUTOMOBILE LABORATORY MANUAL 
 
 9. State a test for loose pistons. 
 
 10. How is an iron or steel rod sometimes used for locating 
 knocks ? 
 
 11. How does a connecting-rod bearing knock usually sound? 
 
 12. What is the best direct test for a loose wrist-pin bearing or 
 a loose crank-pin bearing? 
 
 13. What adjustment can usually be made on lower connecting- 
 rod bearings? 
 
 14. A knock which sounds like a double pound in very rapid 
 succession should be located where? 
 
 15. How does a knock caused by pre-ignition or by having the 
 spark too far advanced sound as compared with a crankshaft or a 
 connecting-rod knock? 
 
 16. If a clicking noise occurs, where would you expect to locate 
 it? What is usually the cause? 
 
 17. State a simple test for noisy valves. 
 
 18. How are noisy valves usually remedied? 
 
 Other occasional causes of knocks and noises are: a loose fly- 
 wheel, loose cylinder nuts, poorly adjusted camshaft and time 
 gears, or more remote parts of the car that may be loose and free to 
 vibrate. 
 
 67. PISTONS AND CYLINDERS 
 
 MATERIALS. Automobile engine block; box containing pistons; rings; 
 materials for manipulation. 
 
 In an automobile engine the pistons receive the expanding force 
 of the explosion in the combustion chamber, and by means of the 
 piston the energy of the exploding gases is transmitted to the 
 connecting rod and to the crankshaft for driving the car. Examine 
 a piston and connecting rod which have been removed from one 
 of the laboratory engines. (The Ford.) 
 
PISTONS AND CYLINDERS 
 
 i6S 
 
 A, Pistons. For reference work, use Dyke; see Engine Parts. 
 
 1. Diagram (a) a piston in section, (b) a connecting rod, 
 (c) a lap-joint piston ring, (d) a butt-joint piston ring. 
 
 2. What reasons can you give for making a gas-engine piston 
 hollow? 
 
 CAP 
 
 WRIST 
 PIN 
 
 BEARING 
 
 Fig. 8o. — Piston, connecting rod and parts. 
 
 3. Is the force of the explosion exerted against the open end 
 or the closed end? 
 
 4. What is the purpose of piston clearance? 
 
 5. Explain the function of the piston rings? How many rings 
 are commonly used on each piston? 
 
 6. What is the function of an oil groove on the piston? 
 
 7. In the more common types of automobile engines how do 
 the pistons receive their oU? 
 
1 66 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 8. How are new piston rings put on a piston? 
 
 9. Mention five causes of compression leakage due to defects 
 in piston rings. See Dyke — index. 
 
 '-^S! 
 
 10. What is the function of the wrist pin and of what metal is 
 it commonly made? 
 
PISTONS AND CYLINDERS 167 
 
 B. Manipulation. Read Dyke on the removal of piston rings. 
 
 (a) With the necessary tools as described in Dyke remove all 
 of the piston rings from one of the pistons. Special care should be 
 taken to avoid spreading the rings more than is necessary to insert 
 the thin metal strips. Carelessness in this respect may result in 
 either breaking the rings or bending them so that they fail to fit 
 properly. If you are in doubt as to the procedure inquire of the 
 instructor. When all rings are removed from one piston have the 
 work approved by the instructor. 
 
 (b) Read Dyke on " Fitting Rmgs to Pistons." Replace the 
 rings on the piston and show the piston to the instructor. 
 
 (c) Fit a piston, with rings attached, into an engine cylinder. 
 Have this job inspected, then remove the piston and place it in the 
 supply box as found at the beginning. 
 
 C. Cylinders. For reference read Dyke. 
 
 11. State the characteristics of a well-made cylinder. 
 
 12. State the advantages and disadvantages of T-head and 
 L-head engines. 
 
 13. Describe two types of cylinder construction other than the 
 T head and the L head. 
 
 14. What is meant by (o) stroke, (b) bore, (c) piston displace- 
 ment? 
 
 15. State the stroke and the bore of five well-known makes of 
 cars. See Dyke, " Specifications of Leading Cars." 
 
 68. ENGINE POWER 
 
 Calculating the Power of a Gas Engine 
 
 When a pound weight is Ufted vertically through a distance of i 
 foot, I foot-pound of work is done. The foot-pound is the unit 
 of work. When 50 pounds are lifted through a distance of i foot. 
 
l68 AUTOMOBILE LABORATORY MANUAL 
 
 50 foot-pounds of work are done. If 50 pounds are lifted through 
 10 feet, the work done is 500 foot-pounds. To find the foot- 
 pounds of work done in any mechanical operation multiply push 
 or pull in pounds by the distance in feet through which the thing 
 pushed or pulled is moved. 
 
 The power of an engine depends upon how much work it can do 
 per minute (per unit of time). If an engine is able to lift 33,000 
 pounds through a distance of i foot in one minute, that engine is 
 considered able to do work at the rate of i horsepower. The 
 same engine may Hft i pound through a distance of 33,000 feet, 
 etc. In general, if an engine does 33,000 foot-pounds of work 
 in a minute it is said to work at the rate of a horsepower. An 
 engine that does 66,000 foot-pounds of work in a minute is a 2- 
 horsepower engine, etc. 
 
 To find the horsepower of an engine find how many foot-pounds 
 of work it does per minute and divide this result by 33,000. 
 
 1. In going up a hill an automobile engine lifts a 3,000-pound 
 car through a vertical difference of level (vertical height of the 
 hill, not the slope) of 200 feet in one minute. Find how much work 
 is done and what horsepower is required to do this work in this 
 time. Disregard all friction. 
 
 2. Does friction increase or decrease the power required to do 
 an actual piece of work such as that in problem i. Mention three 
 sources of friction in this situation. 
 
 3. With a foot rule measure the diameter of the cylinder of the 
 laboratory four-stroke engine. Measure also the length of stroke 
 in nches (distance between the extreme outward and the extreme 
 inward position of the piston). Have these measurements 
 approved by the instructor before proceeding further. Calculate 
 the area of the face of the piston in square inches. Use two decimal 
 places only. 
 
 4. Assuming that the average pressure during the power stroke 
 is 90 pounds per square inch, calculate the average pressure on the 
 total face of the piston during the power stroke. 
 
MISCELLANEOUS PARTS 169 
 
 5. Ask the instructor for a speed indicator. Place it against 
 the engine crankshaft and determine the number of revolutions 
 per minute. (Run the engine at maximum speed.) 
 
 6. Calculate the work done in one power stroke. (Total pres- 
 sure in pounds on the piston times length of stroke in feet.) 
 
 7. In a four-stroke engine note that every fourth stroke is a 
 power stroke. How much work can this engine do per minute 
 when it is running at the rate of 500 revolutions per minute? 
 (Refer to question 6.) 
 
 8. Based on the above calculations, what horsepower has this 
 engine? (Work per minute divided by 33,000.) Assume that 
 on account of friction the engine delivers 75 per cent of the indicated 
 power. 
 
 9. What is the S. A. E. formula for calculating the horsepower 
 of a gas engine? See Motor Vehicles. 
 
 10. Calculate the horsepower of the engine used above by the 
 S. A. E. formula. This formula is based upon a piston speed of 
 1,000 feet per minute. How far does this piston move per revolu- 
 tion (out and back)? How far in feet does it move per minute? 
 If the piston speed of this engine is less than 1,000 feet per minute 
 the power will be in porportion to the piston speed. 
 
 11. Calculate the horsepower of the Ford engine by the S. A. E. 
 formula. 
 
 69. STEERING GEAR, MUFFLER, WHEELS, AND 
 BEARINGS 
 
 MATERI.'VLS. Laboratory automobiles and reference books. 
 
 A. Steering Gears. Read The Gasoline Automobile and 
 Motor Vehicles. 
 
 I. Why is the front axle of an automobile rigid as compared 
 with that of a horse-drawn vehicle? 
 
I70 
 
 AUTOMOBILE LABORATORY MANUAL 
 
 2. Describe the location of the following parts of the steering- 
 gear mechanism: (a) steering knuckle, (6) tie rod, (c) drag link, 
 {dj steering-lever arm, (e) steering-knuckle arm. See Fig. 31. 
 
 3. Distinguish between reversible and irreversible steering 
 gears. 
 
 4. What kind of steering gear has the Ford car — reversible or 
 irreversible? 
 
 Fig. 82. — ^Worm and wheel steering gear. 
 
 5. Name one other make of car with which you are familiar 
 and state whether the steering gear is reversible or irreversible. 
 
 6. Explain how camber makes the steering mechanism work 
 more easily. 
 
 7. How does a worm and wheel type of gear mechanism used in 
 some cars provide for adjusting in case of wear ? 
 
MISCELLANEOUS PARTS 171 
 
 B. MuflHers. 
 
 8. Diagram two commercial types of muflBer design. 
 
 9. Approximately what is the pressure of the expanding gas in 
 the cylinder when the exhaust valve opens? 
 
 10. How does a muffler aflEect engine power? 
 
 11. What are the characteristics of an efficient muffler? 
 
 12. What is the function of a cut-out placed on the exhaust 
 pipe? 
 
 C. Wheels. 
 
 13. State three kinds of strains that automobile wheels must 
 withstand. 
 
 14. Under what conditions of strain are wooden wheels most 
 likely to break? 
 
 15. What kind of wood is used for making wooden wheels? 
 
 16. Why are wheels dished? 
 
 17. What advantages over wooden wheels are claimed for wire 
 wheels? 
 
 18. What claims are offered in favor of pressed steel wheels ? 
 
 D. Bearings. 
 
 19. State three kinds of bearings in common use on automobiles. 
 
 20. What kind of bearings are commonly used for crankshaft 
 main bearings? Why? 
 
 21. Name three important parts of an automobile which usually 
 operate on roUer bearings. 
 
172 AUTOMOBILE LABORATORY MANUAL 
 
 70. CHASSIS ARRANGEMENT, FRAMES, AND SPRINGS 
 
 MATERIALS. Laboratory automobiles and reference books. 
 Read The Gasoline Automobile and Motor Vehicles. 
 
 A. Chassis Arrangement. t 
 
 1. What is the advantage of a three-point suspension for the 
 power plant instead of four points? 
 
 2. What is meant by the expression unit power plant? 
 
 3. Name three possible positions for the change gears. 
 
 4. What objection may be made to placing the change gears 
 on the rear axle? 
 
 B. Frames. 
 
 5. Of what kind of steel are frames made? 
 
 6. Why are frames usually riveted together? 
 
 7. What is the function of the reinforcing plates? 
 
 8. Why is the frame usually made deeper at the center than 
 at the ends? 
 
 9. Why is the frame made narrow at the front? 
 
 10. Describe the Ford frame. 
 
 11. Describe the power-plant suspension on the Ford. 
 
 12. Describe the power-plant suspension on one other make of 
 automobile. 
 
 13. What is a sub-frame? Name one make of car which uses 
 this construction. 
 
 C. Springs. 
 
 14. What is a laminated leaf spring? 
 
 15. State the function of the following parts: (a) the center 
 bolt, {b) the spring clip, (c) the eyes, {d) the spring blocks, (e) the 
 master leaf. 
 
CHASSIS ARRANGEMENT 
 
 , _ 5PRIN6 
 
 RrnnuN D Clip 
 
 ( 
 
 173 
 
 Fig. 83.— Laminated leaf spring. 
 
 Fig. 84.— Full elliptic spring. 
 
 Fig. 86.— Semi-elliptic spring. 
 
 pjg 8s.— Three-quarters elliptic spring. 
 
 Fig. 87.— Cantilever spring. 
 
 Fig. 88.— Platform Springs, 
 
174 AUTOMOBILE LABORATORY MANUAL 
 
 i6. Make a diagram of a laminated leaf spring and label the 
 parts named in question 15. 
 
 17. Explain or make diagrams showing how the following types 
 of springs are attached to the frame and to the axle: (a) semi- 
 eUiptical, (i) three-quarter eUiptical, (c) cantilever, {d) full 
 elliptical. 
 
 18. Describe the spring suspension of the Ford car. 
 
 19. Describe the spring suspension of one other make of auto- 
 mobile. 
 
 20. In the operation of a spring, where does friction occur? 
 
 21. What kind of lubricant should be used on springs and how 
 is it applied? 
 
REFERENCE BOOKS 
 
 A. Laboratory Reference Shelf^ — Required Books. 
 
 The Gasoline Automobile — Hobbs, Elliott, and Consoliver 3 copies 
 
 McGraw-Hill Book Co., Inc., N. Y. 
 Motor Vehicles and Their Engines — Frazer and Jones . 3 copies 
 
 D. Van Nostrand Co., N. Y. 
 Automobile and Gasoline Engine Encyclopedia — Dyke 3 copies 
 
 A. L. Dyke, St. Louis, Mo. 
 The Ford Manual . . 3 copies 
 
 The Ford Motor Co., Detroit, Mich. 
 The Model T Ford Car — Pagg . . 3 copies 
 
 Norman W. Henley Publishing Co., N. Y. 
 Practical Physics — Black and Davis 2 copies 
 
 The Macmillan Co., N. Y. 
 Practical Physics — Millikan, Gale, and Pyle 2 copies 
 
 Ginn & Co., N. Y. 
 Gasoline Automobiles — Moyer 2 copies 
 
 McGraw-Hill Book Co., Inc., N. Y. 
 
 B. Reference Books and Related Books. 
 
 Automobile Questions and Answers — Pag6. 
 
 Norman W. Henley Publishing Co., N. Y. 
 Automotive Repair — Wright 
 
 John Wiley & Sons, N. Y. 
 Modern Starting, Lighting and Ignition Systems — Pag6. 
 
 Norman W. Henley Publishing Co., N. Y. 
 Gas Engine Ignition — Norris, Winning and Weaver. 
 
 McGraw-Hill Book Co., Inc., N. Y. 
 Farm Motors — Potter. 
 
 McGraw-Hill Book Co., Inc., N. Y. 
 Gasoline and Kerosene Carburetors— P3.g6. 
 
 Norman W. Henley Publishing Co., N. Y. 
 
 175 
 
176 AUTOMOBILE LABORATORY MANUAL 
 
 The Modern Gasoline Automobile — Pag6. 
 
 Norman W. Henley Publishing Co., N. Y. 
 Storage Batteries Simplified — Pag6. 
 
 Norman W. Henley Publishing Co., N. Y. 
 Aviation Engines — Page. 
 
 Norman W. Henley Publishing Co., N. Y. 
 Motor-cycles Side Cars and Cycle Cars — Pag6. 
 
 Norman W. Henley Publishing Co., N. Y. 
 Automobile Charts — Pag6. 
 Location of Gasoline Engine Troubles. 
 Location of Carburetion Troubles. 
 Location of Ignition System Troubles. 
 Location of Cooling and Lubricating Troubles. 
 Location of Starting and Lighting System Faults. 
 Location of Ford Engine Troubles. 
 Location of Motor Cycle Troubles. 
 Lubrication of the Motor Car Chassis. 
 Norman W. Henley Publishing Co., N. Y. 
 
APPARATUS LIST 
 
 Note. The letters S. S. in this list refer to the Standard Scientific Co. 
 New York. 
 
 Experiments 
 
 I. Automobile Mechanisms — A. 
 
 i-a. One of the typical automobiles either new or used. Mount both 
 front and rear axles on a strong wooden stand so that wheels are 
 clear of the ground. 
 
 4. The Gasoline Engine — A. 
 
 4-a. Gasoline engine. Sears, Roebuck & Co., Chicago, 111. 
 
 4-6. Ignition-bottle. Heavy glass, narrow bottle, height 10 inches, 
 
 diameter I5 inches. S. S. Or use narrow olive bottle. 
 4-c. Rubber tube. S. S. 
 4-J. Dry cells. Any electrical supply house. 
 4-e. Telephone magneto with small lamp. S. S. 
 
 6. Carburetors — ^A. 
 
 6-a. Bunsen burner, Terrill's. S. S. 
 6-6. Ignition-bottle. Same as in 4-6. 
 6-c. Large glass jar or pail. 
 
 d-d. Sectional carburetor. Use Sectional Holley Model G, Holley 
 Bros. Co., Detroit, Mich., or other simple type of carburetor. 
 
 7. Carburetors — ^B. 
 
 7-a. Purchase simple carburetors from used-car dealers. Schebler 
 Model E and Kingston Model E. For addresses of manufac- 
 turers see Dyke. 
 
 177 
 
178 AUTOMOBILE LABORATORY MANUAL 
 
 8. AutomobUe Engine — ^A. 
 
 8-a. Ford chassis. New or used chassis. Remove the radiator, the 
 cylinder head, the dashboard, the transmission cover, the bottom 
 plate, and one piston with connecting rod. Mount both front 
 and rear axles on a wooden stand so that wheels are clear of the 
 ground. For electrical work mount the induction-coil box on the 
 frame at the left side of the engine. A separate wooden stand 
 should be provided for supporting the rear spring so that the rear 
 axle may be completely taken off. 
 
 13. Introductory Electrical Work — ^A. 
 
 13-a. Base block 5X5X2 inches. S. S. 
 
 13-6. Round battery jar 5J inches high by 2f inches diameter. S. S. 
 
 13-C. Ammonium chloride (sal ammoniac) technical. S. S. 
 
 13-d. Zinc battery rod. S. S. 
 
 13-C. Carbon rod from an old dry cell. 
 
 13-/. Bunsen burner, TerriU's. S. S. 
 
 13-g. Electric bell. Any electrical supply house, or S. S. 
 
 13-A. No. 24 insulated wire, double cotton. S. S. 
 
 13-t. Nitric acid. S. S. 
 
 14. Introductory Electrical Work — ^B. 
 
 14-a. Battery voltmeter, mounted. S. S. 
 
 14-6. 35-ampere battery ammeter, mounted. S. S. 
 
 14-C. Push-button. S. S. 
 
 15. Introductory Electrical Work — C. 
 
 15-0. Ring stand. S. S. 
 
 15-6. Ring-stand clamps. S. S. 
 
 15-C. 3-volt lamps. S. S. 
 
 1 5^. Small 3-volt motor. S. S. 
 
 15-e. Electric bell. S. S. 
 
 15-/. Battery voltmeter. S. S. 
 
 15-g. 3S-ampere battery ammeter, mounted. S. S. 
 
 iS-h. Push-button. S. S. 
 
 16. Introductory Electrical Work — D. 
 
 i6-a. Compass, pocket. S. S. 
 16-6. Push-button. S. S. 
 16-C. Electric bell. S. S. 
 
APPARATUS 179 
 
 17. The Electric Motor. 
 
 17-a. St. Louis motor. S. S. 
 
 ly-b. 3S-ampere battery ammeter, mounted. S, S.' 
 
 18. The Electric Generator. 
 
 18-0. Small hand-power generator. L. E. Knott Apparatus Co., 
 
 Boston, Mass. No. 97-148. 
 18-6. Small lamp. S. S. 
 18-C. 35-ampere battery ammeter. S. S. 
 i&-d. Battery voltmeter. S. S. 
 i8-e. Electric beU. S. S. 
 18-/. Small 3-volt motor. S. S. 
 18-g. Telephone magneto-generator. S. S. 
 
 19. Ignition Systems — ^A. 
 
 19-a. Vibrating induction coil.' Sears, Roebuck &< Co., Chicago. 
 
 No. 6A9234, or S. S. 
 19-J. Metal-ring stand. S. S. 
 I9-C. Automobile spark plug. Any automobMe-supply house;- 
 
 20. Ignition Systems — ^B. ■- 
 
 20-a. Use same coil listed in experiment 19. 
 
 20-6. Metal-ring stands. S. S. 
 
 20-c. Wooden block with four binding posts to represent a distributor. 
 
 S. S. 
 20-d. Non-vibrating induction coil (mafce-and-breafc ' spark coil). 
 
 Sears, Roebuck & Co., Chicago. 
 
 21. Storage Battery — A. 
 
 21-0. Simple demonstration battery with sheet lead plates. S. S. 
 
 21-6. Battery voltmeter, mounted. S. S. 
 
 21-C. Electric bell. Any electrical store or S. S. 
 
 2t-d. 2-voltlamp. S. S. 
 
 2i-e. Small 2-volt motor. S. S. 
 
 21-/. Lamp board and i-ampere lamp. S. S. 
 
 29. Valve Mechanisms — A. 
 
 29-0. Valve-spring compressor. Automobile supply house. 
 
i8o AUTOMOBILE LABORATORY MANUAL 
 
 30. Valve Mechanisms — B. 
 
 30-0. Valve push-rod with adjustment screw. Dealer in automobile 
 
 junk. 
 30-6. Valve grinding tools. Automobile supply house. 
 
 31. Ignition Induction Coils. 
 
 31-0. Vibrating induction coil. Sears, Roebuck & Co., Chicago 
 
 No. 6Ag234, or S. S. 
 31-6. Make-and-break coil. Sears, Roebuck & Co. 
 3J-C. Automobile induction coil. Dealer in used automobile supplies. 
 
 32. Ignition Systems — C. 
 
 32-a. Atwater-Kent ignition unit; type CC. Dealer in used ignition 
 
 systems or Atwater-Kent Co., Philadelphia, Pa. 
 32-6. Spark plugs. Any dealer. 
 32-c. Ring stands. S. S. 
 
 34. Ignition Systems— E. 
 
 Si-a. Remy Model RL ignition system. Dealer in used ignition parts 
 or Remy Electric Co., Anderson, Ind. 
 
 35. Ignition Systems — F. 
 
 35-0. Dealer in used parts or manufacturers, Bosch, type DV4 high- 
 tension magneto. Bosch Magneto Co., N. Y. Or Eisemann 
 type G4 high-tension magneto, Eisemann Magneto Co., N. Y. 
 Or Dixie magneto, Splitdorf Co., Newark, N. J. 
 
 36. Storage Battery— B. 
 
 36-0. Small lead storage battery in glass jar. Central Scientific Co., 
 Chicago. No. 1042 No. B. Write for catalogs to Electric 
 Storage Battery Co., Philadelphia, Pa., and WUlard Storage 
 Battery Co., Cleveland, O. 
 
 36-i. Battery hydrometer. Automobile supply dealer or Willard 
 Storage Battery Co., Cleveland, O. 
 
 36-c. Buy lamp sockets from any electrical dealer and make up a lamp 
 board resistance or buy a suitable rheostat; from S. S. 
 
APPARATUS i8i 
 
 47. Tires — ^A. 
 
 47-a. Tire levers. Automobile dealer. 
 47-i. Tire pump. Dealer. 
 
 48. Tires— B. 
 
 48-a. Tube bag. Dealer. 
 
 48-5. Cement and patches. Dealer. 
 
 48-c. Five-minute vulcanizer. Dealer. 
 
 50. Carburetors — C. 
 
 So-a. Carburetors. Dealer in used parts or an automobile junk dealer 
 or write to the manufacturers. For addresses see Dyke. 
 
 51. Carburetors — D. 
 
 51-a. Schebler Model E. Dealer in used parts or Wheeler & Schebler, 
 
 Indianapolis, Ind. 
 51-6. Kingston Model E. Dealer in used parts or Byrne, Kingston 
 
 & Co., Kokomo, Ind. 
 Si-c. Holley Model G. Dealer in used parts or from Holley Bros. 
 
 Co., Detroit, Mich. 
 
 54. Fuel Feed Systems. 
 
 S4-a. Stewart vacuum tank. Purchase a sectional tank from the 
 manufacturers, Stewart Warner Speedometer Corp., Chicago, 
 111., or buy a vacuum tank from a dealer in used parts. 
 
 57. Differential— A. 
 
 S 7~a. Small Meccano model of a differential. Meccano Co. , Inc., N. Y. 
 
 59. Alternating Currents. 
 
 SQ-o. Pocket compass. S. S. 
 
 Sg-b. Telephone magneto. S. S. 
 
 59-c. Battery voltmeter. S. S. 
 
 Sg-d. Electric bell. S. S. 
 
 SQ-e. Large coils of 1000 turns. S. S. 
 
i82 AUTOMOBILE LABORATORY MANUAL 
 
 6i. Automobile Electric Circuits — C. 
 
 6i-a. Electric generator (etc.). Use apparatus for experiment i8. 
 
 61-6. Telegraph sounder. S. S. 
 
 61-C. Automobile cut-out. Dealer in automobile ignition parts. 
 
 67. Pistons and Cyliders. 
 
 67-a. Use a Ford piston and the Ford engine cylinder. 
 
INDEX 
 
 Air cooling, 35. 
 
 Alignment of wheels, 65, 67. 
 
 Alternating currents, 144, 145, 146, 
 
 147. 
 Ammeter, 34, 35. 
 Ammeter, automobile, 57. 
 Amperes, 33, 34. 
 Anti-freezing mixtures, 61. 
 Armature, 45. 
 
 Atwater-Kent system, 77, 78, 79. 
 Automobile electric circuits, 151, 152- 
 Auxiliary air inlet, 14, 16. 
 Axle housing cap, 29. 
 Axle shaft, 29. 
 Axle shaft bearings, 69. 
 
 B 
 
 Bearings, 19, 171. 
 Bosch magneto, 88. 
 'Brakes, 2, 3, 7, 28, 29, 30, 108, 109, 
 
 no. 
 Brake bands, 108, 109. 
 Brake drum, 29. 
 Brake rods, 3, 108. 
 Brake shoe, 29. 
 Brushes, 45. 
 Bunsen burner, 13. 
 
 Cadillac carburetor, 131. 
 
 Camber, 68. 
 
 Cam, 20, 21. 
 
 Cam followers, 21. 
 
 Cam shaft, 18, 20, 21, 162. 
 
 Carburetion, 15. 
 
 Carburetors, 6, 11, 13, 14, 15, 16, 121 
 
 122, 124, 125, 126, 127, 128. 
 Carburetor adjustments, 17, 120. 
 Cells in parallel, 35. 
 Change-speed gears, 3, 95, 96, 97, 98, 
 
 99, 100, loi, 102, 103. 
 Charging circuit, SS. iSi- 
 Clutch, 2, 3, 6, 21, 64, 100, 103, I04; 
 
 los, 106, 107. 
 Commutator, 4^. 
 Compression, no, in, 112, 113. 
 Compression stroke, n. 
 Concentric float, 15. 
 Condenser, 73, 76. 
 Cone clutch, 106, 107. 
 Connecting rod, 8, 9, n, 162, 165. 
 CooUng systems, 4, 22, 25, 60. 
 Crankcase, 11, 18, 20. 
 Crankshaft, 18, 19, 20, 161, 162. 
 Cut-out, automatic, 57, 153, 155. 
 Cylinder, 9, 18, 21, 167. 
 Cylinder head, 21. 
 
 183 
 
i84 
 
 INDEX 
 
 Demountable rims, ii8, 119. 
 Differential, .i, 36, 64, 140, 141, 142, 
 
 143, 144- 
 Distributor, 49, 50, 86. 
 Dixie magneto, 88. 
 Drag link, 66. 
 Drive pinion, 69. 
 Dry cell, 30, 32. 
 
 Eccentric float, 15. 
 
 Electric bell, 3r, 40. 
 
 Electric circuits, 57. 
 
 Electric generator, 44, 56, 153, 154, 
 
 iSS- 
 Electric motor, 36, 41, 42, 43. 
 Electrolyte, 31. 
 Electromagnets, 38, 39, 43. 
 Engine, 2, 4, 18, 19, 20. 
 Engine adjustments, 93, 94. 
 Engine knocks, 162, 163, 164. 
 Engine mechanisms, 12. 
 Engine power, 167, 168, 169. 
 Engine troubles, 94, 95. 
 Exhaust valve, 9, 2r. 
 Explosion stroke, 11. 
 Explosive mixture, 7. 
 
 Field coil, 45. 
 Field poles, 45; 
 Float, 14, 16. 
 Float chamber, 14. 
 Float valve, 14, 16. 
 Flushing crankcase, 27. 
 Flywheel, 8, 21. 
 Force-feed system, 63. 
 Ford engine, 18, 19, 20. 
 Ford ignition,- 80, 81, 82, 83. 
 Ford magneto, 82, 149, 150. 
 
 Four-stroke engine, 11. 
 
 Frames, 172. 
 
 Franklin cooling system, 61. 
 
 Front axle, 65. 
 
 Fuel feed systems, 132, 133, 134, 135. 
 
 Full floating axle, 70. 
 
 Gas engine, 8, 9, 10, 11, 12. 
 Gasket, plug, 27. 
 Gasoline tank, 3. 
 Gather, 67. 
 Gears, 2, 3, 6, 64. 
 Gravity feed system, 132. 
 
 H 
 Head hghts, 57. 
 High-tension current, 48. 
 HoUey carburetor, 124. 
 Hub-brake cam, 29. 
 Hub key, 29. 
 
 I 
 Ignition, 8, 22, 46, 49, 50, 55, 77, 78, 
 
 79, 80, 81, 82, 83, 84, 8s, 86, 87, 
 
 88, 147, 148, 149, 150. 
 Ignition bottle, 7, 13. 
 Ignition circuit, 55, 152. 
 Ignition magnetos, 147. 
 Ignition, storage battery, 58, 151. 
 Ignition switch, 57. 
 Ignition timing, 138, 139. 
 Ignition troubles, 159, 160. 
 Illuminating gas mixture, 7. 
 Induction coil, 8, 46, 47, 48, 49, 50, 73. 
 Inlet valve, 9, 21. 
 Intake stroke, 11. 
 
 Jump spark, 10. 
 
 K 
 
 Kingston carburetor, 123, 124. 
 
INDEX 
 
 i8S 
 
 Lighting circuits, 58, 152. 
 Liquid cell, 30. 
 Live axle, 69. 
 Local action, 32. 
 Lock nut, 29. 
 Low-tension current, 48. 
 Low-tension magneto, 84. 
 Lubrication, 23, 26, 27, 28, 64. 
 
 M 
 Magneto, 8, 51, 82, 84, 85, 86, 87, 
 Main bearings, 21, 161. 
 Make and break coil, 9, 50, 75. 
 Manifolds, 25. 
 Marvel carburetor, 130. 
 Measurements, electrical, 33, 34. 
 Miniature wiring system, 36. 
 Mixing chamber, 14, 16. 
 Mixing valve, 8, 9. 
 Mixture, combustible, 13. 
 Muffler, 3, 171. 
 Multiple disc clutch, 104, 105. 
 
 N 
 Negative terminal, 52, 53. 
 
 O 
 
 Oil cocks, Ford, 24. 
 
 Oil cup, 8. 
 
 Oil tube. Ford, 24. 
 
 Oil pump, 62. 
 
 Oiling systems, 26, 62, 63. 
 
 Packard carburetor, 130. 
 Permanent magnets, 38, 39, 41, 42. 
 Pierce- Arrow carburetor, 131. 
 Piston, 9, 20, 21, 16s, 166, 167- 
 Planetary gears, 99, 100, loi, 102, 103. 
 Polarization, 31. 
 
 Positive terminal, dry cell, a. 
 
 Power plant, 3. 
 
 Pressure feed system, 132. 
 
 Primary circuit, 47, 73. 
 
 Propeller shaft, 2, 3. 
 
 Pump cooling system, 60, 61. 
 
 R 
 
 Radiator, 3. 
 
 Rayfield carburetor, 129. 
 Rear axle, 64, 68. 
 Regulation, current, 155, 156. 
 Remy, low-tension, 84, 148. 
 Resistance lamp, 52. 
 Rich mixture, 13. 
 Rim, split, 118. 
 
 S 
 Schebler carburetor, 122. 
 Secondary circuit, 47, 48, 49, 50, 73. 
 Semi-floating axle, 70. 
 Sequence of firing, 22. 
 Sneeze back, 13. 
 Spark coil, 9. 
 Spark plug, 47, 48. 
 Splash oiling system, 62. 
 Spray nozzle, 14. 
 Springs, 172, 173, 174. 
 Starting circuit, 59, 151. 
 Steering knuckle, 66. 
 Steering mechanism, 65, 66, i6g, 170. 
 Stewart carburetor, 131. 
 Storage battery, 3, 51, 52, 53, 54, 57. 
 
 89, 90, 91, 92. 
 Stromberg carburetor, 125, 126. 
 
 Telephone magneto, 46, 146. 
 Thermo-siphon, 22, 25.- 
 Thermostatic valve, 60, 61. 
 Three-quarter-floating axle, 70. 
 Tie rod, 66. 
 
i86 
 
 INDEX y 
 
 Tillotson carburetor, 130. 
 
 Timer, 49, 50, 76, 86. 
 
 Timing gears, 20, 58. 
 
 Tires, 114, 115, 116, 117, 118, 119- 
 
 Tire, patching, 116. 
 
 Tire testing, 116. 
 
 Transmission, 64. 
 
 U 
 Universal joint, 2, 3, 64. 
 
 Vacumn feed, 134, 13s, 136. 
 Valves, 19, 20, 21, ^a, 72. 
 Valve adjustments, 72.- 
 
 Valve grinding, 72. 
 Valve-stem guides, 71. 
 Valve timing, 136, 137, 138- 
 Venturi tube, 15. 
 Vibrator, 73. 
 Volts, 33. 
 Voltmeter, 34, 35. 
 Vulcanizing, 117. 
 
 W 
 
 Water jacket, ig. 
 Wheels, 171. 
 Wrist pin, 21. 
 
 Z 
 Zenith carburetor, 127, 128.