Transcriber’s Notes:—
Italic text is clothed with _underscores_.
Bold text is clothed with =equal signs=.
The spelling, hyphenation, punctuation and accentuation are as the
original, except for apparent typographical errors which have been
corrected.
[Illustration:
Courtesy of Allen Motor Co.
SECTIONAL VIEW OF A MODERN AUTOMOBILE WITH FOUR-CYLINDER ENGINE]
Putnam’s
Automobile Handbook
The Care and Management of the
Modern Motor-Car
By
H. Clifford Brokaw
Principal
And
Charles A. Starr
Of the Staff
of the Automobile School of the West Side Young Men’s
Christian Association of New York City
_Illustrated_
G. P. Putnam’s Sons
New York and London
The Knickerbocker Press
1918
COPYRIGHT, 1918
BY
G. P. PUTNAM’S SONS
The Knickerbocker Press, New York
FOREWORD
Much of the material, here assembled for the first time, has been
printed in the automobile section of New York City newspapers. It
has stood the scrutiny of the wisest men in the automobile trade and
has been read eagerly by owners within the sphere of the newspapers’
limited circulation; some of it has been reprinted in papers all over
the country, which is evidence enough of its practical value.
The publication, however, has been without sequence and all of it
has not appeared in any one paper. Moreover it has been reassembled
and rewritten and much has been added to round out the story of the
automobile and to adapt the material to the use of everyday men who do
not understand or care for the more technical works.
It should not be taken as the last word concerning the auto. That
will not be written until after the automobile has been driven out of
business by the airplane or something else and is as obsolete as the
oxcart of a century or two ago. There is nothing new in the principle
of the gas engine, but new appliances and new methods are constantly
being invented and discovered.
All that is herein contained is the result of years of experience
at the Automobile School of the West Side Young Men’s Christian
Association, New York City. This was one of the pioneer schools and
for fourteen years has turned out more than 1000 trained drivers each
year who know their engine and working parts thoroughly. Last year the
number was nearly 2500. Naturally in handling these thousands of bright
men the instructors were stimulated and themselves learned as they
taught. The consensus of this ripe experience is given here.
Lest there be misunderstanding, it were better said at once that if the
reader has come to this book to learn how to be a garage mechanic, how
to qualify as an expert in automotive technique, or how to learn common
sense, he should at once seek another source of information. This book
makes no pretensions of teaching the last word in automobile repair.
But if the automobile owner desires to have a working knowledge of his
car, to know how to find and overcome the ordinary ills and troubles to
which it is subject, and how to diagnose and prescribe for it when it
begins to wheeze or squeak or groan or knock, let him read on. The book
is for him.
In other words this is not a _sine qua non_, but a friend in need; it
is not a know-it-all, but a first-aid treatise. It is a leaf—several
in fact—from the book of experience, relating not to the engineering
problems of the automobile, but to the things which the engineer
overlooked or could not solve, and which the ingenuity of men who lay
no claim to the title of engineer, has enabled them to learn so that
they may take a bucking auto and make it feed out of their hands and
stand without hitching.
One of the first essentials of an automobile is that it shall go, and
that no amount of perversity shall prevent the owner from “driving it
back home under its own power.” Anyone may be towed in, if there is a
horse or another automobile handy; the wise owner will prepare himself
to avoid this. Except for serious breaks of parts, or forgetfulness
which permits oil or gas supply to run out, there is seldom reason why
the average owner should not “get out and get under” to find out what
the trouble is and, having found it, to remove the cause and start the
engine. It usually should take only a few minutes. System in locating
trouble and knowledge of what to do to remove the trouble are within
the compass of all; if there also reside within the individual a few
grains of common sense, his problem is simplified, his troubles are
lightened.
Let it be said also that this book does not in any way pretend to
supersede an automobile school for the owner who desires to make all
his ordinary repairs, and do more puttering about the car than the
average owner cares for. All owners would save the cost of instruction
many times over and repay the lost time by taking a course of
instruction in a reputable school. Many Y. M. C. A. branches all over
the land have well equipped schools, and there are many others in the
cities; there are also many where time spent would be wasted. There are
several in one of our large cities where the expense is very small, but
it is dear at any price. The “course” consists largely in putting the
student to work in a garage as an apprentice, where his instruction
is confined to verbal orders of how to repair a car which comes in.
In time, of course, the student comes across a large variety of
troubles, depending upon the character of the garage trade. Meanwhile
the garage-auto-school proprietor permits the student to pay for the
privilege of doing the repair work at the institution. No wonder the
course is advertised as unlimited!
It should be understood that this book does not pretend to tell all the
troubles attaching to automobiles and how to end them; but it covers
the general run of difficulties experienced on the road and a close
study of its pages and an application of its advice will make an owner
who has the least mechanical genius independent of the garage man, with
his delay and extravagant charges; at least it will enable him to get
to the home garage in most cases, where repairs may be effected with a
minimum of expense and annoyance.
Upon this basis and with this understanding, the automobile owner may
safely pin his faith to what follows and plunge at once into its depths
without fear.
H. C. B.
C. A. S.
CONTENTS
CHAPTER PAGE
I.—WHAT TO DO ON PURCHASING A CAR 1
II.—SOME THINGS TO AVOID 7
III.—WHAT AN AUTOMOBILE IS 12
IV.—WHAT MAKES THE ENGINE GO 21
V.—EQUIPMENT AND ACCESSORIES 26
VI.—IF WELL “SLICKED” THE ENGINE RUNS 33
VII.—WHERE LUBRICATION IS NEGLECTED 39
VIII.—SOMETIMES THE CAR SMOKES 46
IX.—THE CARBURETOR AND ITS FAILINGS 51
X.—GETTING THE MOST OUT OF A GALLON OF GAS 58
XI.—THINGS WHICH MAKE GAS BILLS HIGH 63
XII.—CARE OF THE TIRES 69
XIII.—SKIDDING MAY BE MINIMIZED 76
XIV.—“CAN’T-SLIP HEELS” LESSEN SKIDDING 84
XV.—AVOID NEWLY OILED ROADS 90
XVI.—WATCH YOUR BRAKES 93
XVII.—WHY THE AUTO STEERS EASILY 101
XVIII.—THE ELUSIVE “JUICE” 108
XIX.—PUTTING THE KICK IN THE SPARK 116
XX.—WHAT’S THE TROUBLE WITH MY BATTERY? 123
XXI.—WHY GEARS STRIP 130
XXII.—THE GEAR-SHIFTING BUGABOO 137
XXIII.—THE MUFFLER 143
XXIV.—YOUR BEARINGS 149
XXV.—DRIVING THE CAR 156
XXVI.—WHERE EXTRA CAUTION IS NECESSARY 178
XXVII.—AN AUTO FURNACE FOR WINTER 184
XXVIII.—THE COOLING SYSTEM IN WINTER 191
XXIX.—OVERHEATING THE ENGINE IN SUMMER 197
XXX.—SOME OTHER HOT-WEATHER TIPS 203
XXXI.—HOT-WEATHER TIRE EXPANSION 209
XXXII.—GUARDING AGAINST FIRE 214
XXXIII.—DON’T RUN AWAY FROM A FIRE 220
XXXIV.—DEATH IN THE GASOLINE 224
XXXV.—SHIFTING GEARS ON HILLS 229
XXXVI.—KEEPING THE CAR SLEEK 236
XXXVII.—SOME THINGS A TOURIST SHOULD KNOW 244
XXXVIII.—LITTLE KNOCKS ARE HARDLY BOOSTS 251
XXXIX.—SOME OTHER CAUSES OF KNOCKING 255
XL.—CHASSIS KNOCKS 262
XLI.—KEEPING DOWN THE AUTO UPKEEP 267
XLII.—HUNTING TROUBLE 272
XLIII.—MORE TROUBLE 280
XLIV.—DON’T TAKE THINGS FOR GRANTED 285
XLV.—BLOWING YOUR OWN HORN 294
XLVI.—WOMEN AS DRIVERS 300
XLVII.—MISCELLANEOUS RULES 308
XLVIII.—THE GOLDEN RULE OF MOTORING 317
INDEX 331
ILLUSTRATIONS
PAGE
SECTIONAL VIEW OF A MODERN AUTOMOBILE
WITH FOUR-CYLINDER ENGINE _Frontispiece_
CHASSIS PLAN OF THE SAME AUTOMOBILE 14
SECTIONAL VIEW OF A FOUR-CYLINDER ENGINE
WITH SPECIAL REFERENCE TO PARTS CONNECTED
WITH LUBRICATION 34
REAR WHEEL AND BRAKE DRUM REMOVED,
SHOWING EXTERNAL AND INTERNAL BRAKE
BANDS AND MECHANISM 98
THEN HE WENT TO SCHOOL TO LEARN SOME
MORE ABOUT HIS CAR 125
DIAGRAM OF THREE SPEED AND REVERSE GEAR 132
BLOCK OF STEEL, AND THE GEAR WHEEL WHICH
WAS HAMMERED FROM IT 138
BRAKE LEVERS AND LINKAGE, SHOWING EQUALIZING
ROD AND SPRINGS 246
SHE IS ACCUMULATING KNOWLEDGE OF AN
INTRICATE MACHINE—AND SHE IS FASCINATED 305
Putnam’s Automobile Handbook
CHAPTER I
WHAT TO DO UPON PURCHASING A CAR
The man who buys a car will receive from the salesman a certain amount
of instruction as to running it. He will be taught how to manipulate
the pedals and levers, switches and other devices of the equipment and,
if necessary, how to run the car. He will be given, also, certain books
of instructions.
It is presumable that almost any man will remember enough of the
salesman’s patter to enable him to get home with the car, and that some
bits of memory as to the instruction books will remain. But will the
owner get out those books and go to school awhile with them? Not if he
is the average owner. Probably he looks upon them as mere catalogues
for ordering repair parts—well enough when needed. Do not make that
mistake. There is no other book printed, no matter how complete, which
supersedes or which can be substituted for the manufacturer’s book
concerning his own car. It was not printed just to consume paper and
ink; the manufacturer had no idea you would cut out the pictures and
paste them about the garage. He and his assistants spent a large amount
of time and a larger amount of gray matter in preparing those books so
that you, Mr. Owner, would know how your car is built, what it ought to
do, and why it won’t unless you do certain things. The books contain
in a small compass practically everything about your particular car.
The owner should master the contents first of all. Nothing can take its
place.
If the owner has not read the instructions, lay down this volume right
now, go to the garage, and get the books and read them over. If you
haven’t read them they are still in the car. The manufacturer made
certain that the owner could not claim the books were not received,
by tacking them fast under the seat or elsewhere so that they could
not get away and so that a forgetful salesman would not overlook this
important matter. Get them out and lay the basis of what is to follow.
Doubtless the owner will find that the manufacturer has, for instance,
given certain instructions concerning lubrication, perhaps has
specified certain kinds of lubricants. Now, no matter how much you
may know about the subject of lubrication, rest assured that the
manufacturer has had an engineer study out the lubrication of his car
and what he writes concerning it is the last word and it should be
followed implicitly. All that is contained in these pages upon the
subject of lubrication is explanatory and corrective and in no way can
take the place of the manufacturer’s advice for the particular car.
The same thing is true as to tires, or brakes, or steering gear, or
any other part of the mechanism. Read his book first and then turn to
the appropriate chapter here and you will find no divergence, only
interpretation, clarification, supplementary advice.
Probably it would be well to remind the owner that nine-tenths of the
complaints which reach the manufacturer or his service stations, show
that the owners making the “holler” confess that they had not read the
books given them with the car. It has become such a serious thing that
at least one manufacturer has started schools for purchasers of the
make, where, at a nominal compensation, they may be made to read the
instructions and be given a visualization of what they mean. All owners
cannot visit the centers where such schools are maintained, and all
manufacturers do not maintain them now, though it may be necessary in
the near future. The fact that it is necessary, however, should leave
the impress upon the reader’s mind of the importance of the subject.
The owner, whether he possess a “flivver,” or an edition _de luxe_,
has about as much money tied up in his car as he feels he can devote
to that form of pleasure or to business. It is an investment which
will, or will not, bring commensurate returns in money, or moments,
well spent; it can be made an indispensable aid to both business and
pleasure, or it may become an unsufferable nuisance in either. The
value of a car depends not upon the amount of the purchase price, but
upon what can be gotten out of it: its service, its dependability and
general reliability; that and the low cost of upkeep and operation.
Would it not seem reasonable, therefore, for the owner to give as much
thought and study to the machine which propels him and his merchandise
as to the machine in the factory which produces the merchandise; ought
he not to understand how and why and wherefore it propels him—or why
not?
Few men there be who would consign their bodies to the mercy of wind
and waves if they did not believe that a competent captain and engineer
were aboard the craft, or to a railway train were there not an engineer
and conductor at hand to look to his safety. Why should he place
himself and loved ones in a motor car and start off on a trip with an
uncertain hand at the steering wheel, with no one aboard competent to
rule the engine, or to know if all other parts of the mechanism are
properly adjusted, when a maladjustment may mean danger and even death?
One would not waste sympathy upon the owner himself in case of an
accident through ignorance, but the fate of others in his keeping
prompts the sounding of a warning.
Years ago traveling sign painters decorated trees and rail fences and
barns along the railways with injunctions of a religious nature, such
as “Prepare to Meet Thy God.” The last time the writer was back “at the
farm” this identical message confronted him from a big rock alongside
the railway crossing, as it did thirty or more years ago. Only this
time it seemed appropriate, for there was more recklessness shown than
one cares to witness regularly—it is too nerve-racking.
When one considers that a defective brake, a worn-through steering
knuckle, or any one of a number of broken parts—broken because
neglected—may be the particular weapon selected by the fool-killer,
the owner who cares for his bones, or for the lives of his passengers,
would better spend a few hours occasionally in looking after his car
and in finding out all that is possible about it.
Even though the owner can afford a chauffeur who “knows all about an
auto,” it is noticeable that chauffeurs have a way of forgetting, that
they loaf on the job shamefully, that they conspire with the supply
dealer to run the cost of upkeep to skyline altitudes, and are little
more immune from road troubles than the common or garden variety of
owner. The owner who knows can detect all these lapses from strict
rectitude, to the comfort of his person and the safety of his bank
balance.
So, now, having turned to the manufacturer’s books of instructions and
pondered over the warnings here given, the reader may safely pass on to
the chapters dealing with the beast he is called upon to tame.
CHAPTER II
SOME THINGS TO AVOID
When a certain character of history, long touted as “the wisest guy
ever,” uttered his famous “Wisdom crieth aloud in the street,” and
along with it, “Fools hate knowledge,” he must have had a vision of the
present day, when there is so much and so little known about the chief
mode of transportation, the automobile; so much by those who really
have studied its mechanical principles, and so little by those who are
running them about the highways. Yet in this day of automobile schools
and service stations there is no need of a single individual being
ignorant, nor of his coming under the condemnation of the same wise
one: “The careless ease of fools shall destroy them.”
Give me an individual of average intelligence in overalls and jumper
and a mind devoid of the “I know it” error and 99.99 per cent. of such
can be taught to “make the auto auto as it really ought to auto.” The
chief obstacle is the half knowledge—half error—which some possess.
Josh Billings once said: “I’d rather not know so much than know a lot
that is not so.” The reader will get the idea.
One of the hardest things for the average man to learn is not to do
useless things. Over and over folks will do things contrary to all
rules and instructions and make extra work for themselves. In a school
it is a good thing, perhaps, for it enables the instructor to point
out the futility of going at the thing wrong end first. There was one
class at the West Side Y. M. C. A. school particularly stupid in this
respect. They were set to locating engine troubles, forgot all about
the rules and took turns cranking the engine, expecting in that way to
find out why the engine would not run. The instructor, looking into
the classroom, found how things were going. All but one student were
intent upon turning over the engine; that one man stood in one corner
grinning, apparently having a good time with himself. The instructor in
feigned amazement called out to him:
“Here, why are you not cranking the engine, too?”
With a grin perfectly idiotic the fellow drawled out:
“What’s the use of cranking if she ain’t goin’ to run?”
The reader can figure out for himself the relative degrees of idiocy
or stupidity in that class. The instructor quickly set them to work by
rule and they all knew in a few minutes that troubles are not located
by cranking alone. The reader who will give careful attention to the
instructions herein contained, and who will follow closely the rules,
will not be cranking the engine when he should be cleaning a spark
plug, or adjusting the carburetor, or mending a broken wire. He will
learn that there is a sequence in every little job about the auto which
tends to lessen the labor and to produce the best result, just as there
is in keeping a set of books, or in running a farm.
The carpenter who does his work without plans usually is dubbed a
“wood butcher.” The inference is that the man who would care for his
automobile should learn to do it in a systematic way, according to
rule, doing everything always the same way and in the same order.
Thus the labor becomes a habit and is performed quickly and easily.
At the same time habit must not be allowed to become a rut; the owner
must preserve originality and initiative, and native ingenuity is
invaluable.
Particularly it is wise to avoid the idea that at the first sign of
something wrong one knows just what the trouble is. Probably no one
thing has caused more unnecessary work and unnecessary expletive than
jumping at a conclusion. Have a rule and go by it. Under the chapter
relating to troubles there will be found a rule for locating them. It
does not matter so much where one starts if it is followed through when
started. Experience will lead one in time to select the starting point,
either under the heading ignition, or gasoline, or other heading,
the symptoms indicating generally to the experienced ear what is the
matter; but there is so much chance of error in this guess that the
rule must be remembered and closely followed.
It takes three things to start a gas engine running: gasoline in the
proper mixture, compression, and ignition. To keep it running we must
add a lubricating and a cooling system. There must also be free exhaust
for burned gases. While there are many phases of each, it is necessary
for the owner to get these things fixed in his, mind first. Everything
else is extraneous.
There is something else to avoid. Avoid giving offense to the policeman
on the street, and avoid running away if you have had an accident or
are hailed by the traffic man. It does not pay, and will make added
trouble, unless you are as fortunate in explanations as was a fellow
who was caught by the officer in front of the Automobile School. He
had hit someone and instead of stopping as the law provided, he gave a
hasty look, saw no policeman, and shot ahead, turning the next corner.
He dodged in and out of several streets, not seeing the motorcycle
policeman chasing him. When caught and stopped he was asked why he was
running away.
“Me running away?” he asked. “I was not running away, I was just trying
to find a cop to report the accident.”
It worked that time, but it is not safe to trust the expedient under
other circumstances.
CHAPTER III
WHAT AN AUTOMOBILE IS
It matters not whether one call it an automobile, a tin lizzie, a gas
wagon, or what not, it consists of a steel frame upon which are mounted
wheels, an engine, appliances for connecting the engine to the driving
wheels, a fuel supply tank, a system for producing ignition at the
right moment, and appliances for regulating the speed of the engine and
the direction of the car. A seat for the driver and sundry pedals and
levers are needed to accomplish speed and steering control, and sundry
other parts have their place, but the above covers in a general way the
necessities of an automobile.
An automobile, as the name suggests, is a car which contains its own
propelling force and to which it is not necessary to hitch a horse, or
steam engine, or something else to make it go. This in spite of the
fact that occasionally it _is_ necessary to hitch something else to an
auto to make it go.
The assembly, generally speaking, consists of the chassis,
corresponding to the running gear of a wagon; the engine, mounted on
the chassis; and the body.
The chassis usually is made of angle iron riveted together in form
convenient for supporting the other parts. This rests upon the springs
which take up the road shocks in part, and the springs rest upon the
axles.
The rear axles—there is a separate axle for each rear wheel—are fixed,
that is, they keep the wheels from oscillating, and they are joined
in the center by the differential, a device driving the axle shafts
by which one wheel is permitted to revolve at a differing speed as
compared with the other, in turning a corner. Since, in turning, the
outer wheel must travel a much longer distance than the inside wheel,
if no device were installed to take up this difference, the outer wheel
would scrape over the ground on every curve, or the inner wheel would
spin without forward motion. In either event it would be disastrous to
tires.
To keep the differential housing from twisting, a torque rod or tube
connects it to the frame; to keep the rear axles at right angles to
the frame and to transmit the driving thrust to the load, radius rods
connect the axles to the frame forward.
The forward axle, unlike in an ordinary wagon, is fastened to the
chassis frame, through springs, and does not turn. On either end is a
yoke from which is suspended a steering knuckle, the wheel turning on a
tapered spindle forged with the knuckle. The two knuckles are fastened
together by a tie rod, which has some form of a turn buckle by which
the wheels may be made to run parallel, or practically so. As a matter
of fact the wheels are not parallel. They foregather slightly, so that
the lines, projected forward far enough, would meet and make a pointed
effect, like the bow of a boat. Its effect is to bring a slight but
constant pressure upon both wheels and makes them less likely to swerve
through contact with road unevenness. Also the wheels undergather, so
that the load is brought over the center of knuckle support, minimizing
the strain.
This deviation of the wheels from true produces a very slight wear on
the tires, but it is more than compensated for by the other advantages
noted. The deviation is worked out scientifically and the owner need
not trouble himself about it. His only concern is that the tie rod
be not bent so that the foregather is increased, when there would be
excess wear of tires.
[Illustration:
Courtesy of Allen Motor Co.
CHASSIS OF A MODERN AUTOMOBILE WITH FOUR-CYLINDER ENGINE]
The brake drums are attached to the rear wheels and have inside and
outside bands with mechanism to tighten them against the drum providing
the necessary friction. The levers which connect the bands to the brake
pedal or emergency lever are termed the brake linkage.
The motor, or engine, rests upon the chassis frame forward, being
fastened thereto by bolts. Forward of it is a radiator, if it is a
water-cooled motor, to which it is connected by pipes; the cooling
system may be either pump or thermo-syphon type. Some few motors are
air-cooled. The principle of cooling is that the motor should be kept
just cool enough to prevent the lubricating oil from burning off the
cylinder walls.
Attached to the motor are the carburetor, in which air and gasoline
are mixed properly for rapid combustion, wires to supply ignition to
the mixture at the proper time, a device for giving lubrication, and
exhaust pipes leading to the muffler, the latter designed to stifle the
noise of rapid explosions, which otherwise would be deafening.
The ignition system may be either battery and coil, or high-tension
magneto which has its own coil and distributor, or a combination of
both these systems. Where there is a self-starter there is a storage
battery, which supplies current to the starting motor, and from which
the ignition current is drawn, and a generator to keep the battery
charged, and the generator may be provided with a circuit breaker and
distributor, or a separate magneto or coil may be used.
The lubricating device may either be a gravity or force-feed oiler
system with pipes leading to the various bearings, or the chief
lubrication may be by the splash system, where a reservoir of oil is
kept under the crank case from which it is pumped to oil pans under the
cranks, being splashed by projections which dip into the oil and throw
it all over the inside mechanism.
Also attached to the carburetor is the pipe from the fuel supply tank.
This supply may come by gravity or under pressure, and a late device
which is furnished with many cars is a vacuum gravity system, the
gasoline being drawn from the main tank, by a vacuum created in the
intake manifold, into a small container attached under the hood, whence
it flows by gravity to the carburetor, maintaining a uniform supply.
The motor consists of one or more cylinders, inside of each being a
piston which fits tight, the escape of gas being further prevented by
piston rings which seal the cylinder with the aid of the lubricating
oil. The pistons are attached to a connecting rod by a wrist pin,
the connecting rod being attached at the other end to the crank which
rests in bearings. The action of the engine is that by drawing down the
piston a vacuum is created in the upper part of the cylinder called the
combustion chamber. At the right moment an inlet valve is opened and a
charge of gas and air, called mixture, is sucked in. The valve closes
and the piston rising compresses the charge. When the piston reaches
its highest point a spark is introduced through spark plug or igniter.
This fires the mixture, bringing a rapid expansion, and this drives the
piston downward, producing force. This revolves the crank shaft, which
turns the force into rotary motion. This operation repeated rapidly
furnishes the motion which drives the car. The fly wheel carries the
crank over the strokes which do not produce power.
There are four strokes to each motor cycle. The first, which takes in
the mixture, is called the suction stroke; the next is the compression
stroke, the third is the power stroke, and the last is the exhaust
stroke when the burned gases are expelled from the combustion chamber.
These four strokes take two complete revolutions of the crank shaft, so
that the four _cycle_ is really two _circles_.
Power having been created and turned into motion, the next step is to
connect it to the propelling or drive wheels. The first device for
controlling the power is the clutch, which provides means of applying
or cutting off the power or motion quickly without stopping the engine.
This is done by friction in some form. The most common are the cone
clutch, where male and female cones are engaged by pressure, the
friction transmitting the power to the driving shaft; and the multiple
disc clutch, where numerous thin discs of metal or metal and textile
material are compressed together by a lever and transmit the power.
To provide for varying speeds and for reversing, also extra power
to the rear wheels for hill climbing, sandy roads, etc., gears are
necessary. In a general way this is a set of cog wheels of varying
sizes, so arranged on parallel shafts that by engaging different size
gears on the shafts a certain speed will be transmitted, other gear
sets producing another speed or a reverse motion. The diagram in
Chapter XXI. shows the usual form of construction. Three speeds and
reverse usually are provided, though some cars have four speeds. These
gear sets are engaged successively until the desired speed is reached.
From the gear case the power is transmitted by the drive shaft, which
has one or two universal joints to take up any misalignment and to
enable installing the engine level and yet transmit the power to the
driving axles, through the differential, at another level or angle, or
at varying angles due to spring action.
Upon each of the wheels is a tire consisting of a rubber and fabric
casing, enclosing a soft rubber tube with a valve by which it may be
inflated. The purpose of the tires is to absorb road shocks and make
riding easy, as well as to keep the car from jolting to pieces. The
tires are of varying composition and form and are attached to the rims
in differing ways. Many auto trucks use solid rubber tires.
Without going into detail, the foregoing gives the makeup of the car
and the simple principles of its operation. To control the car requires
various other parts. The first is the steering wheel and its mechanism.
The wheel is mounted on a shaft running within a tube, and to the lower
end of this shaft is a worm controlling a gear, and by levers and ball
joints operating the steering knuckle on one of the front wheels, the
other being operated simultaneously by the tie rod connection. On the
steering wheel or steering column are mounted the spark-timing lever
and the throttle lever. The spark lever regulates the time of the
spark within the combustion chamber and the throttle the amount of
mixture admitted to the combustion chamber.
At the feet of the driver are the pedal for engaging the clutch, that
for applying the brake, and the accelerator pedal, which operates the
throttle as well as the lever before mentioned. The throttle lever on
the steering column is for the regular running adjustment, while the
accelerator pedal is for temporary increase of the mixture in starting
or in speeding up. There may also be a pedal for the self-starter,
though the switch often is upon the dash. On the Ford and some other
cars the gear shift is controlled by pedals, but usually the shift is
made by a lever placed convenient to the right hand of the driver.
With it is installed also the emergency brake lever, which is used for
locking the car when standing and for alternating with the foot brake
on long hills.
On the dashboard may be mounted the ignition and lighting switch, the
speedometer, sight oil feed, and sundry other dials and switches,
depending upon the fastidiousness of the owner. Where there is a
self-starter there is a charge and discharge dial, the ammeter, which
tells whether the generator is working, and how.
CHAPTER IV
WHAT MAKES THE ENGINE GO
As has been stated on a previous page, it takes three things to start
an engine and three more to keep it going. The first three essentials
are a proper mixture of gasoline and air, ignition at the right moment,
and compression.
Gasoline will continue to burn after ignition, but, contrary to the
common idea, it will not explode unless confined, and not even then
unless it has vaporized and the vapor is mixed with air. It takes
about two hundred cubic feet of air to a pint of gasoline vaporized
to produce good combustion, though the air supply is usually much
more than this to insure carrying off the unburned nitrogen from the
air. For starting and speeding up, more gasoline is admitted to the
vaporizing chamber as the rich mixture ignites more quickly, but for
running, a leaner mixture produces better results.
But whatever the mixture which is burned, there would be little or no
power produced if the mixture were not confined under pressure. It is,
of course, a fact that a tank filled with gasoline vapor and air will
explode with great force if ignited, though there be only the ordinary
atmospheric pressure upon the tank. But it must be remembered that
if the pressure were sixty or seventy pounds to the square inch the
explosion would destroy everything in the vicinity. Taking advantage of
this fact the designers of the gasoline engine provided for compressing
the gas before ignition, to produce the greatest amount of power for
driving the car. Valves are provided which admit the charge of mixture
to the combustion chamber, closing tight after the charge is received.
Then the piston rises, compressing the contents of the combustion
chamber until a pressure of between forty and seventy-five pounds per
square inch is reached. It is upon the principle of the muzzle-loading
rifle or shotgun, or in blasting, where the charge is tamped down, or
confined by wads, and the exploding powder is held until the pressure
sends the bullet on its errand, or rends the rock.
Just as the piston reaches the highest point, and the compression is at
the maximum, a spark is introduced into the combustion chamber. Under
the pressure the gases burn much more rapidly and the explosive force
is greater. The gas does not burn instantaneously, however. It takes
a distinct interval of time for all the gas mixture to ignite; for
this reason, when the engine is running under its own power, the spark
comes just before the time of greatest pressure, and before the piston
reaches top center, so that by the time the piston starts the downward
stroke the highest efficiency of power will have been reached. For this
reason the spark-timing control lever is advanced after the engine is
started to give the best results. But the engine is always cranked with
the spark fully retarded.
The carburetor, meanwhile, has been called upon to send into the
combustion chamber through the intake manifold and intake valves a
charge of gas mixture; the quantity is regulated by the throttle. For
starting, a lever is manipulated which depresses the float in the fuel
chamber of the carburetor, permitting an extra supply to be drawn into
the mixing chamber, thus making the mixture richer and more readily
fired. When the engine has started running, the throttle is closed to
a point where the motor does not race. The correct running position is
given by the manufacturer and experience will soon determine where the
best results are obtained.
The ignition system must deliver to the combustion chamber at the right
instant a spark of sufficient intensity to fire the charge. Whether the
electric current is obtained from battery or magneto, it must be hot
enough to do its work and there must be a timing device which will send
the spark into each cylinder when it is needed. These come in several
forms and are described in detail in the manufacturer’s instruction
books, in connection with the ignition and wiring diagrams.
The compression is maintained when the piston rings and grooves are
free from gummed oil or carbon and move freely; when the cylinder walls
are not worn oval by a slapping piston, or creased by carbon, and when
a film of lubricating oil is constant on the side walls and when valves
are properly seated. Loss of compression means loss of power and the
cylinders should be tested every little while to make sure that no
cylinder is failing to do its duty. More will be said concerning this
later, as well as of minor things which may affect the compression.
As has been mentioned, to keep the engine running for any length of
time there must be a cooling system, a system of lubrication, and a
free exhaust. Once the owner comprehends the simplicity of gas-engine
operation, he can begin to trace each part of the operation, learning
all there is to know concerning the several steps in his own motor, and
absorbing the specific knowledge which will enable him to care for his
car efficiently and economically.