Every boy and almost every man has longed to ride on a locomotive, and
has dreamed of holding the throttle-lever and of feeling the great
machine move under him in answer to his will. Many of us have protested
vigorously that we wanted to become grimy, hard-working firemen for the
sake of having to do with the "iron horse."
It is this joy of control that comes to the driver of an automobile
which is one of the motor-car's chief attractions: it is the longing of
the boy to run a locomotive reproduced in the grown-up.
The ponderous, snorting, thundering locomotive, towering high above its
steel road, seems far removed from the swift, crouching, almost
noiseless motor-car, and yet the relationship is very close. In fact,
the automobile, which is but a locomotive that runs at will anywhere, is
the father of the greater machine.
About the beginning of 1800, self-propelled vehicles steamed along the
roads of Old England, carrying passengers safely, if not swiftly, and,
strange to say, continued to run more or less successfully until
prohibited by law from using the highways, because of their interference
with the horse traffic. Therefore the locomotive and the railroads
throve at the expense of the automobile, and the permanent iron-bound
right of way of the railroads left the highways to the horse.
The old-time automobiles were cumbrous affairs, with clumsy boilers, and
steam-engines that required one man's entire attention to keep them
going. The concentrated fuels were not known in those days, and
heat-economising appliances were not invented.
It was the invention by Gottlieb Daimler of the high-speed gasoline
engine, in 1885, that really gave an impetus to the building of
efficient automobiles of all powers. The success of his explosive
gasoline engine, forerunner of all succeeding gasoline motor-car
engines, was the incentive to inventors to perfect the steam-engine for
use on self-propelled vehicles.
Unlike a locomotive, the automobile must be light, must be able to carry
power or fuel enough to drive it a long distance, and yet must be almost
automatic in its workings. All of these things the modern motor car
accomplishes, but the struggle to make the machinery more efficient
still continues.
The three kinds of power used to run automobiles are steam, electricity,
and gasoline, taken in the order of application. The steam-engines in
motor-cars are not very different from the engines used to run
locomotives, factory machinery, or street-rollers, but they are much
lighter and, of course, smaller--very much smaller in proportion to the
power they produce. It will be seen how compact and efficient these
little steam plants are when a ten-horse-power engine, boiler,
water-tank, and gasoline reservoir holding enough to drive the machine
one hundred miles, are stored in a carriage with a wheel-base of less
than seven feet and a width of five feet, and still leave ample room for
four passengers.
It is the use of gasoline for fuel that makes all this possible.
Gasoline, being a very volatile liquid, turns into a highly inflammable
gas when heated and mixed with the oxygen in the air. A tank holding
from twenty to forty gallons of gasoline is connected, through an
automatic regulator which controls the flow of oil, to a burner under
the boiler. The burner allows the oil, which turns into gas on coming in
contact with its hot surface, to escape through a multitude of small
openings and mix with the air, which is supplied from beneath. The
openings are so many and so close together that the whole surface is
practically one solid sheet of very hot blue flame. In getting up steam
a separate blaze or flame of alcohol or gasoline is made, which heats
the steel or iron with which the fuel-oil comes in contact until it is
sufficiently hot to turn the oil to gas, after which the burner works
automatically. A hand air-pump or one automatically operated by the
engine maintains sufficient air pressure in the fuel-tank to keep a
constant flow.
Most steam automobile boilers are of the water-tube variety--that is,
water to be turned into steam is carried through the flames in pipes,
instead of the heat in pipes through the water, as in the ordinary flue
boilers. Compactness, quick-heating, and strength are the
characteristics of motor-car boilers. Some of the boilers are less than
twenty inches high and of the same diameter, and yet are capable of
generating seven and one-half horse-power at a high steam pressure (150
to 200 pounds). In these boilers the heat is made to play directly on a
great many tubes, and a full head of steam is generated in a few
minutes. As the steam pressure increases, a regulator that shuts off
the supply of gasoline is operated automatically, and so the pressure
is maintained.
[Illustration: THE "LIGHTHOUSE" OF THE RAIL
The switchman's house (on the left), commanding a view of the railroad
yard, from which the switches of the complicated system are worked and
the semaphore signals operated.]
The water from which the steam is made is also fed automatically into
the boiler, when the engine is in motion, by a pump worked by the engine
piston. A hand-pump is also supplied by which the driver can keep the
proper amount when the machine is still or in case of a breakdown. A
water-gauge in plain sight keeps the driver informed at all times as to
the amount of water in the boiler. From the boiler the steam goes
through the throttle-valve--the handle of which is by the driver's
side--direct to the engine, and there expands, pushes the piston up and
down, and by means of a crank on the axle does its work.
The engines of modern automobiles are marvels of compactness--so
compact, indeed, that a seven-horse-power engine occupies much less
space than an ordinary barrel. The steam, after being used, is admitted
to a coil of pipes cooled by the breeze caused by the motion of the
vehicle, and so condensed into water and returned to the tank. The
engine is started, stopped, slowed, and sped by the cutting off or
admission of the steam through the throttle-valve. It is reversed by
means of the same mechanism used on locomotives--the link-motion and
reversing-lever, by which the direction of the steam is reversed and the
engine made to run the other way.
After doing its work the steam is made to circulate round the cylinder
(or cylinders, if there are more than one), keeping it extra
hot--"superheated"; and thereafter it is made to perform a like duty to
the boiler-feed water, before it is allowed to escape.
All steam-propelled automobiles, from the light steam runabout to the
clumsy steam roller, are worked practically as described. Some machines
are worked by compound engines, which simply use the power of expansion
still left in the steam in a second larger cylinder after it has worked
the first, in which case every ounce of power is extracted from the
vapour.
The automobile builders have a problem that troubles locomotive builders
very little--that is, compensating the difference between the speeds of
the two driving-wheels when turning corners. Just as the inside man of a
military company takes short steps when turning and the outside man
takes long ones, so the inside wheel of a vehicle turns slowly while the
outside wheel revolves quickly when rounding a corner. As most
automobiles are propelled by power applied to the rear axle, to which
the wheels are fixed, it is manifest that unless some device were made
to correct the fault one wheel would have to slide while the other
revolved. This difficulty has been overcome by cutting the axle in two
and placing between the ends a series of gears which permit the two
wheels to revolve at different speeds and also apply the power to both
alike. This device is called a compensating gear, and is worked out in
various ways by the different builders.
The locomotive builder accomplishes the same thing by making his wheels
larger on the outside, so that in turning the wide curves of the
railroad the whole machine slides to the inside, bringing to bear the
large diameter of the outer wheel and the small diameter of the inner,
the wheels being fixed to a solid axle.
The steam machine can always be distinguished by the thin stream of
white vapour that escapes from the rear or underneath while it is in
motion and also, as a rule, when it is at rest.
The motor of a steam vehicle always stops when the machine is not
moving, which is another distinguishing feature, as the gasoline motors
run continually, or at least unless the car is left standing for a long
time.
As the owners of different makes of bicycles formerly wrangled over the
merits of their respective machines, so now motor-car owners discuss the
value of the different powers--steam, gasoline, and electricity.
Though steam was the propelling force of the earliest automobiles, and
the power best understood, it was the perfection of the gasoline motor
that revived the interest in self-propelled vehicles and set the
inventors to work.
A gasoline motor is somewhat like a gun--the explosion of the gas in the
motor-cylinder pushes the piston (which may be likened to the
projectile), and the power thus generated turns a crank and drives the
wheels.
The gasoline motor is the lightest power-generator that has yet been
discovered, and it is this characteristic that makes it particularly
valuable to propel automobiles. Santos-Dumont's success in aerial
navigation is due largely to the gasoline motor, which generated great
power in proportion to its weight.
A gasoline motor works by a series of explosions, which make the noise
that is now heard on every hand. From the gasoline tank, which is always
of sufficient capacity for a good long run, a pipe is connected with a
device called the carbureter. This is really a gas machine, for it turns
the liquid oil into gas, this being done by turning it into fine spray
and mixing it with pure air. The gasoline vapour thus formed is highly
inflammable, and if lighted in a closed space will explode. It is the
explosive power that is made to do the work, and it is a series of small
gun-fires that make the gasoline motor-car go.
All this sounds simple enough, but a great many things must be
considered that make the construction of a successful working motor a
difficult problem.
In the first place, the carbureter, which turns the oil into gas, must
work automatically, the proper amount of oil being fed into the machine
and the exact proportion of air admitted for the successful mixture.
Then the gas must be admitted to the cylinders in just the right
quantity for the work to be done. This is usually regulated
automatically, and can also be controlled directly by the driver. Since
the explosion of gas in the cylinder drives the piston out only, and
not, as in the case of the steam-engine, back and forward, some
provision must be made to complete the cycle, to bring back the piston,
exhaust the burned gas, and refill the cylinder with a new charge.
In the steam-engine the piston is forced backward and forward by the
expansive power of the steam, the vapour being admitted alternately to
the forward and rear ends of the cylinder. The piston of the gasoline
engine, however, working by the force of exploded gas, produces power
when moving in one direction only--the piston-head is pushed out by the
force of the explosion, just as the plunger of a bicycle pump is
sometimes forced out by the pressure of air behind it. The piston is
connected with the engine-crank and revolves the shaft, which is in turn
connected with the driving-wheels. The movement of the piston in the
cylinder performs four functions: first, the downward stroke, the result
of the explosion of gas, produces the power; second, the returning
up-stroke pushes out the burned gas; third, the next down-stroke sucks
in a fresh supply of gas, which (fourth) is compressed by the
following-up movement and is ready for the next explosion. This is
called a two-cycle motor, because two complete revolutions are necessary
to accomplish all the operations. Many machines are fitted with heavy
fly-wheels, the swift revolution of which carries the impetus of the
power stroke through the other three operations.
[Illustration: A GIANT AUTOMOBILE MOWER-THRASHER
This machine cuts a swath 35 feet wide and thrashes and sacks the grain
as it moves along. Seventy to 100 acres of grain a day are harvested by
this machine, and 1,000 to 1,500 sacks are produced each working day.]
To keep a practically continuous forward movement on the driving-shaft,
many motors are made with four cylinders, the piston of each being
connected with the crank-shaft at a different angle, and each cylinder
doing a different part of the work; for example, while No. 1 cylinder is
doing the work from the force of the explosion, No. 2 is compressing,
No. 3 is getting a fresh supply of gas, and No. 4 is cleaning out waste
gas. A four-cylinder motor is practically putting forth power
continuously, since one of the four pistons is always at work.
While this takes long to describe, the motion is faster than the eye can
follow, and the "phut, phut" noise of the exhaust sounds like the tattoo
of a drum. Almost every gasoline motor vehicle carries its own electric
plant, either a set of batteries or more commonly a little magneto
dynamo, which is run by the shaft of the motor. Electricity is used to
make the spark that explodes the gas at just the right moment in the
cylinders. All this is automatic, though sometimes the driver has to
resort to the persuasive qualities of a monkey-wrench and an oil-can.
The exploding gas creates great heat, and unless something is done to
cool the cylinders they get so hot that the gas is ignited by the heat
of the metal. Some motors are cooled by a stream of water which, flowing
round the cylinders and through coils of pipe, is blown upon by the
breeze made by the movement of the vehicle. Others are kept cool by a
revolving fan geared to the driving-shaft, which blows on the cylinders;
while still others--small motors used on motor bicycles, generally--have
wide ridges or projections on the outside of the cylinders to catch the
wind as the machine rushes along.
The inventors of the gasoline motor vehicles had many difficulties to
overcome that did not trouble those who had to deal with steam. For
instance, the gasoline motor cannot be started as easily as a
steam-engine. It is necessary to make the driving-shaft revolve a few
times by hand in order to start the cylinders working in their proper
order. Therefore, the motor of a gasoline machine goes all the time,
even when the vehicle is at rest. Friction clutches are used by which
the driving-shaft and the axles can be connected or disconnected at the
will of the driver, so that the vehicle can stand while the motor is
running; friction clutches are used also to throw in gears of
different sizes to increase or decrease the speed of the vehicle, as
well as to drive backward.
[Illustration: AN AUTOMOBILE BUCKBOARD]
The early gasoline automobiles sounded, when moving, like an artillery
company coming full tilt down a badly paved street. The exhausted gas
coughed resoundingly, the gears groaned and shrieked loudly when
improperly lubricated, and the whole machine rattled like a runaway
tin-peddler. Ingenious mufflers have subdued the sputtering exhaust, the
gears are made to run in oil or are so carefully cut as to mesh
perfectly, rubber tires deaden the pounding of the wheels, and carefully
designed frames take up the jar.
Steam and gasoline vehicles can be used to travel long distances from
the cities, for water can be had and gasoline bought almost anywhere;
but electric automobiles, driven by the third of the three powers used
for self-propelled vehicles, must keep within easy reach of the charging
stations.
Just as the perfection of the gasoline motor spurred on the inventors to
adapt the steam-engine for use in automobiles, so the inventors of the
storage battery, which is the heart of an electric carriage, were
stirred up to make electric propulsion practical.
The storage battery of an electric vehicle is practically a tank that
holds electricity; the electrical energy of the dynamo is transformed
into chemical energy in the batteries, which in turn is changed into
electrical energy again and used to run the motors.
Electric automobiles are the most simple of all the self-propelled
vehicles. The current stored in the batteries is simply turned off and
on the motors, or the pressure reduced by means of resistance which
obstructs the flow, and therefore the power, of the current. To reverse,
it is only necessary to change the direction of the current's flow; and
in order to stop, the connection between motor and battery is broken by
a switch.
Electricity is the ideal power for automobiles. Being clean and easily
controlled, it seems just the thing; but it is expensive, and sometimes
hard to get. No satisfactory substitute has been found for it, however,
in the larger cities, and it may be that creative or "primary" batteries
both cheap and effective will be invented and will do away with the one
objection to electricity for automobiles.
The astonishing things of to-day are the commonplaces of to-morrow, and
so the achievements of automobile builders as here set down may be
greatly surpassed by the time this appears in print.
The sensations of the locomotive engineer, who feels his great machine
strain forward over the smooth steel rails, are as nothing to the almost
numbing sensations of the automobile driver who covered space at the
rate of eighty-eight miles an hour on the road between Paris and Madrid:
he felt every inequality in the road, every grade along the way, and
each curve, each shadow, was a menace that required the greatest nerve
and skill. Locomotive driving at a hundred miles an hour is but mild
exhilaration as compared to the feelings of the motor-car driver who
travels at fifty miles an hour on the public highway.
Gigantic motor trucks carrying tons of freight twist in and out through
crowded streets, controlled by one man more easily than a driver guides
a spirited horse on a country road.
Frail motor bicycles dash round the platter-like curves of cycle tracks
at railroad speed, and climb hills while the riders sit at ease with
feet on coasters.
An electric motor-car wends the streets of New York every day with
thirty-five or forty sightseers on its broad back, while a groom in
whipcord blows an incongruous coaching-horn in the rear.
Motor plows, motor ambulances, motor stages, delivery wagons,
street-cars without tracks, pleasure vehicles, and even baby carriages,
are to be seen everywhere.
In 1845, motor vehicles were forbidden the streets for the sake of the
horses; in 1903, the horses are being crowded off by the motor-cars. The
motor is the more economical--it is the survival of the fittest.
[Illustration: AN AUTOMOBILE PLOW
A form of automobile that can be applied to all sorts of uses on the
farm.]