HOW AUTOMOBILES WORK
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.
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.