The Power behind the Engine
Automobiles have been largely responsible for the gas engine. To carry coal for fuel and water for steam would be impracticable for most motor cars. Electricity is used in some cars, but the batteries are heavy, expensive, and short-lived, and are not always easily replaceable. For this reason gasoline is extensively used, and in the average automobile the source of power is the force generated by exploding gases.
It was discovered some years ago that if the vapor of gasoline or naphtha was mixed with a definite quantity of air, and a light was applied to the mixture, an explosion would result. Modern science uses the force of such exploding gases for the accomplishment of work, such as running of automobiles and launches.
In connection with the gasoline supply is a carburetor or sprayer, from which the cylinder C
receives a fine mist of gasoline vapor and air. This mixture is ignited by an automatic, electric sparking device, and the explosion of the gases drives the piston P
to the right. In the 4-cycle type of gas engines - the kind used in automobiles - the four strokes are as follows: 1. The mixture of gasoline and air enters the cylinder as the piston moves to the right. 2. The valves being closed, the mixture is compressed as the piston moves to the left. 3. The electric spark ignites the compressed mixture and drives the piston to the right. 4. The waste gas is expelled as the piston moves to the left. The exhaust valve is then closed, the inlet valve opened, and another cycle of four strokes begins.
The use of gasoline in launches and automobiles is familiar to many. Not only are launches and automobiles making use of gas power, but the gasoline engine has made it possible to propel aŽroplanes through the air.
FIG. - The gas engine.