CHAPTER XXXVIII
Engines; Motors and Batteries; Fuels
267. Gasoline Engines. A gasoline engine (Fig. 151) should be operated out of doors or in a well-ventilated room, except in cases where the exhaust pipe is carried thru the wall of the building to the outside. The fumes may cause illness, or even death, to any one staying in the room.
A gasoline engine should be mounted on a substantial base of concrete or heavy timbers, or on a well-built truck, and should be put in good order before the woman or girl begins to use it. The engine must be level. If more than one device is attached to it, be sure to use the right pulleys on the engine and the machine to be operated. An engine is usually equipped with pulleys of two or more sizes. The size of the wheel on the washing machine or vacuum cleaner must be of a size to make the desired number of revolutions per minute.
268. Figuring Speed of Pulleys. For example, if the speed of the engine is 425 revolutions per minute and the diameter of the pulley on the engine is 12 inches, and the machine is to be run at 150 revolutions per minute, have a pulley on the machine of a diameter which equals 425 times 12, or 5,100 divided by 150, or 34 inches.
It would be more convenient to have a smaller pulley on this machine. Since there is a smaller wheel on the engine which, we will say, is 6 inches in diameter, put the belt on the smaller wheel, and then a wheel only 17 inches in diameter will be needed on the machine.
Fig. 151. Sectional view of gasoline engine.