Great Falls High School - Roundup Yearbook (Great Falls, MT)

Page 13 text:

THIRD YEAR JUNE, 1910 NUMBER FOUR The Motor Car DespilL the large number of aulomobiles in use today, there are many boys and g ' irls who don ' t know where and how the power is developed that sends the machine along; and how it is connected or transmitted to the (h ' iving wheels. There are steam and electric cars, but the gasoline engine is the most common source of power for the self-propelled vehicle. Ihe engine is mounted just l)acA of the front axle. It may have one, two, four, six or more cylinders, casted separatel} ' , in pairs or all together. A cylinder is made of cast steel, say five inches in diameter and seven inches long, closed at one end. All six cylinders of a six-cylinder en- gine work the same as one, so the latter will be descrd ed here. The cylinder has four openings. The intake part, where the ex- plosive mixture is let into the cylinder; the exhaust part, where the burned gases go out ; one for the spark plug and one for a small pet cock, used to put gasoline or lubricating oil into the cylinder. This valve is sometimes opened when starting so as to make it easy to turn the crank. The piston is an iron plunger that fits snugly in the cylinder. The piston rod connects the piston with the crank on the main shaft. The main shaft, with cranks, is enclosed by a casing of alumnium or iron. By a set of gears run l y the engine itself there is a smaller shaft made to revolve once while the main shaft, to which is attached the fly-wheel, makes the revolutions. On this two-to-one shaft, as it is called, are mounted two small solid wheels about an inch and a half in diameter, having a large bump on the circumference, called cains. Running on these cams are two other small uniform solid wheels, whose axles are connected to the valve stems, which are rods of iron about five-eighths of an inch in diameter. Fastened on the upper ends of these valve stems or rods are the valves, which close or open the intake and exhaust openings of the cylinder at the right instant. When the cams on this two-to-one come around to a certain posi- tion, they push open the valve, thus allowing the new mixture to be taken in or the old gase to be pushed otit, depending on which valve It is. These valves are opened once every two revolutions of the ma n shaft but not at the same time. The intake valve is opened when the piston starts down after the exhaust stroke and closes when it starts up. The exhaust valve is opened when the piston is about half through the power stroke, and closes when the piston starts on the intake stroke.