THE COOLING SYSTEM
In order to prevent the walls of the cylinder from becoming red hot, it is necessary to cool them by some means, and this is done by surrounding the cylinder with a water jacket through which the cooling water is circulated.
Fig. 31—A Diagram showing piping and direction of circulation in a One-cylinder Water-cooled Motor.
In order to prevent the water from boiling and evaporating, thus making the constant addition of water necessary, a radiator is introduced into the system. This radiator is made up of very thin tubes which give up their heat rapidly, thereby keeping the temperature of the water below the boiling point. A fan is also used sometimes to draw the air through between the tubes, thereby making the process of cooling take place more rapidly. The system is so arranged that the water is drawn from the lower part of the radiator where the water is coldest by means of a pump and forced up through the water jackets and back into the radiator again. Several different styles of pumps are used, but a very common one is the gear pump shown in Fig. 32. As you will see by the drawing, it consists of two gears en mesh with each other which revolve in the direction indicated by the arrow. The water entering through the inlet pipe is drawn around the outside and forced out through the outlet at the top.
Fig. 32—A Gear Water Pump.
Fig. 33—Front End of Motor, showing radiator, fan and cam shaft gears.
