Fig. 35.—“Oil-Pull” Fuel System
These air cleaners must be emptied frequently, for if they are not kept clean it cannot be expected that they will do their work.
A tractor engine is built to develop its maximum power at a certain speed; if it runs at greater speed, it will not operate efficiently, and there will be unnecessary wear of its parts. These engines are therefore usually fitted with governors which hold them at their most efficient speed. A governor operates by centrifugal force.
Anything in motion tries to move in a straight line; if it is forced to move in a circle, it will exert force in trying to move away from its center. It is this that is called centrifugal force. It is centrifugal force that holds water in a pail that is being swung around the head, and that makes the pail fly off if it is released.
Fig. 36.—Air Washer
In applying this principle to a governor, weights are attached to a plate and made to revolve; springs hold them together, but in spite of this, centrifugal force throws them outward. In moving, they act on a rod that operates the throttle; as the speed increases, the move outward more and more, and it is a simple matter of adjustment to cause them to close the throttle when the speed reaches a desired point.
Fig. 37.—Air Strainer
