Figure 4-71. Pressure Box.
weights in a normally closed position. The governor
Section VII. 4-32.Purpose.Governors are used on motive
weights must reach sufficient speed as the engine
vehicles to regulate maximum engine speed and thus
rotates to develop enough centrifugal force to overcome
prevent excess engine wear. Testing has proven that
the force of the spring before they swing out to operate
the rate of engine wear increases by the square of
the throttle valve. This means that the spring tension
engine speed. This means that in the higher speed
regulates engine speed. An adjustment is provided to
ranges even a few hundred rpm speed increase will
adjust the governed engine speed. The adjustment is in
cause a tremendous wear increase.
the form of a screw that increases or decreases spring
describes the various types of governors.
4-33. Centrifugal Governors (Fig. 4-72).
4-34. Velocity-Vacuum Governor.
centrifugal governor is made up of two weighted arms
vacuum govenor is operated by the speed of the air-fuel
pivoted on a spindle. The spindle and the arms are
mixture passing the throttle plate. As the speed of the
rotated by the engine through a drive shaft. The weights
air-fuel mixture reaches a certain point, it will tend to
tend to swing outward from their center axis as they
push the throttle valve closed. This effectively will limit
rotate. The outward movement of the weights will,
engine speed. In order for this to take place, the throttle
through linkage, close an extra throttle valve that is
shaft must be offset in the carburetor throat so that the
installed in the carburetor throat. The operation of this
throttle valve effectively will restrict engine speed. There
is a spring installed on the governor that holds the