Hartzell HC-82XF-1 Owner's Manual page 56

Propeller Owner's Manual
175
A governor is an engine speed-sensing device that maintains
a constant engine/propeller RPM by changing blade angle
and varying load on the engine.
The governor uses an internal pump that is driven by an
accessory drive from the engine. This pump uses engine
lubricating oil and increases the engine oil pressure for
supply to the propeller. Engine speed sensing hardware
within the governor controls the supply of oil to, or drain of
oil from the propeller, resulting in a change of blade pitch to
maintain constant engine speed.
Oil pressure from the engine-driven governor is supplied to
the propeller mounted hydraulic cylinder through the engine
shaft and propeller hub. Increasing the oil volume within the
hydraulic cylinder decreases blade angle to increase engine
RPM. Decreasing the oil volume increases blade angle to
decrease engine RPM. By changing the blade angle, the
governor maintains constant engine RPM (within limits),
independent of the throttle setting.
If oil pressure is lost at any time, the summation of propeller
forces that is in direct opposition to the lost variable hydraulic
force will increase blade angle.
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DESCRIPTION AND OPERATION
Dec/05