An increase in the speed of propeller 1, driven by the aircraft engine, increases the speed of disk 2, moving weights 3 outward an shifting valve spool 4 upward. Fluid from the valve is delivered to the cylinder of servomotor 5 whose piston is fixed. This moves the cylinder axially to the right and, by means of pins b, guide lugs a on the cylinder turn the blades of propeller 1 about their axes to increase the propeller pitch. This reduces the engine (and propeller) speed. Upon a reduction in propeller speed, spring 7 shifts valve spool 4 downward, spring 6 forces the fluid out of the cylinder of servomotor 5 and moves the cylinder to the left, reducing the pitch of the propeller and increasing the engine (and propeller) speed.
$4266$CHP,Rg$