Patent ID: 6511292
Filing Date: 2003-01-28
Classification: B64C

Abstract:
A variable pitch propeller system comprising:a rotatable propeller hub adapted to be driven by a prime mover; a double acting piston carried by said hub; propeller blades having shanks journaled on said hub; a linkage connecting said piston to said shanks so that movement of said piston will cause rotation of said shanks within said hub; a transfer bearing for providing first and second streams of hydraulic fluid under pressure, said first stream adapted to be applied to one side of said piston and said second stream being adapted to be applied to the opposite side of said piston; a main control for regulating the pressures of said first and second streams to set the pitch of said blades on said hub; and a backup governing system carried by said hub and hydraulically interposed between said main control and said piston and including a metering valve including a metering valve member movable between a plurality of metering positions, first and second, opposing biasing elements applying oppositely directed biasing forces to said valve member, a flyweight assembly connected to said valve member applying a speed dependent valve positioning force to said valve member in opposition to said first biasing element and in addition to said second biasing element, an actuator operatively associated with said second biasing element and operable to change the bias applied by said second biasing element to said valve member, a first stream control valve connected to said actuator and interposed between said transfer bearing and said piston and operable to control the flow of said first stream to said piston one side.