Abstract: A propeller system has a pair of hub assemblies driven in counter-rotation, each hub assembly having a mechanical pitch change actuator, each actuator being provided with a pitch lock that rotates simultaneously with the motion of the actuator to allow the actuator to set propeller blade pitch, but locks the propeller blade positionally when not rotating simultaneously with the actuator, and a differential for transmitting a pitch change signal across a rotating gap between the two hub assemblies and for providing power to a means for providing the pitch change signals. A pair of motors provide the rotative signal to set the pitch of the blades in each hub assembly. One of the pair of motors drives the actuator towards high pitch and the other motor drives the actuator towards low pitch. A synchronizer coordinates the signals of the first and second motors so that a pitch lock moves simultaneously with the actuator.

Abstract: A modular, easily replaceable, pitch actuation system is removably secured within the hub of an aircraft. The modular system houses a driving system which provides a rotational output to set the pitch of propeller blades mounted to the hub, and a pitch changing system that controls the driving system. The driving system includes a high-speed, low-torque hydraulic motor that drives an harmonic drive to amplify the torque of the motor. The pitch changing system includes an actuator which positions a valve that controls the hydraulic motor, and a nulling gear which repositions the valve and acts as a pitch lock.

Abstract: A system (10) of parallel hydraulic actuators (15) and (20) includes a pair of laterally spaced, longitudinally extending, discrete feedback levers (180) and (185) which independently provide feedback signals to a pair of actuator control valves (50) and (55) with enhanced accuracy and minimal lateral loading of the system.

Abstract: A pitch control system for a multibladed variable pitch wind turbine. Each of the turbine blades is pivotally driven about the longitudinal axis thereof independently of the other blades by at least a pair of hydraulic actuators. The actuators are supplied with pressurized hydraulic fluid from a first source thereof under conditions of normal pitch change adjustment. Under conditions wherein feathering of the blades is required, the actuators are supplied with hydraulic fluid from second sources thereof such that one of the actuators associated with each of the blades is supplied with fluid from one second source and a second actuator is provided with fluid from a redundant second source whereby blade feathering may be effected despite a malfunction of one of the redundant sources or one of the actuators.

Abstract: Where a single output gear is driven from a single input pinion through a pair of idler gears and equal torque division between the two idlers is accomplished by floating the input pinion between the two idlers in a yoke that is hinged to the gear housing by spaced hinge pins. One hinge pin is located on the resultant load line from the points where the pinion meshes with the idlers and the other pin has a small clearance to allow the yoke to pivot about the first or loaded pin. Lubrication by oil under pressure for both pins assures a damping action at the loose pin.

Abstract: A pitch-change apparatus for a ducted thrust fan having a plurality of variable pitch blades employs a camming ring mounted coaxially of the hub at an axially fixed station along the hub axis for rotation about the hub axis both with the blades and relative to the blades. The ring has a generally spherical outer periphery and a plurality of helical camming grooves extend in a generally spherical plane on the periphery. Each of the variable pitch blades is connected to a pitch-change horn having a cam follower mounted on its outer end, and the camming ring and the horns are so arranged about the hub axis that the plurality of followers on the horns engage respectively the plurality of helical camming grooves. Rotary drive means receives pitch-change commands from an appropriate controller and rotates the camming ring relative to the blades to cause blade pitch to be changed through the cooperative operation of the camming grooves on the ring and the cam followers on the pitch-change horns.

Abstract: This invention cures the problem attendant the ingestion of oil in the engine of a fan-turbine engine combustion propulsor should oil leak from the fan blade seal by capturing and judiciously venting the leakage.