Abstract: A pitch change actuation system is disclosed for adjusting the pitch of a variable pitch propeller blades (120) operatively connected for pitch change to a pitch change actuator piston (140). A pitch change control system (10) is operatively connected to the pitch change actuator piston (140) for selectively pressuring the pitch change actuator piston to effectuate a desired change in the pitch of the propeller blades (120). The pitch change control system (10) comprises a primary electrohydraulic valve (30), a protection valve (60), an electronic controller (20) and a protection solenoid (50). During normal operation, the primary electrohydraulic valve (30) is modulated under control of the electronic controller (20) to effect pitch change.

Abstract: A pitch change actuation system is disclosed for adjusting the pitch of a variable pitch propeller blade (20) rotatably mounted to a hub (10) of the propeller. The pitch change actuator comprises a blade actuation piston (30) operatively connected to the propeller blade (20), a pitchlock piston (50) having a longitudinally directed annular shaft (56) extending therefrom about the shaft (34) of the blade actuation piston (30), pitchlock assembly (130, 140, 150) operatively interconnected between the pitchlock piston (50) and the blade actuation piston (30) for restraining inadvertent blade pitch reduction, bias spring (60) for exerting a preload force against the pitchlock piston (50), and fluid supply conduit (70) operatively interconnected in fluid communication between control valve (100) and the pitch change actuator.

Abstract: A pitch control system has a main electronic control, a mechanical back-up control and a switching system for transferring pitch control from the electronic to the mechanical control in the event of electronic control failure. The switching system utilizes a switch for comparing the output of the electronic and mechanical control systems, the switch choosing the mechanical system if a failure occurs in the electronic control system. In certain failure modes, an enable solenoid simultaneously locks out the switch, to ensure mechanical pitch change control, and resets the mechanical back-up control to provide a lower degree of pitch control than conventional back-up controllers.

Abstract: A self-locking pitch change actuator is configured to fit within an annular hub (34). A ring gear (40) is driven circumferentially by a tangentially oriented ballscrew (42) and traveler (44). The ballscrew (42) is driven by a hydraulic motor (50) controlled responsive to an electric pitch change motor (74). A pitchlock (62) is positioned by the collective actions of the ballscrew (42) and pitch change motor (74), with any movement relative to a preselected null position driving the hydraulic motor beta control valve (60) into an operative position.

Abstract: An easily manipulable camming mechanism is disposed within a cavity designed to hold a standard nuclear biological filter within an environmentally sealed military vehicle. The camming mechanism utilizes a cammed actuator to transfer a motive force to a spring which urges a piston to engage or disengage an inlet or an outlet of the filter. The spring ensures that seals on the filter are compressed to the proper force and absorbs excessive torque which might damage the filter or the mechanism.

Abstract: A missile (10) and concepts for deploying the fins (14) thereof from a stored to a deployed position are disclosed. One device described has three main portions including: A first end portion (32) housing an initiator (22) that powers the device and a locking mechanism (26) that holds the fin at its stored and its locked position; a central portion (34) housing a driven piston (24) that rotates a positively connected fin (14) from the stored to the deployed position; and, a second end portion (36) housing a damping system that controls the rate of deployment of the fins.

Abstract: In a propeller pitch control system, a selector 10 isolates engine (42) speed control in one of two engine governor (175 and 300) systems. The selector is input with fluid pressure signals from a pair of pilot valves (215 and 325), each operated by a corresponding one of the governors. The selector passes the signal of lowest magnitude to an actuator 40 which sets blade pitch in accordance with the magnitude of the signal whereby the governor providing such signal (through its associated pilot valve) controls engine speed independently of the other governor.

Abstract: A pitch control system (10) for a variable pitch propeller effects engine governor (330), control of blade pitch under normal operating conditions and automatically effects direct (beta) control of blade pitch by the power lever (305) throughout a predetermined range of power lever settings. The system is hydromechanical and comprises a pitch actuator (40) and a pair of control valves (120 and 210), a first of the valves (120) applying a metered fluid pressure from a governor controlled pilot valve to the actuator and blocking that signal and replacing it with a supply fluid pressure at the point of transition from governor to beta control. The second control valve (210) effects a controlled draining of the actuator and connection thereof with the power lever (305).

Abstract: A propeller pitch control system having a mechanical low pitch stop which includes an electrical backup therefor. The backup comprises an electrically operatable means (245) to effect blade pitch adjustment toward feather under conditions of failure of the low pitch stop indicated by propeller operation at pitch angles in the range of beta operation, but power settings in the range of normal engine speed governor pitch control. Such operating conditions actuate a pair of switches (190 and 195) connecting the means (245) to a voltage source to increase blade pitch toward feather, thereby preventing overspeed operation of the propeller.

Abstract: A propeller pitch change actuation system comprises an input actuator (230) driving a ball screw (200). Operation of the ball screw rotates a torque tube (140) about the longitudinal axis thereof to drive a screw 145 and control valve 120 which controls the pressurization of pitch change actuator (87). Actuator (87) is supplied with hydraulic fluid through the interior of the torque tube.