Abstract: A redundant control actuation system (100) provides hydraulic logic cross-coupling between physically-separate servoactuators (101A, 101B). Each servoactuator has a control valve (102A, 102B) arranged to provide a hydraulic output in response to a control signal. Each actuator also has a hydraulic actuator (106A, 106B) arranged to move a load in response to the hydraulic output from its associated control valve. Logic valve means (103A, 104A, 105A, 103B, 104B, 105B) are operatively associated with the control valves (102A, 102B) and actuators (106A, 106B). Each logic valve means is supplied with hydraulic and electrical input signals.

Abstract: A redundant control actuation system (100) provides hydraulic logic cross-coupling between physically-separate servoactuators (101A, 101B). Each servoactuator has a control valve (102A, 102B) arranged to provide a hydraulic output in response to a control signal. Each actuator also has a hydraulic actuator (106A, 106B) arranged to move a load in response to the hydraulic output from its associated control valve. Logic valve means (103A, 104A, 105A, 103B, 104B, 105B) are operatively associated with the control valves (102A, 102B) and actuators (106A, 106B). Each logic valve means is supplied with hydraulic and electrical input signals.

Abstract: A seal assembly is arranged to contain leakage of hydraulic fluid passing between a wall opening and a penetrant rod portion passing through the opening. The seal assembly includes a sliding-seal member mounted on a portion of the rod for sliding movement toward and away from an abutment surface and a non-sliding flexible-seal member arranged between the body and the sliding-seal member. The body, flexible-seal member, sliding-seal member and rod define a sealed chamber into which such fluid will leak. The chamber communicates with a fluid reservoir through a oneway check valve. The sliding-seal and flexible-seal members are arranged in parallel with one another. In one embodiment, a spring urges the sliding-seal member to move toward an abutment surface provided on the rod. In another embodiment, movement of the sliding-seal member relative to the body is limited by facing abutment steps.