Failsafe valve for geared rotary actuator

An actuation system for displacing a movable member relative to a fixed member, the movable member having a failsafe position and being displaceable away from the failsafe position, the actuation system comprising:

• an actuator connecting the movable member to the fixed member;
• a hydraulic system having a hydraulic supply line, a first hydraulic control line, a second hydraulic control line, and a hydraulic return line;
• a hydraulic rotary motor powered by the hydraulic system and arranged to drive the actuator to displace the movable member relative to the fixed member, the hydraulic rotary motor including a first control port in hydraulic communication with the first hydraulic control line, a second control port in hydraulic communication with the second hydraulic control line, and a return port in hydraulic communication with the hydraulic return line;
• and
• a failsafe valve in hydraulic communication with the hydraulic system and the hydraulic rotary motor, the failsafe valve being operably connected to the movable member;
• wherein the failsafe valve has a non-activated state when hydraulic pressure in the hydraulic supply line is greater than or equal to a predetermined normal pressure and an activated state when hydraulic pressure in the hydraulic supply line is less than the predetermined normal pressure;
• wherein, when the failsafe is in the non-activated state, the first hydraulic control line is in hydraulic communication with the first control port of the hydraulic rotary motor, the second hydraulic control line is in hydraulic communication with the second control port of the hydraulic rotary motor, and the return port of the hydraulic rotary motor is in hydraulic communication with the hydraulic return line, such that the hydraulic rotary motor operates normally;
• wherein, when the failsafe valve is in the activated state and the movable member is away from the failsafe position, the first hydraulic control line and the first control port of the hydraulic rotary motor, or the second hydraulic control line and the second control port of the hydraulic rotary motor, are in hydraulic communication with the hydraulic return line.