To provide a speed control device for a hydraulic actuator improving efficiency of the actuator by subdividing pressure setting of the actuator and adjusting rotation speed in multi stages, and improving durability by breaking up overload acting on the actuator at a time of high speed rotation.
This device includes a direction switching valve 2 provided in an oil passage between an hydraulic pressure source and an actuator 1 and controlling direction of flow of hydraulic fluid supplied to the actuator 1, an inclined piston 3 provided between the actuator 1 and a parallel oil passage 5 connected to a supply side oil passage of the actuator in parallel and controlling inclination angle of an inclined plate of the actuator, a multi stage adjustment piston 6 installed inside of the actuator 1 or attached on an outer part driven at a time of hydraulic fluid supply to adjust inclination angles of inclined plate of the actuator 1 in multi stage, and a multi stage adjustment control valve 7.
Hideo Shimizu
Yuichi Takagi
Kazuki Hidaka
Tomoko Watanabe
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