| 摘要 |
A system for handling gates and the like including a dual-effect hydraulic actuator with a stem traversing one of its chambers and a supply circuit controlled with oil which alternately moves the oil between the actuator chambers for an 'opening' or 'closing' movement. The circuit includes a pump for transfer of the oil between the chambers through piloted locking one-way valves, an oil tank and two one-way suction valves each connected between the tank and one of the two sides of the pump for allowing suction from the tank of the lacking oil. The suction valve connected from the side of the pump opposite the actuator chamber not traversed by the stem is a one-way valve controlled in such a manner as to open thanks to an overpressure on the hydraulic circuit branch which is for supply of the actuator chamber traversed by the stem. In this manner the oil in excess during movement of the actuator which is caused by transfer of the oil from the stemless chamber to the chamber with stem is dumped into the tank.
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