| 摘要 |
In an industrial, agricultural, or earth-moving vehicle, a charging pump, which delivers hydraulic fluid under pressure remaining substantially constant while the vehicle is operating and a coupler are combined. In the coupler, a hydraulically actuated piston-cylinder mechanism is used to wedge a pin into an orifice in an implement, thereby to couple the implement to the vehicle, and to withdraw the pin, thereby to uncouple the implement from the vehicle. A directional valve, which is connected between the pump and the piston-cylinder mechanism, is switchable by an operator of the vehicle between a first stage wherein the directional valve allows hydraulic fluid delivered by the pump to actuate the piston-cylinder mechanism in a forward direction, thereby to wedge the pin into the orifice, and a second stage wherein the directional valve allows hydraulic fluid delivered by the pump to actuate the piston-cylinder mechanism in a reverse direction, thereby to withdraw the pin. A normally closed, pilot actuated check valve, which is connected between the directional valve and the piston-cylinder mechanism, checks flow of hydraulic fluid from the piston-cylinder mechanism to the directional valve when and while the check valve is closed but allows such flow when and while the check valve is opened. The check valve is arranged to be closed when and while the directional valve is switched to the forward stage but to be opened by hydraulic fluid delivered by the pump when and while the directional valve is switched to the reverse stage.
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