| 摘要 |
A fluid flow control valve system to be used to control a hydraulic lifting mechanism used on elevators and the like. The valve system includes an inlet conduit from the pump and an inlet-outlet to and from a jack connected together by a conduit with a one-way valve operable in the direction from the pump to the jack, a first by-pass chamber connected to the pump side of the one-way valve and a second by-pass chamber connected to the jack side of said one-way valve, outlets to the pump sump from each by-pass chamber, and a movable gate control mechanism for controlling the exit of pressurized fluid from the first by-pass chamber or the second by-pass chamber through the outlets to the pump sump. Hydraulic fluid from the pump when the first chamber is sealed, passes through the one-way check valve. When the second chamber is also sealed, the fluid will provide pressure to a jack to lift a load. With the first chamber gate opened at least a portion or all of the fluid passes back to the sump. This slows or stops the fluid flow to the jack. The jack cannot lower because the gate control mechanism to the second chamber is closed. When the second chamber gate opening in the chamber connected to the jack is opened, the weight of the load puts pressure on the fluid forcing it to be discharged through the chamber back to the tank or sump. This lowers the load.
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