| 摘要 |
A hydraulic arrangement for use in dockboard installations which include a hydraulic cylinder for raising the dockboard. The arrangement allows the dockboard to be raised to a position above the vehicle platform, and then to be lowered onto the vehicle platform, all by a single operation of a switch which energizes the hydraulic pump motor. The hydraulic arrangement includes a special control valve situated between the pump and hydraulic cylinder, the valve being also connected to a reservoir, and arranged so that when the pump is operating at normal pressure the control valve allows fluid to flow to the cylinder so raising the dockboard, and when the pump motor is stopped the control valve allows fluid to flow from the cylinder to the reservoir allowing lowering of the dockboard. The circuit includes further valve means to assist reduction of pressure at the pump outlet when the pump motor is stopped, to speed operation of the valve.
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