| 摘要 |
A hydraulic lock-out device for use with a hydraulic motor or jack that permits smooth operation of the piston and ram of the hydraulic motor during the working stroke and return stroke without surging or interruptions, and is operative to isolate the hydraulic motor from the fluid system when the ram is still and under load. A check valve associated with a first chamber of the device is operable to admit fluid under pressure to a first end of the hydraulic cylinder to move the piston from the first end toward the second end of the cylinder during a working stroke. A second valve associated with a second chamber of the device admits fluid to the second end of the cylinder for the return stroke of the piston and ram. Introduction of hydraulic fluid under pressure into the second chamber of the device is operable to move an actuating plunger and stem in the first chamber to open the first check valve to permit flow of hydraulic fluid from the first end of the hydraulic cylinder during the return stroke of the hydraulic piston. The permissible rate of flow of hydraulic fluid from the second valve to the second end of the hydraulic cylinder is not substantially influenced by the position of the first valve such that surging and pulsations are eliminated during the return stroke of the hydraulic piston in the hydraulic cylinder. When the hydraulic ram is still and under load, the first check valve is closed to isolate or lock-out the hydraulic motor from the fluid system.
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