| 摘要 |
Disclosed is an apparatus comprising a hydraulic cylinder assembly, a load connected to the cylinder, a reversible hydraulic pump assembly, a pressurized supply of hydraulic fluid, first and second conduits for hydraulic fluid, and a control system. The hydraulic cylinder assembly comprises a cylinder sealed by an upper head and a lower head and carrying a piston which divides the hydraulic cylinder assembly into an upper chamber and a lower chamber. The load is connected to the piston and urges it toward the lower head. The first conduit for hydraulic fluid connects the reversible hydraulic pump assembly in fluid flow communication with the lower chamber of the hydraulic cylinder assembly. The second conduit for hydraulic fluid connects the reversible hydraulic pump assembly in fluid flow communication with the pressurized supply of hydraulic fluid. The control system is operably associated with the reversible hydraulic pump assembly to cause hydraulic fluid to flow back and forth between the lower chamber of the hydraulic cylinder assembly and the pressurized supply of hydraulic fluid.
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