| 摘要 |
PROBLEM TO BE SOLVED: To provide a composite pressurization two-stage jack used when a heavy weight is lifted up. SOLUTION: The composite pressurization two-stage hydraulic jack is constituted such that a second cylinder 2 is provided so as to be superposed on an outer peripheral wall of a central cylinder 3, the second cylinder and a piston 5 of the central cylinder are bonded, and force for lifting up it by an oil pressure is synthesized and increased. Further, a third cylinder 1 for lifting up the second cylinder is provided, the lifted up height is raised at two stages, a second piston 4 provided in the piston of the central cylinder is simultaneously bonded to the third cylinder to be made to an upper limit stopper, a relief valve 12 for pressurization oil is provided such that excessive stress by an oil pressure of the pressure larger than it is not applied to a body at upper limit. COPYRIGHT: (C)2008,JPO&INPIT
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