| 摘要 |
PROBLEM TO BE SOLVED: To certainly realize an elongation operation by a hydraulic action, and to enable permanent securement of a contraction operation by air spring force. SOLUTION: This hydraulic jack comprises a ram body 3 that is retractably inserted into a cylinder section 2 drilled in a housing 1 and can be lifted up or down with respect to the housing 1. The ram body 3 rises when oil pressure is supplied from the outside to a pressure chamber R1 partitioned in the cylinder section 2 with the ram body 3. The ram body 3 lowers by supply of oil pressure to a back pressure chamber R2 partitioned by the ram body 3 in the cylinder section 2 under release of the supply of the oil pressure to the pressure chamber R1. An accumulator 8 allowing supply or discharge of the oil pressure to the back pressure chamber R2 is provided. COPYRIGHT: (C)2005,JPO&NCIPI
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