摘要 |
A hydraulic cylinder (4) moves a rod (3) in the direction of the axial center. The interior of a casing member (2) has an annular pressure booster (7) for pressurizing the oil in an external hydraulic chamber (6). The casing member (2) has a pressurized oil feed port (27) for feeding pressurized oil to the rod-moving hydraulic cylinder (4) and the input oil chamber (16) of the pressure booster (7). A throttle valve (8) is interposed in an oil supply channel extending from the pressurized oil feed port (27) to the input oil chamber (16). An oil discharge channel, extending from the input oil chamber (16) to the pressurized oil feed port (27), is provided with a nonreturn valve capable of discharging pressurized oil from the input oil chamber (16). The nonreturn valve (9) is opened when the pressurized oil is discharged through the pressurized oil feed port (27). The resulting hydraulic lock device is exceptionally dependable and reliable, operating at a high output with a small size and low-pressure hydraulic supply source.
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