Hydraulic lock device

A hydraulic lock device, comprising a rod as an output member, a sleeve with a thin-walled portion fittable over the rod and elastically deformable to a smaller diameter, a casing member for supporting the sleeve, and an external hydraulic chamber formed around the sleeve, wherein said hydraulic lock device is characterized in that a rod-moving hydraulic cylinder is provided for moving the rod in the direction of the axial center, and the interior of the casing member is provided with an annular pressure booster for pressurizing the oil in the external hydraulic chamber;

• the casing member is provided with a pressurized oil feed port for feeding pressurized oil to the rod-moving hydraulic cylinder and the input oil chamber of the pressure booster;
• the oil channel extending from the pressurized oil feed port to the input oil chamber is provided with a sequence valve that is opened against the elastic force of a valve-closing spring after the oil pressure in the pressurized oil feed port has risen to a prescribed level;
• and
• an oil discharge channel extending from the input oil chamber to the pressurized oil feed port is provided with a nonreturn valve capable of discharging pressurized oil from the input oil chamber, with the nonreturn valve being opened when the pressurized oil is discharged through the pressurized oil feed port.