Patent ID: 8087650

Claim:
A clamping device for fixing a clamping object to a base by releasably engaging with an inner wall of a hole or a side wall formed in the clamping object, the clamping device comprising: a clamping main body fixed to the base and which is communicatingly formed with a rod insertion hole and a piston receiving cavity; a clamping rod which is inserted through the rod insertion hole of the clamping main body, a top-end portion of the clamping rod protruding from the clamping main body, the top-end portion being provided with an engagement portion engageable with the inner wall of the hole or the side wall; a piston member movably mounted in the piston receiving cavity of the clamping main body; a rod support mechanism which includes a pivot about which said clamping rod is movable and which moves the engagement portion of the clamping rod in a direction roughly rectangular to the longitudinal direction of the clamping rod and switchably supports the clamping rod in the clamping main body or the piston member between a clamping position of the clamping rod and a clamp release position of the clamping rod; a piston driving mechanism for driving the piston member between a first position corresponding to the clamping position of the clamping rod and a second position corresponding to the clamp release position of the clamping rod, the piston driving mechanism being provided with a spring which urges the piston member to the first position corresponding to the clamping position of the clamping rod and with a hydraulic chamber for driving the piston member to the second position corresponding to the clamp release position of the clamping rod by hydraulic pressure; and a cam mechanism for driving the engagement portion of the clamping rod in a clamping direction roughly rectangular to the longitudinal direction of the clamping rod by a driving force of the piston driving mechanism driving the piston member to the first position.