TIGHTENING BOLT

摘要

A tightening bolt capable of switching between the tightened state and the released state rapidly and easily, wherein a flange is tightened between the bolt head of the tightening bolt and a nut screwed onto a thread part through a spherical washer, a hollow part is formed inside the shaft of the tightening bolt, the shaft is extended so as to release the bolt when hydraulic oil is fed from the oil filler port of a plug member so as to increase a pressure inside the hollow part, whereby the tightening state of the nut to the tightening bolt is freed and, the nut can be removed easily manually even the tightening bolt is of a large type and, when the length of a clearance is adjusted and a hydraulic pressure applied to the hollow part is released, the tightened state can be obtained and a tightening force can be adjusted according to the clearance.