Bolt or nut tightening device having reaction force receiving member

摘要

A bolt or nut tightening device comprising a tightening socket (4) and a reaction force receiving member (5), the tightening socket (4) being rotatingly drivable upon a speed reduction by a motor (2) and a reduction mechanism (3) which are incorporated in the device, the motor (2) being coupled to a controller (7) , the controller (7) being operable to deenergize the motor (2) in response to a tightening completion signal of detecting means (70) for detecting the completion of tightening of a bolt or nut and to reversely rotate the motor (2) only for a moment upon lapse of a predetermined period of time taken for inertial rotation of the motor (2) to reduce to an extent neglectable for the reverse rotation of the motor (2) after the deenergization, whereby the propping action of the reaction force receiving member (5) is nullified.