Power tightening device having detachable socket unit
 A power tightening device having a unit of inner socket with a bolt tip engaging bore and outer socket with a nut engaging bore which unit can be attached to and removed from the main body of the device. The inner socket is engageable with or disengageable from a planet gear support frame axially thereof and is rotatable therewith. The device includes a holder main body concentrically formed with a non-circular hole and rotatably fitted in the front end of an inner gear case, and a bearing plate disposed on the inner side of the holder main body rotatably with the gear case and concentrically formed with a non-circular hole identical with the hole in shape. The outer socket has a flange conforming to the shape of the holes of the holder main body and the bearing plate. The holder main body is provided with an engaging member for softly holding the holder main body to the bearing plate. 
Nissan Motor Co., Ltd. Maeda Metal Industries Ltd.
B
B25B
inventional
Yukio Masahiro
Uemura Fujita