Abstract: A bolt tightening device having an inner socket and an outer socket arranged coaxially with each other and coupled to a motor by planetary gear mechanisms for tightening a reaction-bearing bolt with a nut thereon by engaging the nut in the outer socket and a tip at one end of the bolt in the inner socket. The inner and outer sockets are coupled respectively to two output shafts of the gear mechanism in the terminal stage which are rotatable in directions opposite to each other. The terminal gear mechanism has an axis displaced from the axes of the other gear mechanisms in parallel thereto, and has two input shafts coupled to two output shafts of the other gear mechanisms by way of first and second idle gears, respectively. This construction reduces the axial thickness of the socket side of the device, rendering the device easy to use.

Abstract: A device comprises a housing having a planetary gear reduction mechanism accommodated therein and a handle projecting therefrom, an electric motor or like rotation source attached to the housing for inputting power to the reduction mechanism, an outer socket coupled to an internal gear of the reduction mechanism and engageable with a nut, an inner socket coupled to a planetary gear support frame of the reduction mechanism and engageable with a bolt tip, and a torque detecting control mechanism for detecting a nut tightening force to discontinue supply of power to the rotation source upon the tightening force reaching a predetermined value. A friction ring is provided between the housing and the support frame coupled to the inner socket to effect frictional engagement therebetween. A definite axial tension is available by rotating the outer socket, i.e., the nut, with the inner socket in a fixed state.

Abstract: A device for tightening up nuts on torque-controlled bolts comprising an inner socket first output gear rotatably disposed within a housing, an outer socket second output gear rotatably disposed coaxially with the first output gear, an inner socket first input gear rotatably disposed on an axis parallel to the axis of the first and second output gears and meshing with the first output gear, and an outer socket second input gear rotatably disposed coaxially with the first input gear and meshing with the second output gear. The first and second output gears respectively have shafts projecting therefrom in the form of concentric circles to provide socket fitting portions at outer ends of the respective shafts. The first and second input gears respectively have shafts projecting therefrom in the form of concentric cir cles to provide coupling portions at outer ends of the respective shafts for connection to output shafts of a power tightening device.

Abstract: A clamping tool for use with a stud bolt includes a tubular body formed on its inner periphery with first female threads adapted to engage a stud bolt and second female threads. A drive shaft is provided on its bottom end with a threaded shank adapted to engage the second female threads. A torque transmission mechanism is provided between the tubular body and the drive shaft so that they will come into engagement with each other when the drive shaft is turned in a direction to tighten the stud bolt and get out of engagement when the drive shaft is turned in the opposite direction. Thus the torque necessary to loosen the clamping tool to detach it from the stud bolt tightened in position is much smaller than the torque necessary to tighten the stud bolt.