Torque responsive shutoff mechanism for power tool

Abstract From the Canadian patent

A fluid power tool having a torque responsive energy absorbing, nondisengaging drive mechanism interconnecting a motor and a driven spindle. The mechanism includes a driven member coupled to the spindle and a driving member connected to the tool motor and yieldably biased toward the driven member. The driven member has a plurality of spiral ball grooves disposed on the circumference thereof. The driving member has cooperable axial recesses. Bearing balls disposed in the recesses and grooves form a driving connection between the two members. The ball grooves are spirally sloped such that a preselected torque between the two members results in the rotation and axial translation of the driving …