Safety coupling for rotary pump

Abstract From the Canadian patent

A safety coupling for preventing backspin at excessive speeds of a torque transmitting drive powering a drive string which stores reactive torque due to torsional stress. The safety coupling includes a rotatable driving member to be coupled with a torque producing power source a rotatable driven member to be coupled with the drive string for axial rotation therewith. The driven member is movable relative to the driving member between an engaged position wherein the driving and driven members are coupled by a torque transfer structure to provide a positive driving connection between the torque transmitting drive and the shaft and a disengaged position wherein the driving and driven members …