Making and breaking of couplings between pipe sections in a drilling rig

Abstract From the Canadian patent

For making or breaking a coupling between a pipe section (1) and a pipe string (2) projecting from a rotary drilling rig into a bore hole in the lithosphere the pipe section (1) is rotated relative to the pipe string (2) by applying a torque up to a make-up or breaking torque. Exertion of said torque generates a reactive torque in an opposite sense of rotation. Rotation induced by a motor (17; 50) is transferred to the pipe string (2) so that said pipe string (2) is rotated as well. The reactive torque is transferred to the pipe string (2) along a path bypassing the motor (17; 50). Thus the make-up or breaking , torque can be exerted without requiring a substantial change of the …