Detachable torque transmitting tool joint

Abstract

A device for transmitting torque from a power unit to a drill string or other rotary pipe, and which is constructed upon reverse rotation to preferentially break a threaded connection between the device and a stand of the pipe without disconnecting a plurality of lengths of pipe in the stand from one another. The torque transmitting device includes a tubular structure having a thread adapted to be advanced into engagement with a thread at an end of the pipe, and a shoulder ring carried by and rotatable with the tubular structure and having a shoulder engageable against a shoulder of the pipe to limit advancement of the threads together, with axial forces being transmitted from the tubular structure to the ring by interengageable bearing surfaces which permit limited rotary movement of the structure and its thread relative to the shoulder ring. The bearing surfaces are constructed to retain the ring in a predetermined fixed axial position relative to the tubular member, preventing axial movement of the ring relative to the structure as the structure turns about its axis relative to the ring. A C-spring disposed about the tubular structure acts to yieldingly urge the ring rotatively relative to the structure in a joint breaking direction. Two elements connected to flanges formed on the tubular structure and ring respectively are received between opposite ends of the C-spring and act to apply the force of the spring to the ring to urge it rotatively relative to the structure in the joint breaking direction. Pins received radially between the tubular structure and the ring limit their relative rotation to an angle constituting a small portion of a turn.