Abstract: An open-mouth power tong of the type used to make up and break out threaded connections between tubular members includes an improved mechanism for properly aligning the pipe when it is gripped by the tong so that the pipe may be rotated evenly about its axis.

Abstract: An open mouth power tong is described having a novel arrangement for preventing relative rotation between the tong cage plates and rotary gear in situations where the pipe is not gripped at the completion of the camming action and in situations where the tong parts must be aligned for placing the tong on a pipe or removing it from a pipe. The assembly includes a pair of arcuate grooves formed in the upper surface of the rotary gear--one for use in make up operations and the other for use in break out operations. A rigid pin member is provided for extending through one of a pair of apertures formed in the upper cage plate. When the camming action is complete, i.e., when the cam followers have reached the extremities of the cam surfaces, the rigid pin member engages the remote boundary of the respective arcuate groove so as to join the cage plates and rotary gear and cause them to rotate together. When it is desired to align the tong parts for pipe access, the pin engages the near boundary of the groove.

Abstract: In a power tong of the type used in making up and breaking out threaded connections between pipe sections, the bearing surface between the upper cage plate and the tong top body plate is provided with improved means for reducing friction and other undesirable forces when the cage plate is rotatably driven with respect to the body plate. In a particular embodiment, the upper cage plate is provided with an arcuate groove which opens toward the opposing top body plate. The groove includes guide rollers mounted on vertical shafts for engaging the inner and outer arcuate walls of the groove to guide the cage plate when it is rotated. The groove also includes weight relief rollers mounted on horizontal shafts for providing a gap between the upper cage plate and its opposing body plate to eliminate metal-to-metal friction therebetween.