Abstract: A power tong and back-up tong assembly is comprised of a power tong having a rotatable cam surface which cooperates with jaw assemblies to grip and rotate a first pipe and a back-up tong having a fixed cam ring and jaw assemblies which are rotated against the cam ring in the same direction as the cam surface of the power tong rotates until an initial grip is achieved on a second pipe which is to be held while the first pipe is threaded or unthreaded relative thereto.

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: 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.