ABSTRACT A power tong includes a frame and a pipe-gripping mechanism associated with a throat at one end of the frame. Power is transmitted to the pipe-gripping mechanism from a power unit comprising a multiple speed motor through a drive train. The pipe-gripping mechanism cooperates with the throat to receive a pipe section to be rotated and includes a partial ring rotatably mounted within the frame and having an opening which may be aligned with the throat. The ring may be rotated in either direction by the power unit. Mounted on the tong is a die carrier which is rotatable relative to the ring. Link members are pivotally mounted on the die carrier and include dies positioned to grip the external surface of the pipe section. The link members are arranged to cooperate with specially designed cam surfaces on the ring so that, when the ring is rotated relative to the die carrier, the dies moved into engagement with the pipe section. After the movable dies have engaged the pipe section further relative movement between the ring and the die carrier is prevented and the pipe section is therefore rotated to make up or break apart the threaded joint of the pipe. The drive mechanism comprises a multiple speed motor capable of rotating the partial ring in either direction. The motor includes a gear shaft which drives a pinion gear. A pair of pinion idler gears are positioned on either side of the pinion gear and are rotated thereby. A pair of rotary idler gears are driven by the pinion idler gears, and the rotary idler gears each drive a rotary gear associated with the partial ring.
Download Full PDF Version (Non-Commercial Use)