Power tongs

DETAILED DESCRIPTION A power tong is provided in accordance with the present invention which includes a frame having a pipe-gripping mechanism associated with a throat defined at one end of the frame.
Power is transmitted to the pipe-gripping mechanism from a power unit through a drive train.
The pipe-gripping mechanism cooperates with the throat to receive a pipe section to be rotated.
The pipe-gripping mechanism includes a partial ring rotatably mounted within the frame and having an opening which may be aligned with the throat so that the pipe section may be positioned within the ring.
This ring may be rotated in either the clockwise or counterclockwise direction by the power unit and drive train which cooperates with gear teeth rigidly fixed to the ring.
A die carrier is mounted on the tong and is rotatable relative to the ring.
The die carrier includes die members which are mounted on the carrier and have dies positioned to grip the external surface of the pipe section which is to be rotated.
The die members are arranged to cooperate with cam surfaces on the ring so that, when the ring is rotated relative to the die carrier, the dies are moved rectilinearly 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 a threaded joint of pipe.