POWER TONG

摘要

A power tong (1) for rotating a tubular (40) in wellbore operations, the power tong comprising an outer case (2), a rotary (3) rotatably mounted in the outer case (2) for rotating a tubular (40), apparatus (4) for rotating the rotary (3) to rotate the tubular (40), at least one active jaw (8) movably mounted on the rotary (3) and displaceable relative thereto to grip the tubular (40), the at least one active jaw (8) having a gripping element (15) for contacting the surface of the tubular (417), and wherein one of said active jaw (8) and said rotary (3) is provided with a cam (27) and the other with a cam follower ( 19), characterized by pre-load apparatus (28, 29) interconnected directly or indirectly between the at least one active jaw (8) and the rotary (3) for, in use, displacing said active jaw (8) with respect to said rotary (3) so that the active jaw is cammed into gripping engagement with the tubular (40) and so inhibit relative rotation between said active jaw (8) and said tubular (40) on subsequent rotation of said rotary (3).