Patent ID: 6330911
Filing Date: 2001-12-18
Classification: E21B

Abstract:
A tong for rotating tubulars, the tong comprisinga tong outer case,a rotary movably mounted in the case for rotating a tubular,apparatus for rotating the rotary to rotate the tubular,at least one gripper movably mounted within the rotary and movable by the rotary to grip the tubular, the at least one gripper having at least one cam following member,at least one non-circular cam surface on the rotary, the at least one cam following member contacting and movable on the at least one non-circular cam surface for maintaining a desired position of the at least one gripper with respect to the tubular,at least one centering gripper on the rotary for facilitating the gripping of the tubular,the at least one non-circular cam surface having a shape of part of a spiral, wherein the spiral is an Archimedes spiral.