Abstract: In a pivoting-jaw power tong having a rotary gear with substantially linear camming surfaces and pivoting jaw members with cam followers for engagement with the camming surfaces upon rotation of the rotary gear relative to the jaw members, each cam follower has at least one contact surface configured for sliding engagement with a primary camming surface. The provision of sliding contact surfaces reduces contact pressures between the cam followers and the camming surfaces, thus reducing wear. The cam followers may be formed integrally with the jaw members, but preferably will be rollers which can swivel relative to their respective jaw members to facilitate substantially uniform sliding contract between the cam follower contact surfaces and the camming surfaces of the rotary gear. In alternative embodiments, the camming surfaces may have a slight concave curvature, with the cam followers' contact surfaces being correspondingly convexly curved.

Abstract: In a pivoting-jaw power tong, each primary camming surface of the rotary gear has a substantially linear rather than curved configuration. Each primary camming surface forms an acute angle with a radial line extending from the rotary gear centerline to the point where the primary camming surface transitions to its associated neutral recess. Accordingly, the radial distance to a point on any of the primary camming surfaces reduces linearly with increased distance from the neutral recess. Rotation of the rotary gear in either direction away from the neutral position thus results in a linearly progressive reduction in the distance from the center of rotation to the points where the pivoting jaws' cam followers contact the camming surfaces, thus increasing the force exerted by the dies of the jaws upon a tubular disposed within the jaws.

Abstract: In a pivoting-jaw power tong, each primary camming surface of the rotary gear has a substantially linear rather than curved configuration. Each primary camming surface forms an acute angle with a radial line extending from the rotary gear centerline to the point where the primary camming surface transitions to its associated neutral recess. Accordingly, the radial distance to a point on any of the primary camming surfaces reduces linearly with increased distance from the neutral recess. Rotation of the rotary gear in either direction away from the neutral position thus results in a linearly progressive reduction in the distance from the center of rotation to the points where the pivoting jaws' cam followers contact the camming surfaces, thus increasing the force exerted by the dies of the jaws upon a tubular disposed within the jaws.