| 摘要 |
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 forme d integrally with the jaw members, but preferably will be rollers which can swivel relati ve to their respective jaw members to facilitate substantially uniform sliding contact 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.
|
