IMPROVED CAM FOLLOWER FOR POWER TONGS AND OTHER USES

摘要

A power tong or back-up tong has a jaw assembly (6) that is advanced into engagement with a pipe (13) through a cam follower that contacts the camming (10) surface on the inside circumference of a ring gear (9), the cam followe r being in the form of a series of roller elements (14) arranged as a circulating bearing. In a preferred form, the roller elements are cylindrica l roller bearings and the jaw assembly is mounted for sliding advancement towards the pipe to be engaged. In an alternate variant the cam follower includes an indexing guide (30) that maintains the cylindrical roller bearin gs in proper alignment.