Camming system for power tong jaws

摘要

A power tong or back-up tong has a jaw assembly that is advanced into engagement with a pipe through a cam follower that contacts the camming surface on the inside circumference of a ring gear, the cam follower being in the form of a series of roller elements arranged as a circulating bearing. In a preferred form, the roller elements are cylindrical roller bearings and the jaw assembly is mounted for sliding advancement towards the pipe to be engaged.