REDUCED WEIGHT POWER TONG FOR TURNING PIPE

摘要

A power tong body having a central opening comprises upper and lower cover plates and a rotary gear contained there between. The tong incorporates the centering guide, e.g. rollers, that extend between the rotary gear and respective tong covers. Such centering guides through the central openings in the tong body covers and provide contact surfaces carried that permit differential rotation of the rotary gear with respect to such covers. The rollers may roll on circular races formed by the inside edge face surfaces of the tong covers bordering the central opening. The support rollers may also extend beyond the upper and lower cover plates and engage with a guide surface or race formed on the respective cage plates of the tong, centrally locating such cage plates with respect to the rotary gear while allowing differential rotation of the cage plates with respect to the rotary gear.