US Patent 7121166 Power tong assembly

A tong assembly comprises a body and a center member slidable relative to the body. A pair of clamping arms is rotatably connected to the body. The clamping arms are connected to the center member such that as the center member slides relative to said body, the clamping arms rotate relative to the body. The assembly also comprises a plurality of die assemblies, wherein at least one die assembly is mounted to each clamping arm and at least one die assembly is mounted to the center member.