Abstract: A jaw assembly for a power tong or back-up tong is provided with a jaw die plate and a die seating surface that are shaped to permit radial insertion of the die plate (7) onto its seating surface (2). Both vertical (4) and horizontally (6) aligned splines, or spline segments are present on the seating surface. The vertical splines are interrupted along on at the end of their lengths by gaps (5a). Grooves (11) along with the protrusions (10) on the mating surface of the die plate interfit between the splines and/or spline segments and gaps to stabilize, or anchor the die plate on the seating surface against vertical displacement and to absorb rotational torque forces. The portion of the protrusions on the die plate that are positioned to extend into the gaps in the vertical splines support the die plate against vertical shearing forces, resisting disengagement of the die plate from its seating surface.

Abstract: A power tong (1) or back-up tong has a sliding jaw assembly (6) that may be advanced into the throat (4) of the tong for engagement with a pipe. A camming surface (11) on the inside circumference of the ring gear (10) advances the sliding jaw assembly into full engagement with the well pipe when the ring gear (10) is rotated with respect to the jaw assembly.