Abstract: Power wrench apparatus for holding a drill rod stationary as a rod joint is being broken that includes a first piston cylinder combination for pivotally moving a mounting bracket relative to a frame between wrench rod clamping and releasing positions, a second piston cylinder and an arm member pivotally mounted on the mounting bracket, and a slide handle and a jaw actuator pivoted to the slide member and second piston cylinder respectively to act through a jaw bracket and the slide member to relatively move the wrench first and second jaws from their rod release to their rod clamping position when the mounting bracket is in its wrench clamping position when the piston rod of the second piston cylinder is extended.