Abstract: For clampingly holding a drill rod or the like, clamp apparatus that includes a mounting frame having spaced side members, a jaws holder having upwardly diverging end walls and bounding an opening for clamp jaws, longitudinally spaced jaw actuators that include piston cylinder combination having cylinders pivotally mounted on the jaw holder, and piston rods for moving jaw brackets upwardly and outwardly of one another, each bracket having an inclined leg extending into the jaw opening in slidable relationship with the adjacent end wall and into slots in the holder side walls, and side walls that have interleaving portions that maintain the brackets at substantially the same elevation relative one another while permitting the brackets moving longitudinally toward and away from one another, and a pin for releasably mounting each jaw to the respective bracket in abutting relationship to the adjacent bracket leg to move therewith, the jaws having semi-circular rod receiving recesses, the holder having oppositely