Abstract: A rock drilling machine, e.g. for drilling with a diamond core bit, has a first power rotated chuck for gripping the drill string. The first chuck can be swung offset the drilling axis into a position to grip an input shaft of a reduction gearing coupled to a second chuck. The first chuck and its motor can thus rotate also the second chuck which is used for example for drilling down a borehole lining pipe. The two chucks are mounted on a common slide that is power feedable back and forth along a feed beam or mast.

Abstract: A drill string holder for a rock drilling machine has two jaws opposite each other for gripping a drill string, e.g. the drill string in core drilling with a diamond drill bit. The jaws are forced into their gripping positions by means of a heavy spring. A first selectively actuatable hydraulic piston is arranged to overcome the spring and permit the jaws to release their grip. A selectively actuatable second piston is located inside the first piston. By means of the second piston, the operator can apply a selectively variable force to the jaws when the jaws are released from the spring. This permits the operator to let the drill string gently down into the bore hole by applying a controlled braking force on it.