Abstract: A device for the fastening of hammers in axially extending cutouts of rebound-mill rotors having a form-locked attachment between each hammer and one side of the corresponding cutout and a force-locked attachment on the other side by means of at least one wedge-shaped clamping ledge which can be acted on in clamping direction by a plurality of pressure elements each of which has a clamping piston acted on by a pressure medium and which are connected to each other by a common pressure conduit which can be closed by a valve. The clamping pistons are arranged in the clamping ledge and are connected by the pressure conduit which debouches in at least one end surface of the clamping ledge and is filled with a flowable, plastic, compressible pressure medium which, in order to obtain excess pressure, can be acted on by a setting piston which is developed on a closure screw which can be screwed into the mouth of the pressure conduit.