CH622980

A hammer drill has a chuck forming a tool receptacle defining a chuck axis and provided with a tool-holding element radially displaceable into a position protruding into the tool receptacle. The tool has a shank defining a tool axis receivable axially in the receptacle. This shank is formed with a radially outwardly open recess closed at both of its axial ends and shaped to receive the tool-holding element, and with an axially extending groove separate from the recess and open axially at a free end of the shank. At least a section of the shank has a conical shape decreasing in a direction towards the free end of the shank. The shank may be provided with at least one cylindrical guiding section located adjacent to the above conical section.