Abstract: A catch mechanism for latching a shank of a head housing in a guide sleeve of a grip piece which latch mechanism includes stop surfaces engaged by catch surfaces characterized by an actuation element being carried on the grip part and movable radially inward to shift the catch surfaces from a first position engaged with the stop surfaces to a second position disengaged from the stop surfaces. In one embodiment, the catch surfaces are carried on a shank of the head part and the stop surfaces are on a guide sleeve of the gripping part. In other embodiments, the stop surfaces are provided on the shank of the head part and the catch surfaces are formed by an element carried on the guide sleeve.