Power-driven hammer

Power-driven hammer with a pneumatic percussion mechanism having a retention device with holding elements (5, 30, 30', 50, 60, 80, 100, 110, or 120) which retain the striker (3, 3', 3'', 3''', 3''') during idling. The holding elements (5, 30, 30', 50, 60, 80, 100, 110, or 120) are controlled by the striking pin (4, 4', 4'', 4''', 4'''), the tool shank, a shifting sleeve (69) or another movable component of the percussion mechanism, so that, when the hammer is lifted off from the masonry, they engage with their hook-like extensions (6, 31, 51, 61 or 81) or a groove (7, 7', 7'', 7''') of the striker (3, 3', 3'', 3''', 3''') and retain the latter. When the hammer drill is restarted, they are automatically disengaged, so that the percussion mechanism is reactivated. By means of the retention device, the idling travel of the striker is reduced considerably; furthermore, it is possible to do away completely with the otherwise customary idling bore provided in the guide tube for the piston. The holding elements may be prestressed outwardly by an inner spring ring 10 and biased radially towards the striker 3 by a spring ring 9. The elements may assume the form of an annular spring, biased rocking levers, elastic blocking sleeve or a sprung rigid sleeve 120.