Abstract: A hand held hammer machine comprises a housing (10) with a cylinder (11) therein, in which a reciprocating drive piston (40) via a gas cushion in a working chamber (44) repeatedly drives a hammer piston (15) to impact on the neck (17) of a tool (20) carried by the machine housing (10) as soon as a feeding force is applied via the machine housing (10) to the tool (20) and an interposed recoil spring (23) pre-stressed between fixed shoulders (28,22) in the housing (10) starts being compressed in response to tool penetration into the housing (10). Therein and within the spring (23) and around the path of movement of a piston rod (13) of the hammer piston (15) is affixed one end (26) of a sleeve (25), which by its other end forms a stop (30) limiting the penetration of the tool neck (17) into the machine housing (10) to a maximally allowable extent.

Abstract: A portable hammer machine comprises a cylinder (11) in which a reciprocating drive piston (40) via a gas cushion in a working chamber (44) repeatedly drives a hammer piston (15) to impact on and to return from a tool (20) carried by the machine as soon as a feeding force is applied via the machine housing (10) to the tool (20) under compression of a spring (23) interposed therebetween. The cylinder (11) is on the one hand provided with primary ports (45) for the passage of gas to and from the working chamber (44), which ports (45) at impacting are opened above the hammer piston (15) to ventilate the working chamber (44), and on the other hand with secondary ports (46) for ventilating the volume (47) below the hammer piston (15) during its reciprocation and impacting. The spring (23) is pre-compressed in the machine housing (10) so as to balance the weight of the hammer machine when the latter is kept standing on the tool (20) with the hammer piston (15) resting against the tool (20).