Hammer device

A hammer mechanism for use with a tool having channel therein, the hammer mechanism having a normal working mode of operation and a continuous flushing mode of operation, comprising:

• a machine housing (1) having a working chamber (4) therein;
• a driving piston (2) which is reciprocably movable in the machine housing (1);
• means coupled to said driving piston for reciprocably moving said driving piston (2) in the machine housing (1) to create a pressure-gas cushion in the working chamber (4);
• a hammer piston (3) in the housing (1) and which is arranged to be driven towards a tool (5) by the driving piston (2) via said pressure-gas cushion in the working chamber (4) and being selectively movable to a resting position at an extreme end position in the housing to define said continuous flushing mode, said extreme resting position being outside the normal range of operation of the driving piston (2) when the hammer mechanism is operating in said working mode;
• means (14) for transferring pressure-gas from the working chamber (4) to a channel (15) in the tool (5);
• the hammer piston (3) including cut-off means cooperating with the pressure-gas transferring means (14) for selectively turning on and cutting off the pressure-gas transference during the normal working mode of operation of the hammer mechanism, the hammer piston (3) cutting off the pressure-gas transference to the tool channel (15) during a major portion of the working stroke of the hammer piston;
• means including a damping chamber (6) cooperating with and stopping the hammer piston (3) in said extreme resting position during the continuous flushing mode of operation;
• and
• means including said hammer piston cut-off means for rendering the pressure-gas transferring means (14) in continuous communication with the tool channel (15) and the working chamber (4) when the hammer piston (3) is in said extreme resting position so that the pressure created in the working chamber (4) by the driving piston (2) generates a flushing flow of pressure gas to thereby provide said continuous flushing of the tool channel (15).