Abstract: Fluid driven down-the-hole drilling machine. The hammer piston (2) of the down-the-hole drilling machine is adjacent to its front end provided with a cylindrical part (6). The drill bit (3) is provided with a first impact surface (41) which receives impacts during drilling, a second impact surface (42) and an annular section (7) which surrounds the cylindrical part (6) between the impact surfaces. The second impact surface (42) receives the impact energy of the hammer piston at reversed feeding of the housing (1) of the down-the-hole drilling machine for freeing the drill bit when it has become stuck.

Abstract: Rock drilling device for drilling with a drill string comprising a set of tubes (1) and a set of rods (2) arranged centrally in the set of tubes.

Abstract: Liquid driven hammer machine with a machine housing (1) and a hammer piston (2) moveable to-and-fro in guides (4,5) in the machine housing. The guides are made with an intermediate section (6) and end sections (7,8) on either sides thereof. The slot between the intermediate section and the hammer piston is less than, preferably one half of, the slot between the end section and the hammer piston at the end of the end section turned away from the intermediate section. The intermediate section has according to an advantageous embodiment an ax/al extension which is approximately one third of the length of the guide.

Abstract: Drill string component for use at drilling with a liquid driven down-the-hole drilling machine (1) comprising three coaxial tubes (2,4,6) for forming channels for supply of driving medium to the down-the-hole drilling machine, return of the driving medium after it has done its work and supply of flushing medium to the bore hole. The outer tube (2) of the drill string component is provided with a first end piece (7) which is axially displaceable relative to the outer tube and axially lockable relative to the outer tube in an outer position so that the inner tubes (4,6) are protected against damage when the drill string component is not connected with another drill string component, the hammer device (1) or a rotary device (9) for rotation of the drill string.

Abstract: Hammer device comprising a machine housing (1) with a hammer piston (2) movable to-and-fro. The movement to-and-fro of the hammer piston is controlled by a valve body (6) movable to-and-fro in the machine housing. In order to speed up the turning of the hammer piston at its rear end position the machine housing is provided with a room (10) which by the hammer piston is separated from connection with the valve body (6) at the same time as the rear end surface (5) is supplied with pressure fluid via a connection (11) opened by the hammer piston to the pressure source (8) when the hammer piston approaches its rear end position.

Abstract: Rock drilling device comprising a backhammer unit (10) in which a hammer piston (9) is movable to-and-fro for automatically exposing a tube string (4) to impacts in a direction away from a drill bit (8) in the tube string. The backhammer unit comprises a housing (13) and a springloaded tube part (14). The housing and the tube part form between them a first valve (16) and a second valve (17). At drilling the first valve which controls the supply of driving medium to said hammer piston is closed and the second valve which controls the flushing medium flow is open. At backwards feeding of the rock drilling machine (2) along the feed beam (1) with a force which exceeds a predetermined value the first valve is open and the second valve is closed.