Abstract: A pressure fluid operated impact device comprising a frame (2) whereto a tool (3) is mountable movably in its longitudinal direction, and control means (7) for controlling pressure fluid feed to the impact device (1), as well as a method of generating a stress pulse in a pressure fluid operated impact device. The impact device (1) comprises a working chamber (8) and a transmission piston (9) moving therein. Energy charging means for charging energy of pressure fluid and the control means are coupled to allow periodically alternately pressure fluid to flow to the working chamber (8) and, correspondingly, to discharge pressure fluid from the working chamber (8). In the method, pressure fluid is fed to the working chamber (8), which produces a force pushing the transmission piston (9) in the direction of the tool (3), thus generating a stress pulse in the tool (3).

Abstract: A rock drill includes a housing in which are disposed a reciprocable percussive device, slidably mounted in the housing, a rotary device, and a shank adapter aligned with the percussive device. The shank adapter includes first and second adapter portions. The first adapter portion has a front end and a rear end, the rear end arranged to be impacted by the percussive device and rotated by the rotary device. The second adapter portion has a rear end releasably connected to the front end of the first adapter portion, and a front end carrying a coupling adapted for connection with a drill rod component.

Abstract: A method for adjusting percussion pressure and a drilling machine. In the method the percussion power of a drilling machine is adjusted by moving a shank in the longitudinal direction of the drilling machine forwards when a smaller percussion power is to be transferred from the percussion piston to the shank. The drilling machine comprises at least two groups of pistons moving in the axial direction of the drilling machine, the pistons being connected to act on the shank by means of a pressure medium acting behind the pistons towards the front end of the drilling machine. The drilling machine comprises at least two separate groups of pistons whose travel with respect to one another is different and where pressure medium channels separate from one another lead to the cylinder spaces of both piston groups.

Abstract: A hydraulic control system for use with a rock drill is adapted to sense a pressure build-up in the drill's rotation motor and in response thereto, to reverse the direction of feed of the feed motor as well as to supply hydraulic fluid to a shank cylinder on the rock drill. Supplying hydraulic fluid to the shank cylinder assists in freeing the drill from the rock.

Abstract: A hydraulic drilling apparatus, especially a rock drill comprising a body, a cylinder in the body and a percussion piston reciprocating in the cylinder. A tool is connected to the body and a motor is provided for rotating the tool. A control valve is also provided for the percussion power. A control valve is also provided for regulating the motor speed. Both of these control valves are operated independently by one lever. A hydraulically operated flushing valve is also provided. A hydraulic pump and hydraulic channels coact to form a percussion circuit and a rotation circuit is parallelly coupled with the percussion circuit in relation to the hydraulic pump. A flushing valve circuit is controlled by the percussion circuit and a circuit for the free circulation of the hydraulic pump which is parallelly coupled with the percussion circuit in relation to the hydraulic pump. The circuits are connected to the hydraulic pump.