Patent ID: 7152692

Claim:
A hydraulic hammer comprising: a frame, which is an elongated piece and comprises an upper end and a lower end; a percussion device having an elongated percussion piston that is reciprocatingly movable into a stroke direction and a return direction by means of hydraulic pressure, and a plural number of pressure spaces around the percussion piston; pressure fluid channels for leading hydraulic fluid to the percussion device and away from it; a space formed inside the frame for the percussion device; bearing members mounting the percussion piston to the frame at least at upper and lower parts of the percussion piston; a tool which the percussion piston is configured to strike in the stroke direction, the tool being configured to transmit the strokes to a material to be broken; a tool bushing with which the upper part of the tool is bearing-mounted to the frame such that the tool is movable in axial direction; at least one lower seal for sealing the lower part of the percussion piston, at least one sealing bushing arranged in an annular space between the percussion piston and the frame; the inner diameter of the sealing bushing is dimensioned larger than the outer diameter of the percussion piston at the sealing bushing, whereby there is a clearance between the inner diameter of the sealing bushing and the outer diameter of the percussion piston; on the inner circumference of the sealing bushing there is disposed the at least one lower seal for sealing the clearance; the sealing bushing is arranged in place through the tool side frame end, and the sealing bushing is locked in place to the frame.