| 摘要 |
A device in pressure medium operated needle hammers, the needles (24) being arranged in a reciprocatingly movable working member (3) by at least one flexible holder member (31, 39) and, by a friction grip of the holder member being caused to follow the movements of the working member, but being permitted an axial play within predetermined limits through overcoming the frictional resistance. In addition, the rear portions of the needles can be arranged in a sealed chamber (34) filled with a hydraulic medium (35). |
