| 摘要 |
PCT No. PCT/FI91/00049 Sec. 371 Date Aug. 14, 1992 Sec. 102(e) Date Aug. 14, 1992 PCT Filed Feb. 18, 1991 PCT Pub. No. WO91/12934 PCT Pub. Date Sep. 5, 1991.The invention relates to an arrangement for an axial bearing in a drilling machine. The drilling machine includes a frame (6), a percussion device (1) fitted in the frame, and a shank (2) positioned on an axial extension of the percussion device. The frame (6) further includes an axial bearing formed by a number of pistons (4a, 4b) to receive axial forces acting on the frame (6) through the shank (2). The length of travel of some pistons (4b) towards the forward portion of the drilling machine is limited so that when they are in their forward position and the shank (2) is supported by the pistons (4a, 4b), the shank (2) is substantially at its optimal percussion point.
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