초록 ▼

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 forme

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.

대표청구항 ▼

An arrangement for an axial bearing in a drilling machine comprising a frame (6); a percussion device (1) fitted in the frame; a shank (2) positioned on an axial extension of the percussion device and having a percussion surface adapted to be struck by said percussion device; means for rotating the

An arrangement for an axial bearing in a drilling machine comprising a frame (6); a percussion device (1) fitted in the frame; a shank (2) positioned on an axial extension of the percussion device and having a percussion surface adapted to be struck by said percussion device; means for rotating the shank (2); and an axial bearing fitted in the frame to receive axial forces acting on the frame (6) through the shank (2), the axial bearing being formed by a plurality of pistons (4a, 4b) accommodated in axial housings formed in the frame (6) along a periphery circumscribing the shank (2) and interconnected with a conduit system (7), the pistons being further arranged to travel an axial distance axially so as to act on the shank (2) to force the shank towards a forward portion of the drilling machine under the influence of a hydraulic fluid acting on respective back surfaces of the pistons; and means for limiting the axial travel distance of a first group of said plurality of pistons towards the forward portion of the drilling machine relative to the axial travel distance of a second group of said plurality of pistons so that when said plurality of pistons are in a foremost position and the shank (2) is supported by said plurality of pistons (4a4b), the percussion surface of the shank is positioned substantially at its optimal percussion point, whereby the pressure of the hydraulic fluid acting on the back surface of the pistons (4a, 4b) at least during the drilling is arranged to be such that the total force exerted on the shank (2) by said plurality of pistons so as to force it forwards exceeds the feed force acting on the drilling machine during drilling.