| 摘要 |
PCT No. PCT/FI96/00299 Sec. 371 Date Nov. 28, 1997 Sec. 102(e) Date Nov. 28, 1997 PCT Filed Mar. 27, 1996 PCT Pub. No. WO96/38673 PCT Pub. Date Dec. 5, 1996The object of the invention is a method in a pneumatic oscillating device for observing an obstacle within the length of the work stroke and continuing the oscillating movement after this. The oscillating device includes a double-acting operating cylinder (1), a principal operating valve (6) controlling this, and a reversing valve (4), by which the principal operating valve (6) is controlled. A resistance to the flow on whichever return line (1.31, 1.41) of the operating cylinder (1) is in use, is arranged in order to maintain the return side pressure of the operating cylinder (1) at a level that is clearly higher than the ambient pressure during a work stroke in a normal situation, and sensing the pressure of the return side and, if it drops below a set limit, which is indicated by the movement of the pressure slowing or stopping completely, giving a command to the reversing valve (4) to change direction on the basis of this.
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