| 摘要 |
This device comprises, on the one hand, a carrying structure of known type, consisting of two arms, inner 4 and outer 5, hinged together, and cleaning means and hydraulic jacks 10-13 on the structure 2 and the chassis 16 respectively, which are interposed between the structure 2 and the inner arm 4 and between the two arms 4-5 respectively, but in which each of the actuating jacks 10-13 is of the single-acting type and is mounted so as to act in the extended position and, on the other hand, cleaning means A, the chassis 16 of which, hinged at the end of the outer arm 5 of the carrying structure 2, is joined to this arm 5 by a single-acting hydraulic jack 28 working in the extended position and carries a hydraulic motor for driving a mill 32 and on the opposite side to a smoothing tool 37 connected to this mill a guiding shoe 40. <IMAGE>
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