| 摘要 |
The invention relates to a process and device for pulling a pipe (2) laid or to be laid in the ground towards an underground trench accessible from the ground level, in which there is a pulling device in engagement with a traction component (3). The traction component (3) extends through the pipe (2) and is engaged at its rear end, in relation to the direction of pulling, and together with the pipe (2) is then pulled towards the trench, in steps, by the pulling device provided with the traction mechanism which makes forward and backward strokes at each step. During the backward stroke the traction component is kept under a stress corresponding to its elastic expansion during the forward stroke. Thus, the traction component (3) is kept permanently under stress throughout the pulling process, thereby preventing the traction component from expanding and contracting at each step. In a preferred embodiment, the traction component (3) has catches (4) and the pulling device has a pulling yoke (12), which engages one of the catches (4) during the forward stroke, and a retaining yoke (17) which engages one of the catches (4) during the backwrd stroke.
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