| 摘要 |
<p>The invention relates to a step-by-step jack with safety device, in which a traction support such as a cable (A) is actuated by a set of clamps which is mobile relative to a set of clamps fixed at a reference position, one of the two sets of clamps being clamped against the traction support and the other unclamped while the two sets are being moved apart, and conversely while they are being moved together. The jack is characterised in that at least one set of clamps is provided with a safety device possessing a detection member (12) for detecting any movement of the traction support at the level of this set while the latter should be clamped, and a closure trigger member (15) for clamping the other set of clamps in this situation. The invention may be used in construction techniques. <IMAGE></p> |
