| 摘要 |
<p>A sleeve (1-6) in which is engaged and held at least one elastic means (2-7) which may or may not extend via one of its ends, a rigid, intermediate casing (3-8) being fitted partially over the length of each elastic means, at least one pin (4-9), which is free to move in translation, passing angularly through at least the said casing in order to permit, under the effect of a pushing force, the rotation and the twisting of the elastic means on itself, inside the sleeve. <IMAGE></p> |
