| 摘要 |
<p>1. Jack capable of distinct and subsequent active strokes by the action of a fluid under pressure introduced at one end (6) of the jack cylinder (1) so that it acts on a piston (4) sliding inside the said cylinder (1), the jack comprising two coaxial rods, one of which is an internal rod (2) in a mechanically actuating connection (21) with a first control member at one end of the jack and an external rod (3) carrying the piston (4) and in a mechanical acting connection (24) with a second control member at the other end of the jack, the internal rod (2) being connected to the external rod (3) through a locking device (8) in such a way as to effect a mechanical action of the first control member over a fraction of the stroke of the piston (4) until the joint movement of the rods (2, 3) ends in their mutual release whilst permitting the operation of the second control member by the external rod (3), characterised in that the external rod (3) has a smaller diameter than that of the piston (4), whilst permitting a double acting operation which ensures the return of the piston (4) by means of fluid under pressure introduced at the other end (16) of the cylinder (1) and in that a seal (32) is located between the internal rod (2) and an end of the jack outside the external rod (3).</p> |
