| 摘要 |
The subject of the invention relates to the technical field of means for controlling the opening and closing of movable frameworks. The shaft of the jack 1 comprises, in combination, two internal chambers 1a and 1b separated in a sealed manner, in each of the chambers there being mounted, in opposition and with free sliding, a piston rod 3a, 7a, in one of the chambers 1a the piston 3 is subjected to a thrust force under the effect of a fluid compressed at rest which tends to cause the rod 3a to emerge, whereas in the other chamber 1b, the piston 7 is subjected to an opposite force of predetermined strength, which tends to hold the rod 7a inside, one of the rods being connected to a fixed part of the dome, the other rod being connected to the opening part. <IMAGE>
|
