Pneumatic Jack

Pneumatic jack comprising a rigid jack body secured to an external edge of a deformable membrane so as to limit with said membrane a chamber of variable volume adapted to be subjected either to atmospheric pressure or to negative pressure, by means of an air inlet provided in said chamber, the body and the membrane each having an opening substantially centrally disposed, and a disk for at least partially closing each opening, each disk having a contour identical to but of a size slightly greater than the opening, said membrane having the general shape of a basin forming a bottom which is provided with a substantially central opening closed at least partially by the disk secured to the periphery of the opening, said disk coacting with the membrane so as to come into abutment against the bottom of the basin when the chamber is subjected to negative pressure, and a jack shaft sealingly secured in an opening of the disk secured to the membrane for directly transmitting the movement of the membrane to a member to be actuated.