Vacuum control device for the displacement of an element between at least three positions

摘要

A vacuum control device comprises a casing in which are disposed at least two substantially parallel movable cups, the first cup being connected to the element to be displaced. Springs are interposed respectively between the two cups and between the second cup and a bottom end-wall of the casing. Two pipes or nipples connected to a vacuum source and to atmospheric pressure open into the casing respectively within the space located between the two cups and within the space located between the second cup and the casing end-wall.