Abstract: The ON behavior of a pressure switch or a valve (134) differs from its reset behavior by virtue of the fact that the movable pressurized part (126) is connected to one of the parts of a magnet assembly (112, 114) which are movable in relation to one another.

Abstract: In a servo-valve, a metal bellows (70) is fitted onto an end section (66) of valve stem (26,42) lying at a distance from the seal (22), one end of said metal bellows (70) being supported rigidly in housing (72), while its other end engages the end of the stem. The metal bellows (70) are located in a pressure chamber (62) which is connected by a condensate coil (74) to the valve intake (12), whereby the cross-sectional area of the metal bellows (70) is made to match the area of the passageway of the valve seat (16). In this way, it is possible to achieve an overall compensation of the forces at the seal (22) or a desired additional load in the closed or open direction.