Stellvorrichtung zur Durchführung von zwei Hubstufen

摘要

The activator comprises a housing (21) with an internal movable partition (22,23) fixed to the housing. The partition defines first (31) and second (32) pressure chambers. A movable element (24) connected to the partition moves with it towards the first chamber consequent to a differential pressure between the chambers. An intermediate stop (42) in the housing defines a third pressure chamber (51) in the first chamber and is moved toward this chamber as a result of a pressure difference between the first and third chambers. A first movement stage corresponds to the movement of the movable element and the intermediate stop when a negative pressure is introduced in the first pressure chamber. A second movement stage corresponds to the movement of the movable element and the stop when a negative pressure is introduced in the third pressure chamber.