Pneumatic setting mechanism for locking tank flap etc.

摘要

On supplying the working chamber (2a) of a setting member (3) with pressures less than a lower threshold value, which in turn is less by a predetermined amount than a reference pressure, the member assumes a first position. It assumes a second position when the pressures are above a threshold pressure greater than the reference pressure. The setting-pressure chamber positions a valve unit with first non-return valve (11) opening when the inlet pressure is below the first threshold pressure. A second non-return valve (16) connected in parallel with the first opens when inlet pressure is above the second threshold pressure. A piston (15) sliding in the valve unit working chamber (14) divides it into two parts. The first (14a) is connected to the side of the second non-return valve furthest from the pressure source, and to the working chamber (2a). The second (14b) is connected to the side of the first non-return valve furthest from the pressure source.