Pressure-medium cylinder for actuating ventilation and smoke-outlet louvres

摘要

A pressure-medium cylinder (1) for actuating ventilation and smoke-outlet louvres, the piston rod (2) of which is constantly loaded in operation in the direction of arrow (A) by an external spring (not shown), is provided with a locking device which can be actuated or unlocked solely as a function of pressure. To this end, a locking pin (13) can be axially displaced via a piston (12), specifically against the action of two springs (14, 15) of different strength. When a high pressure is applied, the locking pin (13) is moved into the area of catch balls (8) which as a result bear against corresponding annular surfaces (18) of a catch ring (5). If the pressure is lifted, the locking pin (13) first of all stays in its catch position, since it is clamped in place by the catch balls (8). If a lower compressed-air pressure is applied, the cylinder piston (3) is now relieved so that the catch balls (8) no longer apply any clamping forces to the locking pin (13) and the latter can be returned into its initial position, as a result of which the cylinder piston (3) together with piston rod (2) are freely movable again. <IMAGE>