| 摘要 |
What is proposed is a door-actuating device which is provided with a door valve (9) for a compressed-air-actuated to-and-fro movement of a door (1) and with an emergency valve (17), by means of which the two working chambers (5, 6) of the working cylinder (4) moving the door (1) can be made pressureless, in order to move the door (1) by hand. The emergency valve (17) has three locks (20/21; 33/34; 43/34), of which one (20/21) is releasable mechanically and the other two (33/34; 43/34) pneumatically or electromagnetically. This ensures that, although a change-over from power operation to manual operation can be brought about in any operating position of the door (1), nevertheless, conversely, a change-over from manual operation to power operation is possible only when first the mechanical lock (20/21) is released and then the lock (33/34; 43/34) is cancelled pneumatically or electromagnetically by the driver as a result of actuations of the door valve (9). The non-mechanical third lock (43/34) is formed by a pre-catch (43) which prevents the door (1) from being moved when the emergency valve (17) is not fully switched through. <IMAGE> |
