| 摘要 |
<p>The loading spaces (35, 36) provided on both sides of the piston (38) of the actuating cylinder (37) are, in the case of pneumatic actuation, alternately connected to a compressed-air source (11) via a respective solenoid valve (2, 3) assigned to them or to the atmosphere via a throttling nozzle (31, 32). The actuating cylinder for closing and opening the door (6) is effective in both directions. Furthermore, each loading space (35, 36) is connected to the atmosphere via a respective non-throttled connection, in which a piston-controlled shut-off valve (17, 18) is located. The piston (19, 20) of the shut-off valves can be loaded, counter to the force of a spring (25, 26), in the closing direction of the shut-off valve by the pressure of the other respective loading space (35, 36). When one loading space is loaded with pressure, the compressed air of the other loading space escapes in a throttled manner, whilst the non-throttled connection is opened via the shut-off valves (17, 18) and manual actuation of the doors is guaranteed, without obstruction, when the solenoid valves (2, 3) are simultaneously located in a position opening their outlet valves (15, 16). The door (6) can thus be actuated by hand in a unrestrained manner, but the door movement is damped in the case of pneumatic actuation. <IMAGE></p> |
