| 摘要 |
A pneumatic unlocking and closing apparatus for doors has a soft braking phase at each end position. The apparatus includes a pneumatic piston-cylinder unit having a working chamber acting on a large piston area and a return chamber acting on a piston area which is reduced by the piston rod. The apparatus is operated by a substantially closed pressure actuation system having a compressed air pump creating both a working pressure in the working chamber and a less high counter pressure in the return chamber. The pressure system includes a first or plus tank having a certain predetermined high pressure to act as the working pressure in the working chamber for expelling the piston during the ordinary working stroke thereof; and a second or minus tank into which the air of the working chamber is evacuated when the piston is to be returned to its fully retracted position. |
