| 摘要 |
A door closing device comprises a piston (19) having at one end a seal (21) which seals the interface between the piston and a housing. The seal seals an aperture (29) in the piston and is displaceable by fluid pressure. A tubular portion (33) of the seal engages a fixed flow control element (32) provided with a recess (34) adjustably positioned relative to a port (41). A pressure relief valve is provided on the piston and has a valve element urged by a spring 38 transverse to the path of movement of the piston. <IMAGE> |
