Automatic door closing actuator with free-run facility - has hydraulic lines which interconnect hydraulic chambers in actuator and can be connect to non-pressurised area

摘要

The arrangement consists of a cylinder which is filled with hydraulic fluid and which is divided into two areas by a piston (4). The piston is connected to the rod which carries out the door closing operation. A spring (8), which exerts the closing force, acts at one end against the piston and at the other end against a second piston (9) which forms an axially movable wall of a pressurised area (14). The pressurised area is connected to a second pressurised area (13), which is formed between the cylinder cover (3) and the piston, by a line (15). A second line (30), for the hydraulic fluid, connects to the first line and opens, via a valve (31), to an area which is not pressurised.