Electro hydraulic door-drive - has overflow passage connecting ram working chamber to other side on shutting

摘要

The electro-hydraulic drive is for the leaf of a door, having a ram whose piston is coupled to the leaf and spring-loaded into the shut position. The working chamber of the piston is on the side of the latter to which it moves under spring action. It can be connected to the outlet side of an electrically-driven pump (3). The other side of the piston, to which it moves on opening the door, is connected to the hydraulic reservoir or the pump suction side. With the piston (2) in the shut or nearly-shut position, the working chamber (8) is connected by an overflow passage (42,42') to the other chamber (12'), the reservoir (6) or the suction side of the pump. When the door is opened by the pump a plug shuts the overflow passage off at least partly. ADVANTAGE - Ensures door is fully shut.