Electrohydraulic actuator for brakes for industrial plant

摘要

The actuator has a pump-motor unit and piston-cylinder unit with a sealed piston rod passing through the piston-cylinder unit housing and a spiral brake spring (34) enclosing the rod in the housing. At least the housing part enclosing the spring is filled with hydraulic oil which is not under pressure. The actuator is of block construction for high pressure with a thickened base region contg. the spring which is guided in an aperture sealed against high pressure. The high pressure side in the aperture and the low pressure side in the spring are connected via channels (40,41) opening into a hydraulic system return container (47). A blocking element between the high and low pressure sides forms a shaft valve (53,53') and there is at least one overpressure valve (52,52') between the high and low pressure sides.