HYDRAULICALLY OPERATED CONTROL VALVE FOR MINE PROP

摘要

A valve device takes the form of a multi-part cartridge with a hollow stepped housing containing a stepped rod. A control piston at one end of the rod is opposed by the force of a main spring in a main chamber remote from the control piston. A valve closure member is axially displaceable relative to the rod. The valve closure member is normally held against a valve seating but pressure on the control piston displaces the rod and causes the valve closure member to be lifted from its seating via stop faces. An auxiliary chamber in the housing leads via a connection to some consumer appliance and forms, the downstream side of the valve. A compensating piston on the rod member opposes a face of the valve closure member open to the auxiliary chamber. A further spring in the auxiliary chamber holds the valve closure member on its seating. The valve can open independently of the control piston should the pressure on the upstream side of the valve exceed the consumer pressure. This upstream side usually leads to either the pressure line or a return line as determined for example, by a change-over valve. The valve closure member will respond reliably to increased pressure on the control piston which only has to overcome predetermined spring force independent of hydraulic pressure in the auxiliary chamber.