Abstract: The piston membrane pump has a feed chamber for the fluid to be pumped and a piston working chamber, a membrane hermetically separating the feed chamber and the piston working chamber and a piston oscillating back and forth in the piston working chamber. The piston working chamber is completely filled with a hydraulic medium from a supply container in operation so that the membrane oscillates with the piston. A refill valve which connects the piston working chamber with the supply container cooperates with a spring-loaded sliding control element and a moving force-transmitting element displaceable against it so as to open the valve. So that the pump can operate at higher pressures and temperatures a metal membrane is used, the force-transmitting element is a resilient platelike piece acting against the spring-loaded sliding control element and the membrane has no contact surfaces in the feed chamber on its feed chamber side.

Abstract: A diaphragm plunger pump comprises a housing, element forming a pump chamber associated with the housing, a plunger working chamber arranged to be filled with hydraulic fluid during operation, a sealingly clamped diaphragm separating the pump chamber from the plunger working chamber, a plunger sealing displaceable in the plunger working chamber for alternating stoke plunger working chamber for alternating stroke deflection of the diaphragm, a supply chamber for hydraulic liquid and connectable with the plunger working chamber, a valve arranged to connect the supply chamber with the working chamber, the plunger having a central opening provided with a valve seat and serving for communication of the plunger working chamber with the supply chamber, the valve having a valve body which cooperates with the valve seat and is coaxially displaceable relative to the latter, element for sealingly pressing the valve body against the valve seat, and abutment element arranged to lift the valve body from the valve seat when

Abstract: A piston diaphragm pump includes a support plate, disposed on the side of the piston work chamber, for the diaphragm, which is held in a freely movable manner counter to the pressure of a plurality of springs engaging its circumference. A control push rod under the pressure of another spring, counter to the support plate, engage the circumferential area of the support plate and has a conical recess on its circumference, along which slides a displaceable locking member for a refill valve for the hydraulic fluid during the movement of the control push rod. The refill valve opens only when the support plate displaces the control push rod counter to the pressure of its spring as a consequence of a lack of hydraulic fluid in the pump.