Abstract: A hydraulically driven diaphragm pump with a diaphragm clamped at its edge between a pump body and a pump cover separating a delivery chamber from a hydraulic chamber and pretensioned in the direction of its intake stroke by spring force. A hydraulic diaphragm drive in the form of an oscillating displacement piston is displaceable in the pump body between a reservoir chamber for the hydraulic fluid and the hydraulic chamber. The diaphragm is so strongly pretensioned by spring force that it exerts a substantial compressive force on the hydraulic fluid in the hydraulic chamber. Therefore a substantial hydrostatic pressure is built up in the hydraulic chamber relative to the delivery chamber.

Abstract: In a hydraulically driven diaphragm pump with a diaphragm clamped at its edge between a pump body (2) and a pump cover (3), separating a delivery chamber (4) from a hydraulic chamber (5) and pretensioned in the direction of its suction stroke by spring force, and with a hydraulic diaphragm drive in the form of an oscillating displacement piston (6) which is displaceable in the pump body (2) between a reservoir chamber (8) for the hydraulic fluid and the hydraulic chamber (5), characterised in that the diaphragm (1) is so strongly pretensioned by means of spring force that it exerts a substantial compressive force on the hydraulic fluid in the hydraulic chamber (5) and that therefore a substantial overpressure is built up in the hydraulic chamber (5) against the delivery chamber (4).