Abstract: The invention relates to a double diaphragm pump having flexible diaphragms disposed in displacement spaces and connected and mechanically coupled to piston rods, the displacement spaces being communicated via check valves to a suction manifold on the one hand and to a pressure manifold on the other hand, wherein each diaphragm is connected to a piston rod, which piston rods extend coaxially and are mounted on opposite sides to a guide frame having at least one lineal guide for a guide block which rotatably mounts a crank pin of a crankshaft.

Abstract: An apparatus for controlling the hydraulic circuit of a piston diaphragm pump, having at least a pump diaphragm alternatingly subjected to the presure or the suction stroke of a piston operatingly connected to driving means, the apparatus comprising control means changing the amount of hydraulic medium displaced by the piston in dependence of a power demand or the like. A displacement sensor is associated with one side of the diaphragm facing the hydraulic medium, the sensor measuring the stroke travel of the diaphragm and generating a corresponding stroke travel signal which is transmitted to control means, the control means including storage means storing predetermined stroke values and/or stroke value ranges for predetermined hydraulic power values of the pump.