Abstract: A hydraulically driven diaphragm pumping machine comprises a plunger (6) that is slidably mounted in a middle part of the inside of the machine's hydraulic cylinder (5) between first and second bellow-like diaphragms (4,10). Ends of the plunger (6) are connected to the first and second bellows-like diaphragm (10) to define respective first and second outer annular spaces (a) that are independent of one another, and the pressure of fluid in the first annular space (a) is independent of the pressure of fluid in the second annular space (a). The machine may also comprise a hydromechanical switch for commutating a valve (102) to automatically control the supply of hydraulic fluid to the hydraulic cylinder at given moments of the machine's cycle.

Abstract: A hydraulically driven multicylinder diaphragm pumping machine has pump cylinders, each having at one end an inlet/outlet for fluid material to be pumped, and at the other end an inlet and outlet for hydraulic oil. A separator inside the pump cylinder is connected to the fluid-material end of the cylinder by a flexible diaphragm and to the fluid material end by another diaphragm, leaving an outer annular space that contains hydraulic fluid. The total volume of pumping hydraulic oil in the cylinders is maintained constant and by a device that compensates for thermal expansion and controls the necessary return flow of hydraulic oil for driving the pump. The separators move with an intake stroke at constant speed for all cylinders, and with pumping strokes function of the hydraulic oil delivery, so a lesser number of separators effect an intake stroke while a greater number of separators effect a discharge stroke.