Abstract: Pump having an inlet through which passes a medium intended for pumping, and an outlet through which passes the pumped medium. A drive source acts upon a number of pumping organs, said pumping organs being arranged in pairs as to be actuated by at least two rotable shafts, in addition to which pairs of pumping organs are arranged by means of communicating vessels and are driven by a cam on each shafts. Four rotable shafts (10, 20, 30, 40) are so arranged as to each interact with four pumping organs each. A pumping unit of 16 pistons are thus created. Several pumping units can be added together into one pump.