A reciprocating positive displacement pump is disclosed for pumping oenological liquids such as wines, musts, distillates, vinegars and the like, alimentary oils and other alimentary liquids and/or beverages such as fruit juices and pulpy and sugary juices. The pump is of the kind which has a reciprocating piston and distributing ball valves utilizing rubber-covered balls, and comprises a double-action hydraulic cylinder for actuating the piston, the hydraulic cylinder being fed by a central distribution unit which is in turn fed by a source of presurized fluid. The piston has a cam member mounted to its stem. The cam member is movable between contact with two limit switches upon reciprocation of the piston so as to cause direction reversal of the piston. Further, a rotating member can be provided in contact with the cam member, so as to rotate the cam member and thus, the piston stem and piston.