3-piston alternating volumetric pumps for use on cleaning units and industrial systems.Pump body and cover in die-cast aluminium alloy. Side cover may be blind or incorporate oil sight glass. Rear cover with oil drain outlet. Pistons driven by crank-connecting rod mechanism. Pump shaft in pressed high-strength steel. Oversized friction bearings. Bronze connecting rods. One-piece ceramic pistons. Pump head in nichel – plated brass. Double gasket sealing system. Intake and delivery valves have plugs for easier maintenance.