3-piston alternating volumetric pumps for use on cleaning units and industrial systems. Can be coupled to various types of motors, directly or with flexible joint. Pump body in die-cast aluminium alloy. Side cover may be blind. Pistons driven by crank-connecting rod mechanism. Pump shaft in pressed high-strength steel. Oversized friction bearings. Connecting rods in die-cast special low-friction zinc-aluminium alloy. Bronze connecting rods available. Pump head in pressed brass. Double gasket sealing system. Delivery valves have plugs for easier maintenance. Regulator valves built-in to the pump head, with detergent injector.