External Gear Pumps and Motors Bearing Blocks Design: Influence on the Volumetric Efficiency

External gear pumps and motors, in their typical commercial design, are equipped with hydraulically balanced bearing blocks, which allow to maintain good volumetric efficiencies also when the pressure drop between the ports is high. The aim of this work is to analyze some geometrical aspects characterizing the bearing blocks design, evaluating their influence on the volumetric efficiency of the machine with the aid of a numerical model properly created. External gear pumps and motors operation behavior is strongly influenced by the volumetric efficiency; this parameter takes into account the leakages of fluid which typically affect the hydraulic machine operation and, together with the mechanical efficiency, determines its total efficiency and, consequently, has a great influence on power loss.