APPOS - Final report

Most of the power losses in a hydraulic pump come from the friction between parts in relative motion. In order to achieve hydrodynamic lift, leakage of lubricant is necessary, with a detrimental effect on the overall efficiency. Hence, surface treatments able to reduce friction and enhance efficiency in such devices are extremely interesting. In the Reference project we have demonstrated that when the slippers of axial piston pumps are modified by the deposition of properly designed oleophobic coatings on their surface, the friction coefficient can be lowered of about 30% at low working pressure and low rotational speed, e.g. when the hydrodynamic lift is harder to achieve and the efficiency is the lowest. Owing to these findings, this project aims at the design and realization of a prototype of axial piston pump featuring different functionalized components, namely slippers, swashplate and valve plate. We are expecting to observe a synergistic effect of the surface coated components in reducing friction and increasing the overall efficiency in hydraulic pumps.