Within the Collaborative Research Center 442 “Environmental friendly tribological systems“ components of different tribological systems are applied with PVD-coatings to realize the performance of these systems with biologically fast degradable fluids without increased friction and wear. With the usage of biologically fast degradable fluids without environmentally toxic additives some essential functions, that had been given by the former fluid, have to be substituted, what is realized by the provision of sliding parts with coatings. By that way wear and friction are decreased significantly. In this paper it is shown, that coated pistons of an axial piston machine reveal limited wear within the first hours of operation and very low friction between piston and bushing. The experiments are made on an one piston test bench

Keywords: carbon, coatings, PVD, hydrostatic displacement unit, wear, friction