Geometric design of axial piston machine slipper-bearings made of high-performance plastics

Abstract Oil hydraulic drivetrains are crucial in several industrial applications due to their high power density and dynamics, making them irreplaceable by electric drives. These systems consist of pumps that convert mechanical power into hydraulic power through pressure and volume flow, with axial piston machines being the most commonly used type. The performance and longevity of these pumps are largely determined by their tribological contacts, particularly the slipper-swashplate contact, which typically consists of a hard-soft material pairing of non-ferrous metal and hardened steel. Copper alloys are usually used, which are often alloyed with 0.1 to 23 % lead to improve malleability, corrosion resistance and emergency running properties. However, lead toxicity and copper’s role in accelerating oil aging raise environmental and cost concerns. This study explores the potential of replacing conventional brass slippers with tribologically optimized high-performance plastics. With an FEM-based geometry study several slipper design features are analyzed and their potential for wear reduction are discussed. The focus is on the design of the slipper socket and the attachment of a plastic running surface as well as its influence on the deformation of the running surface. In this context, both conventional non-ferrous metal and plastic slippers are investigated.