STUDY OF LUBRICATION CONDITIONS IN SLIPPER-SWASHPLATE CONTACT IN WATER HYDRAULIC AXIAL PISTON PUMP TEST RIG

Abstract

In water hydraulic systems, requirements for better energy efficiency call for the development of variable displacement axial piston pumps. Most axial piston units utilizing water as pressure medium lack the possibility of adjusting the swash plate tilt angle. because of difficulties in constructing robust water compatible swash plate pivot bearings. Without smooth enough adjustment motion, the lubrication conditions between the swash plate and the piston slipper pads become disturbed and loss of fluid film may lead to early pump failure.This study reports on measurements made with a test rig built for investigating tribological phenomena in variable displacement axial piston pumps. In the tests, the effects of changing the swash plate tilt angle were measured in a test setup with constant high pressure which loaded the piston. Lubricating film thickness and lateral force acting on the piston were measured together with changes in these quantities in response to changes in swash plate tilt angle.