Multi-position measurement of oil film thickness within the slipper bearing in axial piston pumps

The oil film thickness represents the greatest unknown variable influencing the slipper performance in axial piston pumps. Earlier slipper test rigs suffer from two main drawbacks: inverse kinematics of the slipper and fixed measured positions. However, the real slipper behavior for one cycle should be examined from the standpoint of fluid film lubrication. Therefore, a new slipper test rig is designed to allow the multi-position measurement of oil film thickness within the slipper bearing under real operating conditions. This paper mainly includes a description of the slipper test rig and the developed multi-position measurement method. A group of three displacement sensors can capture the gap height between the slipper and the swash plate in thirty positions through an index plate mechanism. Finally, some sample results of oil film thickness are presented to confirm the capacity of the test rig.