Experimental Investigation of New Design Concepts for the Tribological Contact between the Valve Plate and the Cylinder Block in Axial Piston Machines


  • Stefan Geffroy
  • Stephan Wegner
  • Stefan Gels
  • Katharina Schmitz




Axial piston pump, cylinder block, pressure pocket, tilting


Axial piston machines are widely used in both stationary and mobile hydraulic systems due to their efficiency and robustness in high pressure applications. Important tribological contacts in axial piston machines are between pistons and bushings, sliding shoe and swash plate, as well as between cylinder block and valve plate. The analysis of these contacts is imperative to improve the overall performance of the machine, since they influence its efficiency to a high extend. This paper focuses on the contact between the valve plate and the cylinder block. High pressure forces acting on the cylinder block result in a tilted position, defining the shape of the interface with the valve plate. The tilted position is overlayed by the cylinder block’s rotation, resulting in unfavorable lubrication conditions and high contact pressure.

Measures to actively influencing the cylinder block’s position during its rotation is currently researched at ifas. Using pressure pockets in the kidney grooves of the cylinder block is one of these measures and presented in this paper. The investigation is done simulative and experimental, using a 140 cm³ pump on a special test rig, measuring the cylinder block movement. The results of this are presented in this paper.