Abstract
In hydraulic systems with pressure levels above 21 MPa, as being typical in mobile applications, piston units are the first choice. Especially axial piston pumps in swash plate design offer technical benefits and enable compact and efficient designs. Worth mentioning here as an example is the power take off (PTO) and the efficient controllability by use of variable displacements. Nevertheless, the tribological contacts in these robust and widely used components are highly stressed and determine the efficiency of the units. Due to the kinematics each piston is highly loaded by lateral forces and therefore the piston-bushing contact represents the area where the tribological knowledge is essential for wear-resistant and efficient design. Besides materials, macro and micro geometry, local loads and movement lead to friction losses. This paper describes the theoretical kinematics of the inclined piston and a sensor for measuring the rotation of the piston in the pressurised piston-bushing contact, which enables to fill the knowledge gap regarding the rotational movement of the piston under operational conditions.
