In the paper, the author analyses a model of a ring pack motion on an oil film. The local thickness of the oil film can be compared to the height of the combined surface roughness of a cylinder liner and piston rings. Equations describing the mixed lubrication problem based on the empirical mathematical model formulated in works by Patir, Cheng [6, 7] and Greenwood, Tripp [3] have been combined [13] and used in this paper. A model of a gas flow through the labyrinth seal of piston rings has been developed [14,16]. In addition, models of ring twist effects and axial ring motion in piston grooves have been applied [15,16].

In contrast to the previous papers of the author, an experimental verification of the main parts of developed mathematical model and software has been presented. A relatively good compatibility between the experimental measurements and calculated results has been achieved.