Analysis of Traction Coefficient Subject to Rail Cleaning Effect Based on Tribomachine Measurements

The proper representation of friction contact conditions between each wheel and the rail is necessary to accurately model the behaviour of a heavy haul locomotive since friction conditions at the wheel-rail interface affect the locomotive's dynamic performance under traction and braking conditions. In normal operations, a phenomenon commonly known as rail cleaning effect occurs. The rail cleaning effect causes increased friction coefficients between the following wheel treads and the rail head. The wheel-rail interaction causes the third body layer to be partly or wholly eliminated from the surfaces in contact and generates new layer. An experimental analysis of the changes in friction coefficients under simulated locomotive wheel-rail contact conditions, in terms of contact pressure and slip, is presented in this paper. For this study, data processing equations are presented to obtain the experimental traction coefficient and slip. Furthermore, the rail cleaning effect is examined under different slip conditions. The experiment shows the traction coefficient increases for a given number of cycles until reaching a steady value, demonstrating that the rail cleaning effect is measurable in various slip conditions on a twin disc machine.