Influence of fine unevenness on wheel tread on tangential force characteristics of wheel/rail interface under wet condition

Abstract

It is generally known that the groove on tire tread can increase the friction force between the tire and the road surface under wet condition because of the improvement of drainage performance. Although wheel tread of actual railway rolling stocks has a machined contact surface like the groove on tire tread, the characteristics of tangential force of the wheel/rail under wet condition is not clarified in detail. In this study, the tangential force measurement using a pair of small cylindrical specimens was carried out to investigate the relationship between the machined contact surface and the friction force under wet condition. The experimental result shows the friction force under wet condition does not increase due to high iron’s stiffness if the machined contact surface provided on the tread. On the other hand, it is also confirmed that the machined contact surface has a reduction effect of the variation of the friction coefficient under wet condition. From the numerical analysis based on these experimental results, it is clarified that the longitudinal vibration of the vehicle can be decreased if the wheel has the machined contact surface in case of the braking running under semi-wet-condition.