Rolling-sliding laboratory tests of friction modifiers in leaf contaminated wheel-rail contacts

Leaf-related low adhesion problems have been present in many railway networks all over the world in the last decades. One of the counter measures adopted by many railway networks is the use of friction modifiers. However, the effectiveness of these friction modifiers is not well proven yet due to the lack of research in controlled conditions. In this paper, a laboratory study of a widely used friction modifier is presented together with another adhesion enhancer designed for wet wheel-rail contacts due to rainfall. A twin-disk roller rig has been used to investigate their performance in leaf contaminated contacts. The adhesion characteristics of both friction modifiers were examined for different slip ratios. The constituents of the friction modifiers are identified and their suitability for leafy contacts is evaluated.