Experimental evaluation of amount and repeated applications of top of rail friction modifiers on wear and adhesion

Abstract

ABSTRACT A laboratory evaluation of top-of-rail friction modifiers (TORFM) is conducted to evaluate their effect on wear and adhesion, in settings that are closer to field conditions. The study, which uses the Virginia Tech-Federal Railroad Administration (VT-FRA) roller rig, extends past tribological studies with twin disks. Separate tests are performed in two phases. In Phase 1, the effect of TORFM volume, ranging from light to heavy applications (about 1 to 25 μm layer thickness), is evaluated on wheel wear. The normalized results indicate that light applications of TORFM yield the most favourable wear-to-cost ratio. In Phase 2, TORFM effectiveness duration is evaluated by applying the material in multiple cycles and monitoring the time-lapse for adhesion to recover to the unlubricated condition. Repeated applications of TORFM in moderate amounts (5 μm layer thickness) could lead to a stick-slip phenomenon that could not only diminish adhesion but also lead to surface markings on the rail.