TWIN-DISC ASSESSMENT OF THE EFFECT OF TOP-OF-RAIL FRICTION MODIFIERS ON THE TRIBOLOGICAL RESPONSE OF ER8-R370HT PAIRS FOR USE IN WHEEL-RAIL SYSTEMS

EVALUACIÓN MEDIANTE ENSAYOS DISCO-DISCO DEL EFECTO DE LA ADICIÓN DE MODIFICADORES DE FRICCIÓN SOBRE LA RESPUESTA TRIBOLÓGICA DE UN PAR ER8R370HT PARA USO EN SISTEMAS RUEDA-RIEL

Abstract

This paper studies the effect of the addition of top of rail - friction modifiers (TOR-FM’s) on the tribological response of a rolling-sliding pair submitted to similar conditions to those found in commercial wheel-rail systems. The tests were conducted in a wheel-rail contact simulator (twin-disc machine) and the samples were extracted from worn wheels and rails provided by Metro de Medellín (Colombia). The tests were carried out using two Friction Modifiers. Dry tests were also performed for reference purposes. TOR-FM1 was a commercial friction modifier and TOR-FM2 was developed in the laboratory for the operating conditions of Metro de Medellín. The Hertzian contact pressure was 1 GPa and the average roughness (Ra) before the tests was fixed at 1.3 µm. The addition of friction modifiers at the interface reduced the Coefficient of Friction (COF) when compared to the dry condition, improved the surface quality and reduced the depth of the deformed material layer under the contact surface