Tribological interrelationship of seasonal fluctuations of freight car wheel wear, contact fatigue shelling and composition brakeshoe consumption

Abstract

This paper proposes a novel theory which explains the strong linkage between brakeshoe metal pick-up and a corresponding increase in wheel tread wear and shelling during the wet winter months. The model suggests that pick-up metal forms through the tribo-reduction of oxidized wheel-rail wear debris. The presence of abundant carbonaceous residues and moisture is thought to promote this reaction. The consequent removal of carbon and wear debris from the wheel-rail interface increases friction during the dry periods to the range 0.4-0.6. This exacerbates wheel-rail wear and shelling. It is concluded that the most effective way to alleviate seasonal increases in wheel shelling and wear is to control friction in the range 0.2-0.4. This can be accomplished by inhibiting carbon depletion associated with metal pick-up or by applying commercial friction reducers.