TRIBOLOGICAL INTERRELATIONSHIP OF SEASONAL FLUCTUATIONS OF FREIGHT CAR WHEEL WEAR, CONTACT FATIGUE SHELLING AND COMPOSITION BRAKESHOE CONSUMPTION

This paper proposes a novel theory which explains the strong linkage b etween brakeshoe metal pick-up and a corresponding increase in wheel t read wear and shelling during the wet winter months, The model suggest s that pick-up metal forms through the tribe-reduction of oxidized whe el-rail wear debris. The presence of abundant carbonaceous residues an d moisture is thought to promote this reaction. The consequent removal of carbon and wear debris from the wheel-rail interface increases fri ction during the dry periods to the range 0.4-0.6. This exacerbates wh eel-rail wear and shelling. It is concluded that the most effective wa y to alleviate seasonal increases in wheel shelling and wear is to con trol friction in the range 0.2-0.4. This can be accomplished by inhibi ting carbon depletion associated with metal pick-up or by applying com mercial friction reducers.