Abstract: The adhesion experiment of wheel/rail under different medium conditions is investigated by a MMS-2A testing apparatus. The effects of dry condition, water, oil, sand and leaves on adhesion coefficient of wheel/rail are explored in detail. The results indicate that the adhesion coefficient of wheel/rail is different under different medium conditions. The maximum adhesion coefficient is found under dry condition. The adhesion coefficient is smallest with mixed oil and water. Adding water and oil can remarkably decrease adhesion coefficient of wheel/rail. Furthermore, the adhesion coefficient under oil condition is smaller than that of water condition. With the humidity increasing, the adhesion coefficient of wheel/rail would decrease. When the humidity increases from 20% to 100%, the fall of adhesion coefficient is about 17%. With an increasing axle load, the adhesion coefficient of wheel/rail increases under dry, oil and water conditions. Adding fresh leaves to contact zone causes a drop of the adhesion coefficient of wheel/rail. The adhesion coefficient is smallest under leaves and water condition. Sanding can increase adhesion coefficient of wheel/rail under water and oil conditions. However, sanding can aggravate the spalling damage of wheel/rail surfaces.

Key words: Adhesion coefficient, Oil, Sand, Water medium, Wheel/rail