Transient Traction Characteristics Between Rail and Wheel under Low Velocity and Low Slip Ratio: An Experimental Study Under Dry Condition

Transient traction characteristics between rail and wheel have been investigated with a rolling-sliding contact type of frictional machine under dry condition. The experimental results show the effects of contact pressure, rolling velocity, slip ratio, surface roughness and hardness, which have important influence, on the traction characteristics. Until traction coefficient reaches the peak after a test start, surface roughness and hardness decrease. During traction coefficient decrease after the peak, surface roughness and hardness increase rapidly by wear on the rolling-sliding contact surface. Moreover, it is thought that the primary factors, which traction coefficient increase immediately after a test start, are based on surface roughness, hardness, and boundary films (oxide film, reaction film, adsorbed film).