The effect of Subzero temperature and snow on the tribology of wheel-rail contact

The wheel-rail system operates in an open environment where the weather condition varies constantly. In this laboratory study, an investigation using a pin-on-disc tribometer placed in a temperature-controlled room was conducted to examine the effect of subzero temperature and snow on friction and wear at the wheel-rail contact. In temperature range from 3 to-15 °C (without snow) friction and wear were dominated by low temperature brittleness, which led to an increase in friction and wear. When temperature decreased down to-25 °C, an ice layer condensed on the pin and disc surfaces, which then melted during sliding and acted as a lubricant, leading to the sharp decrease of friction and wear. When snow crystals were added into the contact they melted into water droplets during sliding because of pressure melting and reduced the friction and wear following the boundary lubrication mechanism. With increasing temperature from-25 to 3 °C, friction performed monotonously decreasing because of the increasing thickness of the water layer. A large area of oxide flakes generated on the worn surfaces also significantly protected the contacting wheels and rails from severe wear.