Preliminary Investigation on the Critical Point for Wheel–Rail Adhesion Recovery Phenomenon Under Water-Based Conditions

Under lubrication conditions such as water and anti-wear fluids, the wheel–rail interface typically demonstrates a low-adhesion state. More and more evidence suggests that the adhesion coefficient is not static but dynamically coupled with the rolling and sliding behaviors of the wheels. When the slip ratio between the wheel and rail is high, strong friction can greatly improve the rail surface condition, resulting in adhesion recovery. Nevertheless, experimental research on wheel–rail adhesion under high-speed and high slip ratios is lacking, and especially the critical point of adhesion recovery has not been clarified. This study investigates the adhesion characteristics at a speed of 400 km/h and analyzes the relationship between changes in adhesion and wheel surface temperature under high slip ratio conditions. The results suggest that there is a strong correlation between the wheel surface temperature and the critical point for adhesion recovery. Lubricants such as water and anti-wear fluids have a critical lubrication failure temperature, and once this temperature is exceeded, the lubrication state will be damaged, leading to an adhesion recovery phenomenon.