Effects of axle load transfer on wheel rolling contact fatigue of high-power AC locomotives with oblique traction rods

Abstract Severe wheel rolling contact fatigue (RCF) has been observed on two types of high-power AC locomotives with CO-CO axle arrangement and running in complicated environments in China. This RCF occurs as continuous lateral surface cracks in the zone approximately centered at the nominal rolling circle of wheels and can propagate downward up to 14.5 mm deep. To figure out the causes, field observations, monitoring tests and numerical simulations have been conducted in the past years together with systematic comparisons between two types of locomotives. Statistics have shown an interesting phenomenon, among others, that wheels on axles 3 and 4 are most susceptible to RCF cracks on Type B locomotives, but not so on Type A. It has been found that complicated running environments such as sharp curves and large slopes are the root causes of RCF. The axle load transfer among axles, which is aggravated by oblique traction rods, and inappropriate electrical compensation, and the curving behavior determine the axle preference of RCF on Type B locomotives. This explains the phenomenon that similar RCF damage has not been reported on Type B locomotives running in mild environments. At the end, the electrical compensation is optimized numerically with a purpose of easing RCF damage of Type B locomotives.