A Study on the Prevention of Wheel-Climb Derailment at Low Speed Ranges

Wheel-climb derailment is considered to be profoundly influenced by the friction coefficient between the wheel flange and the rail. However, the coefficient varies greatly according to the surface condition of a wheel and rail, atmospheric conditions, and the frequency that a wheel passes over the rail. And it is also deemed to be hard to directly measure the coefficient as the process of derailment has not been made clear yet. Wheel-climb derailments were achieved by the authors using EMUs in practical use equipped with newly turned wheels. To find the cause of the derailments in the experiments, the EMUs were repeatedly operated on a sharp curve track and such values as the derailment coefficient, the attack angle of the wheel to the rail and the wheel lift-up value from the rail were continuously measured under the critical wheel-climb conditions. The results of the experiments are reported in this paper.