Influence of wheel flat on railway vehicle helical gear system under Traction/Braking conditions

Abstract

The gear system is an essential component of railway vehicles. However, wheel flat often affects the gear system's fault diagnosis and fatigue life and further jeopardizes vehicle operation safety. This paper develops a railway vehicle model equipped with a helical gear system. The model validation uses the experimental data under various operating conditions. The discussion of the simulation results involves the time-domain and time–frequency domain responses of the gear system of a vehicle with the wheel flat under variable speed conditions. Simultaneously, the analysis of its regularity uses the peak-to-peak value as characteristic vibration indicators. The results show that the wheel-rail contact status has two regions: the continuous contact region and the intermittent contact region. The vibration of the gear system is relatively stable in the continuous contact region. However, it fluctuates sharply in the intermittent contact region. In the time–frequency domain results, the fundamental frequency of the wheel flat and its multiplier gradually replaces the healthy gear meshing frequency and its multiplier as the primary contributor to energy. Furthermore, the peak-to-peak value shows that the gear system vibrates significantly under critical conditions. The above results can help improve the gear system's stability and thus the running stability and safety of railway vehicles.