Effect of Wheel Polygonalization on the Dynamic Characteristics of Gear-Transmission Systems of Urban Railway Vehicles

The gear-transmission system plays a crucial role in power transmission for urban railway vehicles. However, it can experience abnormal meshing conditions due to wheel polygonization, which presents a potential safety hazard for vehicle operations. To address this issue, the present study develops a dynamic model of an urban railway vehicle that integrates the gear-transmission system, simulating the effects of wheel polygonization on its dynamic behavior. The simulation results reveal that as the amplitude of wheel polygonization and vehicle speed increase, the vertical wheel–rail force, gear-meshing force, and dynamic transmission error (DTE) escalate. Furthermore, an increase in the order of wheel polygonization leads to a rise in the vertical wheel–rail force. In contrast, the gear-meshing force and DTE exhibit distinct trends at different speeds. At a speed of 20 km/h, these parameters increase by 51.34% and 0.29%, respectively. As the speed increases, the peaks of gear-meshing force and DTE occur at the 7th-order and 3rd-order polygon, respectively, suggesting that the dynamic response of the gear-transmission system becomes more sensitive to lower-order polygon effects at higher speeds, which necessitates greater attention during operation. Additionally, the phase difference of wheel polygonization exerts a significant influence on gear-meshing force under various conditions, such as in-phase, out-of-phase, 60° phase difference, and 120° phase difference. Therefore, in engineering applications, it is essential to consider the phase difference of wheel polygonization to alleviate excessive gear-meshing forces and ensure stable transmission performance. The findings of this paper offer insights into the dynamic evaluation and wheelset re-profiling of gear-transmission systems in urban railway vehicles.