Mechanism Analysis and Optimization Directions of Metro Wheel Out-of-Roundness

With the rapid urbanization in China, the development of urban rail transit has accelerated, leading to increasingly prominent wheel out-of-roundness (OOR) issues in metro wheels. This problem severely compromises operational safety and maintenance costs. Through a comparative analysis of ER۸ and ER۹ wheels on identical routes, this study investigates the OOR mechanism from a materials science perspective, employing multi-angle mechanical testing, chemical analysis, and OM/SEM characterization of the wheel-rail contact zone. Experimental results reveal a critical threshold in wheel-rail hardness matching: below this threshold, no direct correlation exists between wheel hardness and OOR. Furthermore, plastic deformation and work hardening are observed in the wheel tread surface, with the severity of plastic deformation positively correlated to OOR progression. Additionally, frequent braking (≥۱۰ times/hour) is identified as a key contributor to OOR. Based on these findings, this study proposes a optimization directions for the wheel-rail system, focusing on improving wheel hardness and microstructural properties to reduce absolute wear, mitigate OOR, and extend wheel service life.

کلیدواژه ها:

Metro Wheel Out ، of ، roundness Mechanism Improvement