Out-of-round railway wheels and polygonisation

Out-of-roundness in railway wheels, particular polygonal wear resulting regular, multi-lobed, out-of-round has become a significant problem recent years. It is of concern to operators due the increased noise and vibration it can cause. This polygonisation caused by cyclic but exact mechanism leading this type not fully understood. appears be result dynamic linking between resonance or other periodic excitation coupled vehicle–track system existing at wheel. paper reviews developing body research being carried out many countries groups, manufacturers operators. Some examples on different types vehicles are reported including feight trains, urban transit trains high-speed trains. The main theories for formation mechanisms presented current measurement methods, computer simulation techniques effects potential mitigation methods reviewed. In parallel, consequences discrete wheel tread irregularities, such as flats material fall-out rolling contact fatigue cracking, addressed.