A Review of the Effects of Out-Of-Round Wheels on Track and Vehicle Components

Abstract Out-of-round rollingstock wheels are caused by skidding or spalling of the wheel tread and by dynamic motion of wheels and wheelsets in service. Out-of-round wheels generate impact forces at the wheel-rail interface, which are transferred to train and to track components including rail and both bolted and welded rail joints, prestressed concrete sleepers, ballast, wheels, and bearings. To make a rational decision about removing out-of-round wheels from service, estimation of the damage caused by an individual wheel is required. Previous studies have used analytical and numerical models to illustrate the distribution of impact into track and rolling stock components. These models are compared here. The review details mathematical models and studies of the lives of the earlier-listed components, which would provide a means of determining the damage caused by impacting wheels. In addition, studies have found that impacting wheels increase fuel consumption and increase pass-by noise levels, which are also discussed here. Further study of the effect of impacting wheels on axle bearing lives, parent rail, and bridges would improve this decision-making tool. It is envisaged that these models would be combined to determine the total cost of operating rolling stock with impacting wheels. This could be offset against the cost of wheelset maintenance to determine when an impacting wheel should be reprofiled.