The effect of hollow-worn wheels on vehicle stability in straight track

A significant number of wheels on North American freight vehicles are worn to a hollow shape. Anecdotal evidence is that such wheels make vehicles more prone to vehicle instability, known as “hunting.” Through modelling and testing, this paper examines the effect of hollow wheels on wheel/rail contact geometry and hence on vehicle stability. It is concluded that hollow wheels do not promote hunting, but can produce vehicle lateral accelerations approaching those caused by hunting. The paper also demonstrates that wheel-to-wheel relative diameter measurements on the same axle are of great importance when modelling vehicles with measured worn wheels.