A wheel profile survey has shown that significant numbers of wheels in North American freight vehicles have hollow shapes. A hollow shape is one where the profile at the center of the tread lies below the profile at the end-of-tread. Dynamic analysis demonstrates that a hollow wheel shape impairs the ability of a bogie to steer, causing increased rolling resistance and lateral wheel/rail forces. These lead to higher fuel use, accelerated rail wear, and damage to wooden sleepers. Hollow wear also leads to increased wheel/rail contact stress (which increases rail fatigue) and increased impact damage to switches and crossings. The conclusion from an economic analysis of the relative costs and benefits of removing wheels worn to a hollow shape is that the optimum economic removal criterion for North America is when wheels have reached 3-mm hollow wear. For the specific profiles studied here, this 3-mm limit corresponds to the development of a negative slope to the rolling radius graph, and consequent loss of steering. A proposal to introduce a rule for the removal of wheels worn to a hollow shape, for vehicles in interchange service, is under discussion by the North American railway industry. Finally, it is possible that small diameter differences between the two wheels on an axle lead to hollow wheel wear through the effect of diameter difference on vehicle stability in straight track.
The formation of hollow-worn wheels and their effect on wheel/rail interaction
2003
9 Seiten, 17 Bilder, 7 Quellen
Conference paper
English
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