Much of the wheel/rail damage is linked to the progression of wear on both wheels and rails. This progression changes the transverse shape of wheel and rail profiles, affects the wheel/rail contact conditions and thereby changes the mix of various forms of wheel/rail damage. Depending on the track curvature and the type and particulars of bogie design, each wheel/rail system may exhibit significant differences in steering and dynamic stability performance. Similarly the mix of wear, rolling contact fatigue (RCF) damage, RCF initiated defects, dynamic stability of bogies, corrugations of all types, and plastic flow (ratcheting and gauge corner collapse) may also differ significantly from system to system. The aim of the present paper is to analyse the influence of track curvature and bogie suspension on worn and unworn profiles and their effects on wheel/rail damage and on steering and hunting performance. It is demonstrated that reducing the spread between worn and unworn profiles can significantly improve curving and ride qualities of bogies. Replacing concave wear with a semi-concave wear pattern also has a significant effect in reducing the spread in rolling radius difference between new and fully worn wheel profiles. This has two consequences. Firstly, the semi-concave worn wheel, together with new wheels, remains conformal to rail profiles in curves and non-conformal to rail profiles in straight track. Thus, the wheel-flange/rail-gauge-face wear is not excessive and requires less lubrication. The tendency of bogies with worn wheels to hunt is also reduced. Secondly, the reduced spread contributes to the reduction or elimination of excessively large wheel/rail traction forces that are generated by rolling radius excess or deficiency. Keeping the magnitude of wheel/rail traction forces in the intermediate range provides good steering, while at the same time reduces the rate of wheel/rail material ratcheting and RCF crack initiation.
Wheel/rail damage and its relationship to track curvature
2003
6 Seiten, 6 Bilder, 3 Tabellen
Aufsatz (Konferenz)
Englisch
Wheel/rail damage and its relationship to track curvature
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