On the Time-Dependent Spin Creep of a Railway Wheel

Abstract

This paper describes two theoretical calculations of the fluctuating spin creep of a railway wheel rolling on straight track. The first calculation is of the transient spin moment which occurs when a constant spin creep angular velocity is applied suddenly to a rolling wheel. This may occur, for example, when a wheel passes over a discontinuity in the rail and rolling contact is resumed suddenly. The second calculation is of the fluctuating spin creep moment which occurs when a coned railway wheel rolls along a slightly corrugated rail. The analysis is highly idealized, using the approximations of the simplified theory of Kalker and assuming that the area of slip is limited to a negligible proportion of the area of contact. In the first calculation, the area of contact is assumed to be circular; in the second calculation, it is assumed to be rectangular. Subject to these far-reaching assumptions, the results of the calculations suggest that oscillatory fluctuations in spin creep may be initiated by rail discontinuities and irregularities. Such oscillatory fluctuations in conditions at the contact patch may have a role in the development of rail corrugations.