The Motion of a Railway Axle

Abstract

The authors investigated the motion of a single axle and pair of wheels by means of a model, paying particular attention to the action of the flanges and to their influence on the development of “hunting”. In justification of the use of a single axle, evidence is produced that, owing to the various clearances, the axles of a bogie are in fact largely free to follow their individual paths. The effects of unsprung mass, wear of tyres and rails, flange clearance, lateral stiffness of the track, and other variables were studied. It is shown from considerations of dynamical similarity that the speed at which oscillation of a given violence occurs varies approximately inversely as the square root of the unsprung mass, and that a reduction of this mass would therefore be beneficial. Possible changes in tyre profile are discussed.