Railway wheel

Figure 8-22. Examples of similarity symmetry (photographs by the authors). Top-. railway wheels, Foundry Museum, Budapest Bottom mountain goats, Budapest Zoo.

Design of railway wheels were indeed challenging as they ran on rails. In the beginning of nineteenth century, rack-type tracks were developed on which a toothed wheel moved. However, it was difficult to use toothed wheels on rails. It took considerable efforts and experiments in the design of wheels for rails to realize that smooth rails in contact with the wheel rim could give sufficient friction to run the trains. Two types of wheel-rail combinations were initially used—flanged type... 

S.1. HeatTreatment of Railway Wheels. This treatment requires a toughness that combines a very long wheel life with a tire that must be much harder than the rest of the wheel. This requires that the tire be quenched and then tempered to prevent brittleness and to have the proper hardness. 

However, when one describes the adhesion of a tire to a road surface or of a railway wheel to a steel rail, as in Fig. 2.2(b), this means something entirely different. In fact, there is no significant adhesion force in this case as one tries to lift the wheel from the track. Instead, the writer is referring to the force required to make the wheel skid along the surface. This phenomenon should be called friction and not adhesion. If the railway was built on the surface of the Moon, however, there could well be significant adhesion then between wheel and rail because the surfaces are much cleaner, giving improved contact. Friction would then also increase. 

The JKR theory was developed in the early 1970s to account for the adhesion between spherical bodies, especially fine particles (see Powder Adhesion), making elastic contact. Previously, most studies of elastic contacts had presumed that bodies like steel railway wheels behaved as though adhesion was zero. In other words, no adhesion interaction seemed to be acting in most engineering contact situations. Negligible adhesion force is generally detected as a wheel is lifted from a rail, and the size of the contact spot between wheel and rail can usually be predicted accurately from the laws of elastic deformation, without any molecular attractive forces. 

Skarlatos, D., K. Karaksis, and A. Trochidis. Railway Wheel Fault Diagnosis Using a Fuzzy-Logic Method. Applied Acoustics 65, no. 10 (2004) 951-966. 

Incorporating a Railway Wheel Wear Model into Multi-Body Simulations of Wheelset Dynamics... 

A model has been developed to predict the wear of railway wheels. The wear modelling approach is based on a wear index commonly used in rail wear predictions. This assumes wear is proportional to Ty, where T is tractive force and y is slip at the wheel/rail interface. Twin disc testing of rail and wheel materials was carried out to generate wear coefficients for use in the model. 

The modelling methodology for predicting the evolution of a railway wheel profile consists of four main elements ... 

Figure 1. Railway Wheel Wear Modelling Scheme...

The model has been incorporated into ADAMS/Rail, which produces multi-body dynamics simulation of a railway wheelset. The methodology for predicting the evolution of a railway wheel profile is made up of three stages ADAMS/Rail outputs contact... 

Lewis, R., Dwyer-Joyce, R.S., Kapoor, A., "Wear Mechanisms in Railway Wheel Steels", in press. 

Kalker, J.J., "1991, "Simulation of the Development of a Railway Wheel Profile through Wear", Wear, Vol. 150, pp355-365. 

Paper IX (v) Incorporating a Railway Wheel Wear Model into Multi-bodv Simulations of Wheelset Dynamics by Mr A Ward, Dr R Lewis and Dr R S Dwyer-Joyce (The University of Sheffield, Department of Mechanical Engineering, Sheffield, UK). 

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