Steel wheel bearing – Steel rail
Railway rolling -mechanical aspect of traction

The railway bearing is a combination of two components:

• the steel wheels that make up the axle;

• the two rolling and guiding tracks, also made of steel.

The profile of the wheels is conical, with a half-angle at the apex α, enabling each wheel to travel the different lengths of each rail line in a curve by positioning itself on the corresponding diameter of the cone. The wheels are fitted with a circular shoulder called a "flange", of width b, helping to guide the axle. The bearing geometry is shown in figure 1 (see also