5. Bearing maintenance

Wheel and flange profiles are subject to wear for a variety of reasons:

• in the tapered part of the bearing, friction in contact with adhesion, which leads to deterioration of the surface finish through deformation and removal of material;

• braking force, when applied by means of brake shoes rubbing on the wheel profile;

• parasitic axle movements, particularly yawing, which accentuate wear, but do not significantly degrade the slope value;

• crossing curves in the track, which, if accompanied by guiding contact on the flange, cause wear and therefore thinning of the flange;

• the crossing of switches and crossings, which causes contact between the inner face of the flange and the guide rail