The wheel–rail interface is the area of contact between

wheel A wheel is a rotating component (typically circular in shape) that is intended to turn on an axle Bearing (mechanical), bearing. The wheel is one of the key components of the wheel and axle which is one of the Simple machine, six simple machin ...

s and

rails Rail or rails may refer to: Rail transport *Rail transport and related matters * Railway track or railway lines, the running surface of a railway Arts and media Film * ''Rails'' (film), a 1929 Italian film by Mario Camerini * ''Rail'' (1967 fi ...

railways Rail transport (also known as train transport) is a means of transport using wheeled vehicles running in tracks, which usually consist of two parallel steel rails. Rail transport is one of the two primary means of land transport, next to roa ...

. The interaction between wheel and rail is a specialized subject covering the design and management of the high stresses in the small contact area between a steel wheel and a steel rail. The focus is on safety improvement, maintenance and replacement costs reduction, downtime reduction, and energy and environmental management. The surface of the wheel that rests on the rail is known as the ''tread''. A wheel may have either a single flange on the gauge side of the rail or two flanges, one on each side of the rail.

References

Permanent way Train wheels {{Rail-transport-stub