What does a ‘flange’ refer to in rail terminology?

In rail terminology, a 'flange' refers specifically to the protruding edge of a train wheel. This feature is crucial for maintaining the stability and alignment of the train on the track. The flange allows the wheel to guide itself along the rails, preventing derailment by ensuring that the wheel remains within the track's confines. This design is fundamental to rail vehicles, as the interaction between the wheel flange and rail plays a critical role in safe and efficient travel.

Understanding the function of the flange emphasizes its importance in rail mechanics and vehicle operation, highlighting how it directly impacts safety and performance. In contrast, the other choices pertain to different components of the rail system, such as the main body of the rail, the joint between rail segments, and the meeting area of tracks, but they do not specifically define the flange as a wheel feature.