How Do Trains Stay on the Tracks?
Quick Answer
Trains stay on the rails mainly because their wheels are slightly cone-shaped, which automatically steers them back to the centre; flanges act only as a backup.
The Full Story
Train wheels on each axle are fixed together and their treads are tapered, wider near the inside. If the train drifts to one side, the wheel on that side rolls on a larger diameter while the other rolls on a smaller one. The larger wheel travels further per turn, steering the axle back toward the centre. This self-centring effect also helps trains go round curves without the wheels skidding. The flange, a raised lip on the inner edge of each wheel, only touches the rail on sharp curves or as a last line of defence.
Key Facts
YouTube Angle
Suggested video title for this topic:
"The clever wheel shape that keeps trains on the rails."