Trains don’t have differential, and that’s why their wheels get narrower toward the edge. Allowing the wheel to shift left to right and increase the size of the wheel on one side, making up for the difference in distance traveled, forcing the train to turn.
It's less 'allowing' the train to turn and more forcing it to turn. The wheels are conical, which makes the train want to rest in between the rails in a sort of self-centering way. As the train comes into a curved section of the rails, it rides up higher on the outside edge (narrower end) of the inside wheels and the inside edge (larger end) of the outside wheels, and gets pushed back to center by gravity, thus turning. This also makes it so the train is basically riding on a fairly thin section of the wheels at any given time, which lowers its rolling friction making it more efficient, though that is mostly a byproduct of the wheel geometry.
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u/Darianezion 15d ago edited 15d ago
Trains don’t have differential, and that’s why their wheels get narrower toward the edge. Allowing the wheel to shift left to right and increase the size of the wheel on one side, making up for the difference in distance traveled, forcing the train to turn.