Eli5: Why train wheels don’t slip on the rails, when both the wheels and the rails are made of metal?

Question

Eli5: Why train wheels don’t slip on the rails, when both the wheels and the rails are made of metal?

In: 15

Answer 1

Friction: although both surfaces look smooth, there are minor imperfections that provide a little grip. Then, you’ve got the multi-tonne weight of the train pushing down on the wheel.