What turns train wheels?

You know, it's funny... I used to wonder about that too! What does make those massive train wheels turn on a curve? I mean, they're huge, solid metal things, right? It seemed almost impossible. For the longest time, I pictured some elaborate system of gears and levers underneath, all whirring and clanking away. Turns out, I was way overthinking it. It's the wheels themselves! They're conical – slightly slanted. So, when the train hits a curve, the outer wheel, the one on the outside of the bend, actually travels a longer distance because the larger diameter part of the cone makes contact with the rail. Meanwhile, the inner wheel, kind of shrinks, in a way, because the smaller diameter part of the cone touches the rail. Think about it – a longer path on the outside, a shorter path on the inside… Isn't that brilliant? Like, how did someone even figure that out?! I remember once watching a train go around a bend, a really sharp one, and you could almost see the difference in how the wheels were working. It's subtle, but it's there. This whole thing, it's like… a forced perspective trick, but with physics! It still feels a little bit like magic to me, even though I know the science behind it. Pretty cool, huh?