inox_ionizer 说:
Okay, answer this: How does a train turn without having the things between the wheels break and twist? Best answer earns 1 silver star. Thanks.
Good question! As we all know, the outer part of the railway is longer than the inner part, but the wheels are connected to each other and must therefore have the same amount of rotations per time unit. How did the train dudes solve this? It's pretty brilliant. Take a look at this picture of train wheels:
The widest "disc" is there to hold the train in place, the part outside it is the one rolling on the rails. If we had placed these wheels on a railway, we would be able to see that there is a small gap between the rail and the widest "disc" on the wheels. That allows the train to move a bit sideways, which can be controlled by adjusting the railway.
What we can see on the picture, is that the part rolling on the rails is not sylindrical; it narrows down outwards. This means the radius varies, and thus also the circumference. The outer part can travel a shorter distance than the inner part in the same amount of time. So there you go; the circumference of the part of the wheels that touches the rails can vary in relation to each other, thus making them travel at different speeds.
Bonjour, baguette.