How do they avoid “clack-clack” sounds on high-speed trains? Are the rails made without gaps? And how do they manage thermal expansion then?

Question

How do they avoid “clack-clack” sounds on high-speed trains? Are the rails made without gaps? And how do they manage thermal expansion then?

In: 1047

Answer 1

It’s the same as the effort to reduce noise for transmission gears. Instead of having the teeth engage perpendicularly, they’re [angled](https://upload.wikimedia.org/wikipedia/commons/6/61/Gear-kegelzahnrad.svg). In the case of rails, the joint is [like this](https://i.ytimg.com/vi/Fc0GeJX5ltg/maxresdefault.jpg).