Radiator hose valve?

[Thearne3]

I was at the national car and truck museum in Auburn Indiana yesterday. They had a model a chassis cutaway exhibit. Here is a link to the pictures I took – I’ve never seen such a good display with every component having a cutaway view.

https://photos.app.goo.gl/NZDWXNoHLA9xd3Lz5

In the upper radiator hose, there was a device that seemed to be a check valve which was spring operated. I’ve never seen anything like it. See the pictures below.

Thoughts?