The design's been the same for as long as I can remember. Unscrew the dustcap and you get a little knurled nut which also needs unscrewing before you can pump the tyre up. and after pumping, you screw it back up again.
And, if you're a bit hamfisted like me, the central screw thread gets bent. Still works, mind. No big deal.
Then it snaps off, and you need a new tube.
I never got round to getting one. 5 years ago this happened; I have to depress what remains of the central screw in order to enable air ingress. The air pressure forms a seal which isn't easily broken.

One might reasonably ask if the design ought to be simplified after all this time . . . .