That is interesting. I had not seen this before. I was looking at the pictures figuring out the movement and asking myself how does it manage to move the pad toward the rim. Then I saw the last picture. Clever, but probably not very good.

If I had them on a vintage bike, I would replace the pad material with pads from Kool Stop and use it. How bad could it be? It has the right motion, perhaps not the right leverage, but that would also depend upon the lever.

So, maybe this arrangement works perfectly good with the right lever and pad?