No text, but a visual code

[Rafal]

and anyone knowledgeable about medieval astronomy and astrology will recognize it immediately.

Sorry Antonio but this is a manipulation.

You claim there would be some universal consensus among all "experts" while you have never done such a poll.
You also set a subtle trap - if I don't agree with you then I am just incompetent.
And then I have to struggle and prove that I am somehow competent while you made your claims without proving anything.

I am not going for it, try your tricks with someone else 

By the way, I agree it is rather not a working clock. The 24 marks which would in theory make hours are set not equally but in groups of three ones. But this argument works against volvelle as well.

For me it could be some symbol, maybe actually meaning trine as you say. But not a realistic, working volvelle.