I have a drawing, I will post it tomorrow. It is the old Schurz valve that was bought by Fleck 25-30 years ago. I am guessing Fleck bought them for the hot water plastic. The plastic was almost instantly used for the Fleck 3600, the Schurz valve was discontinued. history class is over.
It was a 2 cycle valve, Brine and Slow rinse only with upflow regeneration. The valves were amazingly cheap to rebuild, I think the whole rebuild kit was under $10. They took about 2 minutes to rebuild, and they worked by simply opening the drain line. Anyway, I am writing a short article on water softener cycles and would like to include n actual picture of one rather than an old drawing from a copied manual I have from 1985.