There is nothing "new" in that air brake setup. That's an old #8 air brake system. Parts for that system are no longer made, stocked or even cared about. I hope UP has a good stock of #8 brake valve parts on hand, because no one else has any.
Almost every other steam locomotive operator in the country has changed over to a modern, pressure maintaining, #26 air brake system. Replacement 26 brake valves are available in every diesel shop in the country.
Using this old air brake system makes no sense to me at all.