IIRC, San Juan makes O-scale and P:48 trucks with working brakes. Unfortunately no roller-bearing trucks tho. :'(
Ed
I was unable to fit working brakes on the San Juan site. I also could bot find wood beam trucks appropriate for ACW.
I have never seen a set of working air brakes on Z through O scale model car, though Randy Anderson of Hagerstown did make a few cars with working hand brakes in HO scale. These where 50s era freight cars, with much more complicated rigging than mine. Randy's freight cars are amazing. He gave me a tour of his shop once and showed me all the specialized tools he developed to make master models of HO cars. He may have the best HO freight car fleet that I know of.
The beauty of my ACW cars is that the brake mechanism in the 1860s was very simple and was only on one truck per car. It is not that hard to do.