“Oh Bother,” Said Pooh, as he examined once again the lone photo of Canada Atlantic coal cars. The photo is barely worth looking at, they’re so distant, but comparing to other cars nearby, Pooh was pretty sure they had brake beams slung from the truck transoms, rather than slung from the underframe outside the trucks.
Well, I knew it would have to be done one day because the Pullman-built box cars had inside brakes too. So, I set about adding an inside-braking option to the 3D model. The output is shown. Can you imagine trying to make a mold of this part? Supporting it for 3D printing is going to be challenging, but at least possible (I think!).
This is a bit interesting to me because having worked at BC Rail through the transition period of friction to roller bearings gave me the opportunity to have an often intimate look at car and truck brake rigging. You are mostly concerned with arch bar trucks, I never played with em, but the newer cast steel ones lots of times, changing wheel sets was a grimy job. The brake beams were hung with a rectangular steel loop, on the beam itself there is a pocket behind the brake shoe for the bottom of the loop. The top of the loop if I recall hung from the truck bolster with a key keeping it in place. The rod and levers you show do take me back to those dark wet afternoon shifts on the RIP track. Things got cleaner and simpler with roller bearings where the ends of the brake beams extended out to slide in a guide cast into the truck side frames, way more better! Looks like you are having a great time, me all my model RR stuff is in boxes in the attic and few in the garage / Man cave.