Sort of bumping the AC4400 dynamic brake issue, but expanding it a little bit. Something is off with the AC4400 and braking altogether. I ran a little experiment in scenario planner down SPG, once with AC400s and again with the dash 8: For my tests, I aimed to be between 18-22 mph when cresting the grade before entering the tunnel. At 23mph, the DB was moved to setup and applied around 25mph. (Still within optimal DB range) AC4400 - 4400 hp AC traction locomotive, ~180,000lbs starting tractive effort C40-8W - 4000 hp DC traction locomotive, ~106,000lbs starting tractive effort First, 50 loaded coal wagons headed by 2 AC4400s (8800 hp total) DB8 was needed almost instantly. Once that became ineffective, I applied a minimum reduction, which did absolutely nothing. I increased to a 50% service application where eventually the train started to slow down. I stopped this test here. Second, 50 loaded coal wagons headed by 4 C40-8W, but to make this test more comparable, I cut the two trailing dash 8s out (8000 hp total) Same process to start as the AC4400, moved to DB8. When that became ineffective, I went to a minimum reduction of air, and from there I was able to find a happy medium between keeping the air brakes on min reduction and adjusting the DB as needed. So the Dash8 consist, 8000 total hp & DC traction motors = you can follow typical descending grades procedure The AC4400, 8800 total hp & AC traction = max dynamics & lots of air to just stop forward acceleration So unless I'm missing something, the AC4000 is massively under-powered when braking.
