Southern 2716 Stress Test, Part 1: 30 car train

After handling 8 passenger cars and an aux water tender (48 axles total) with ease, I wondered just how much it would pull in total. I was going to use my semi-modern freight cars for the test, but my friends decided I should use their transition-era equipment. We got up to 30 cars (120 axles), which ran for nearly half an hour before the motors decided they'd had enough of my nonsense. There is a bit of extra weight in the smokebox of the locomotive (tungsten cubes) which we're curious how...