I was recently looking at current pictures of CDOT/MN and Maine Eastern FL9ms and I noticed the first truck had 4 wheels and the back had 6. Were they built with this arrangement or did it get modified in the rebuilds? Was it a B-A1A or a B-C arangement? What is the purpose of this arrangement? Does it have to do with the thrid rail pickup?
The B-A1A arrangement was to carry the water tank for Steam generator for heat.
There was a 600 gallon tank inside the car body between the Steam generaor and the main engine.
The big watertank pushed the Axle load beyond what Park avenue viaduct could handle so the engine was ordered with the 5 axle arrangement.
It made for quite a rough ride however as the engine did not have equal front and rear suspention.