In the lineage of New York Central steam locomotive construction, when were cast steel frames used instead of fabricated frames? Would ALCO receive these frames from Adirondack Castings the firm that cast AD on diesel locomotive side frames?
My impression is that locomotive frames (in North America-- elsewhere built-up frames were the norm until the end of steam) gradually came to be assembled from larger and larger castings over the first few decades of the 20th C. (So, for an example from the late 1920s, the PRR M1a had a one-piece casting for the cylinders and the "saddle" the smokebox rested on, the rest of the frame being attached to that. Sometimes, at least, the two side rails of the main frame would be castings.). The final, one-piece, locomotive bed (including cylinders as well as frame) was, I think, introduced at the very end of the 1920s-- I'd have to check, and I'm not sure where to check, but I think the first New York Central J-1 Hudsons were too early, but that the last J-1 (and of course the later J-3 and S) locomotives did have one-piece cast beds.
Adirondack wasn't, I think, involved: these castings were produced by Commonwealth Steel (which, maybe just after the introduction of the one-piece frame, was bought by Alco and Baldwin, and, under the name General Steel Industries, operated as a joint subsidiary of Alco and Baldwin).