I think that they could. It appears based on running times for C&O T-1 hauled trains vs H-8 hauled trains, the terminal to terminal time was about the same. You can conclude that the operation did not favor the higher HP of the Allegheny, and you would be correct. But the time book reprinted in various books about the Allegheny shows that T-1's and H-8's were used interchangeably by the C&O.
The C&O T-1 was one of the greatest steam designs. I am sure you all know that PRR chose the T-1 over the N&W A, and I think I know a few reasons why. Both the C&O engine and the N&W A weighed about the same, 573,000 lb. The C&O engine could be started at "full" cutoff, about 85%. The N&W A was a limited cutoff design with a cutoff of 77% (based on its calculated starting tractive effort). Due to its limited cutoff, its factor of adhesion was 3.79, while the C&O engine was over 4.0, making it inherently less slippery. Designers of simple articulateds fought for maximum weight on the front engine in every design. When PRR tested the "A", they noted the engine's tendency to slip on its test. The five coupled T-1 evidently was a better performer when the "going got tough", at low speeds and with less than perfect adhesion.
UP solved this front engine adhesion issue on their late Challengers by designing a two point suspension (attachment) of the front engine to the frame that was so rigid that the springing was required to make all adjustments for vertical curvature, etc. By the way, the UP late challengers weighed 627,000 lb. vs the N&W "A" class weight of 573,000. And a Challenger could use full cutoff in starting a train. A comparison of "starting tractive effort" is meaningless if the engine can't keep its feet. A Challenger had inherently a heavier front engine with its four wheel lead truck and massive cast pilot. (The N&W "A"'s were also retrofitted with a heavier front pilot casting, perhaps to improve adhesion performance.) I believe that the UP Challenger was a better high speed design than the "A". It had smaller diameter cylinders than the "A", (21" vs 24"). It had a longer stroke (32" vs 30"), and its dimension across the cylinders was lower. (The N&W "A" was 92". I do not have this dimension for the Jabelman Challengers but for the small UP Challengers this dimension was 89" with one inch larger cylinders (22" vs 21"). So the main and side rod mass is closer to the railhead on the UP Challengers, and the four wheel lead truck, in addition to adding weight to the front engine, would have a lower tendency to "nosing".
I read the famous written comparison of the UP challenger and the N&W "A", and the claim that furnace volume was compromised on the Challenger due to the need to locate a part of the direct heating surface over the rear drivers. Furnace volume on both engines is about the same (581 sq ft on the Challenger vs 587 for the "A"). What the pictures do not show is that a UP Challenger was over 4 inches taller than the "A". (16'-2-1/2" vs 15'-10-1/8"). A UP Challenger had 20 ' long tubes while the N&W "A" tube length was 24'-11". My guess is that the Challenger steamed better. It had to, it used lower btu coal!
The PRR tested the J on the Altoona test plant, and minus tender its drawbar HP was in the 5200 range. When PRR tested the "A", the drawbar HP at the rear of the tender was 5200, although an old N&W mechanical dept. man told me that an "A" "could do 5500 drawbar HP all day long". UP rated the Challengers at 5400 maximum cylinder HP using UP coal, which was inferior to that used by N&W. So the drawbar HP of a UP Challenger would have been lower than the N&W "A". The N&W "A"'s performance on coal is often cited as the broad operating range of this engine. I saw and photographed N&W "A" #1222 on a Portsmouth to Williamson coal train in August of 1958, and the "A" had to be given a push by mallet #2059 to get out of the yard. An "A" could do a creditable job on coal as long as it did not have to stop, and I think that was a major reason why these engines were fitted with canteens. The "A" was pluperfect for N&W on east end manifest trains, and the UP Challenger was a great design for manifest service on UP, such that at least six other railroads also adopted this wheel arrangement for similar service.
I am enjoying these postings very much, and mean no offense to either N&W or UP fans.
PS. In my post above, the TE of the DM&IR 2-8-8-4 was 140,000, not 180,000.
