Some of the PRR J-1's had valuable improvements compared with the original C&O 2-10-4 of 1930. One major was a one piece cast GSC engine bed. The PRR J-1's were regarded by the PRR as a "drag" engine, however. A PRR test report on the PRR 4-4-6-4 Q-2 compares it with the standard PRR "high speed freight locomotive", the PRR M-1 4-8-2! Go Figure.
The PRR J-1's had about the same drawbar HP performance as the N&W A class, but the "A" was faster. Both engines weighed 573,000 lb, and the PRR due to its heavier axle loadings could do with five driving wheel sets and two cylinders what N&W required six driving axles and four cylinders to do. (The N&W A had two weaknesses for "mountain work". One was a low factor of adhesion and the second was limited cutoff.) The limited cutoff increased maximum horsepower, great for manifest freight, but handicapped the engine at low speeds. After all, the N&W had the Y-6 for mountain work! The speed limit for general freight on the PRR was 40 mph, and most mineral trains ran even slower, so the J-1 design was better for the PRR.
