The Fairbanks-Morse H-24-66 is a six axle hood unit diesel electric. It was produced between 1953-1957.

History[]
In 1953, Fairbanks-Morse (FM) needed a new engine to make up for the failure of their recent engine, the C-Liners. By April 1953 they had produced a new freight engine capable of 2,400 hp. The H-24-66 or Train Master as it was called was deemed one of the most powerful single diesel engine made. It had a 12 cylinder opposed piston two stroke diesel engine giving it an impressive 112,000 lbs of tractive effort.
The Train Masters ended up being used in a wide variety of traffic. Naturally they were well suited to hauling heavy freights, so the Norfolk & Western and the Virginian put them to work on heavy coal drags through the Blue Ridge mountains. At the opposite end of the spectrum, the Wabash put them to work on hot, high priority freight trains. One of their favorite practices was to sandwich a Train Master between two F7As, giving the crew the better forward visibility of the F7s, with the power of the Train Masters pushing them along. The Central of New Jersey, the Reading, and the Lackawanna tried them out on commuter trains. The Southern Pacific's Train Masters wrapped up their final years of service on commuter trains in San Francisco, where they worked turn and turn about with GP40Ps, SDP40s, and GP9s.
The Illinois Central Railroad famously tested out the Train Masters and placed an order for them, but then turned around and cancelled the order at the last minute.
At one point, the New Haven proposed a variant of the Train Master that could run as a dual mode locomotive, and would've featured third pick-up shoes so that it could pull passenger trains in electrified territory. The plans were cancelled however, mostly due to FM's diminishing reputation at the time and conflicts between GE and FM. New Haven would later to go EMD with the same proposal, and this eventually lead to the creation of the famous EMD FL9.
Unfortunately many railroads thought that the engine had too much power and were deterred from buying. Other problems that plagued the engine included difficulties with maintaining the opposed piston engine, inadequate electrical systems, and larger consumption of cooling water. The Southern Pacific ran into the problem of the engines' air intakes becoming clogged up with sand and dirt that it kicked it up when running through the desert at high speeds.
In the following years the Train Master was outshined by more powerful engines such as the ALCO RSD-7 and later the SD24 and U25C.
One year after the last Train Master was built FM left the locomotive business.
One Train Master survives in operational condition while another is a road slug. The Reading Historical and Technical Society own a Norfolk & Western slug that was rebuilt from a Wabash H24-66.
In the early 1970s, the Norfolk & Western ran a Farewell train for the Train Masters out of Roanoke. The locomotive leading the train was former Virginian Railway H24-66 #173, which was the only N&W Train Master to receive the N&W's all black livery with the large white "NW" on the hood. The 173 was earmarked for preservation, and presumably would've gone to the Virginia Museum of Transportation in Roanoke, but alas, the engine got mixed in the Train Masters that were in line to be converted into slugs.