The 4-8-4 Northern was arguably the apex of the American steam passenger locomotive, the ultimate combination of power and speed. No wonder that an inordinate number of the engines most renowned among railfans and modelers are 4-8-4s: think Southern Pacific Daylight, Norfolk and Western J, Union Pacific FEF-3, New York Central Niagara, or C&O Greenbrier, for example.
The wheel arrangement had its origin in late 1926 on the Northern Pacific Railway, giving it naming rights. Just months later, Baldwin delivered the Santa Fe's initial 4-8-4s, answering the need for bigger power to keep up with heavier trains and more demanding schedules. Compared with the road's existing 4-8-2 Mountain types, the Northerns could pull 33% more tonnage while using 19% less coal. At the head of the Chief, the Scout, the Grand Canyon Limited and the California Limited, the Santa Fe's 4-8-4s ruled the rugged terrain from Kansas City to Los Angeles, leaving the plains east of Kansas City to lesser power like 4-6-2s and 4-6-4s. Between K.C. and L.A., the Santa Fe's Northerns held down the world's longest scheduled steam run without a change of locomotive, 1,760 miles over Raton Pass with its 3% grade, or 1,790 miles via Amarillo. Along the way, a single engine experienced 12 crew changes, 16 water stops, and almost as many fuel stops. Officially rated at 90 mph, the Northerns were known to frequently hit 100.
The 2900 Class was the final expression of the Santa Fe 4-8-4, delivered by Baldwin Locomotive Works in 1943-44. Like most of their older siblings, the 2900s burned oil and rode on 80" Boxpok drivers with Timken roller bearings. Due to wartime rationing of lightweight, high-strength alloys, heavier metals were used in some areas, making the 2900s the heaviest Northerns ever built. They could pull 26 passenger cars on level track and 15 up a 2% grade. In freight service during the war and later, after diesels took over as passenger power, they could hustle 100 or more cars over level track. An unusual feature of the engines was an extendable smokestack, which could be raised when traveling over wide-open spaces to direct smoke away from the cab.