This locomotive type can either be viewed as a 2-10-2 "Santa Fe" type with an enlarged firebox requiring the larger trailing truck, or a longer 2-8-4 "Berkshire" type requiring extra driving wheels to fit within axle-loading limits. Indeed, examples of both of those evolutionary progressions can be found.
The first 2-10-4 was indeed a 2-10-2 "Santa Fe" type with a bigger trailing truck; in 1919 the Atchison, Topeka & Santa Fe Railroad built one of its 3800 class 2-10-2 locomotives, #3829, with a 4-wheel trailing truck to see if there were any advantages. However, no attempt to expand the locomotive to take advantage of the larger truck was done, and the locomotive remained a one-off, although it carried the 4-wheel truck until its demise in 1955.
The 2-10-4 type was revived in 1925 by the Lima Locomotive Works, and this time it was an expansion of the 2-8-4 "Berkshire" type that Lima had pioneered. The four-wheel trailing truck allowed a much larger firebox and thus a greater ability to generate heat (and thus steam) - the Superpower design, as Lima's marketing department called it, meant for a locomotive that could develop great power at speed and not run out of steam-generating ability. A version of the Berkshire with ten driving wheels instead of eight was an obvious development, and the first delivered were to the Texas & Pacific Railway, after which the type was named.
The early Lima Texas types were low-drivered, 60" through 64", which did not give enough space to fully counterweight the extremely heavy and sturdy side rods and main rods required for such a powerful locomotive's piston thrusts. That changed with the Chesapeake & Ohio Railroad in 1930, who stretched an Erie Railroad high-drivered Berkshire type to produce 40 of the T-1, a Texas with 69" drivers that was both powerful and fast, fast enough for the new higher-speed freight services the railroads were introducing. All subsequent Texas types were of this higher-drivered sort.
The Pennsylvania Railroad ordered few new locomotives after 1930; electrification both ate up the railroad's resources and provided a supply of excess steam locomotives, soaking up any requirement for new power. It was not until World War II had begun that the PRR's locomotive fleet began to look inadequate. The Pennsy needed new, modern freight power in a hurry. The War Production Board prohibited working on a new design, and in any case there was not enough time to trial a prototype. Instead, the PRR cast around for other railroads' designs it might modify for PRR use, settling on the C&O T-1. Some modifications were made for the PRR; the PRR drop-coupler, sheet steel pilot, a PRR style cab, a large PRR tender, a Keystone numberplate up front, and other modifications. It still betrayed its foreign heritage by lacking the PRR trademark Belpaire firebox and by having a booster engine on the trailing truck. 125 locomotives were built between 1942 and 1944, the largest fleet of Texas type locomotives in existence.
The Santa Fe, who had originated the 2-10-4 type, tried again in 1930 with #5000, nicknamed "Madam Queen". This locomotive was very similar to the C&O T-1 described above, with the same 69" drivers. It proved the viability of the type on the Santa Fe, but the Great Depression shelved plans to acquire more. In 1938, with the railroad's fortunes improving, the Santa Fe did acquire ten locomotives; these were ordered with 74" drivers and 310 psi boiler pressure, making the Santa Fe 2-10-4s the fastest and most modern of all. Of the original order of ten, five were oil-burning and five coal-burning; when the Santa Fe ordered 25 more for 1944 delivery, all were delivered equipped to burn oil.Santa Fe prototype
Lima revives the 2-10-4
The C&O perfects the type
The Pennsy's "War Babies"
Santa Fe's express locomotives
| Railroad | Quantity | Name |
|---|---|---|
| Santa Fe | 37 Baldwin | Texas |
| Bessemer & Lake Erie | 37 Baldwin, 10 ALCO | Texas |
| Canadian Pacific | 36 MLW, 1 CPR | Selkirk |
| Central Vermont | 10 ALCO | Texas |
| Chesapeake & Ohio Railroad | 40 Lima | Texas |
| Chicago, Burlington & Quincy | 18 Baldwin | Colorado |
| Chicago Great Western | 15 Baldwin, 21 Lima | Texas |
| Duluth, Missabe & Iron Range | 18 from B&LE | Texas |
| Kansas City Southern | 10 Lima | Texas |
| Pennsylvania Railroad | 125 PRR | Texas |
| Texas & Pacific | 70 Lima | Texas |
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