Under the Whyte notation for the classification of steam locomotives, a 2-10-4 locomotive has two leading wheels, ten driving wheels (in other words, five driven axles), and four trailing wheels. These were referred to as the "Texas" type in most of the United States, the "Colorado" type on the Burlington Route and the "Selkirk" type in Canada.
Other equivalent classifications are:
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 Atchison, Topeka & Santa Fe Railway took delivery of locomotive 3829 from the Baldwin Locomotive Works in 1919, a member of the 3800 class of 2-10-2s fitted with a four wheel trailing truck. Nearly 100 more 3800 class locomotives were delivered after 3829, all with the 2-10-2 wheel arrangement. 3829 was used by the Santa Fe as an experimental locomotive. Photographs exist that show 3829 fitted with at least two different four wheel trailing truck designs through the years. No additional members of the 3800 class have been documented with four wheel trailing trucks and 3829 was scrapped in 1955 with a four wheel trailing truck.
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 and Pacific Railway, after which the type was named.
The early Lima Texas types were low-drivered, 60 through 64 inches (152 through 163 cm) in diameter, 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 inch (175 cm) 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 (PRR) 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 Pennsylvania Railroad urgently needed new, modern freight power. 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. All were sold for scrap as the Pennsylvania Railroad dieselized.
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 in (1.75 m) 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 in (1.88 m) drivers and 310 lbf/in² (2.1 MPa) 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.
|Railroad (quantity; class name)||Road numbers||Builder||Build year|
|Santa Fe (37; Texas)||3829||Baldwin||1919|
|5001 – 5010||Baldwin||1938|
|5011 – 5035||Baldwin||1944|
|Bessemer & Lake Erie (47; Texas)||601||Baldwin||1929|
|602 – 610||Baldwin||1930|
|611 – 620||Baldwin||1936|
|621 – 630||ALCO||1937|
|631 – 635||Baldwin||1941|
|636 – 637||Baldwin||1942|
|638 – 642||Baldwin||1943|
|643 – 647||Baldwin||1944|
|Canadian Pacific (37; Selkirk)||5900 – 5919||MLW||1929|
|8000||CPR Angus Shops||1931|
|5920 – 5929||MLW||1938|
|5930 – 5935||MLW||1949|
|Central Vermont (10; Texas)||700 – 709||ALCO||1928|
|Chesapeake and Ohio Railway (40; Texas)||3000 – 3039||Lima||1930|
|Chicago, Burlington & Quincy (18; Colorado)||6310 – 6321||Baldwin||1927|
|6322 – 6327||Baldwin||1929|
|Chicago Great Western (36; Texas)|| 850 – 864|
880 – 882
|865 – 897||Baldwin||1930|
|883 – 885||Lima||1931|
|Kansas City Southern (10; Texas)||900 – 909||Lima||1937|
|Pennsylvania Railroad (125; Texas)||6450 – 6474||PRR Altoona Shops||1942|
| 6401 – 6434|
6475 – 6500
|PRR Altoona Shops||1943|
| 6435 – 6449|
6150 – 6174
|PRR Altoona Shops||1944|
|Texas & Pacific (70; Texas)||600 – 609||Lima||1925|
|610 – 624||Lima||1927|
|625 – 654||Lima||1928|
|655 – 669||Lima||1929|
18 of the B&LE's 2-10-4 locomotives were sold to the Duluth, Missabe & Iron Range. The DMIR kept the "Texas" class name on these locomotives.
|Santa Fe||5000||Amarillo, TX|
|5011||Museum of Transportation, St. Louis, MO|
|5017||National Railroad Museum, Green Bay, WI|
|5021||California State Railroad Museum, Sacramento, CA|
|5030||Salvador Perez Park, Santa Fe, NM|
|B&LE||643||McKees Rocks, PA|
|CPR||5931||Heritage Park Historical Village, Calgary, AB|
|5935||Canadian Railway Museum, Delson, QC|
|T&P||610||Texas State Railroad, Palestine, TX|
Outside North America, the 2-10-4 was rare. The Central Railway of Brazil, however, ordered seventeen narrow gauge (metre gauge) 2-10-4, ten from Baldwin, which was delivered in 1940, and seven from American Locomotive Company, wich was delivered in 1947. The South African Railways (cape gauge) owned a sole 2-10-4 as Class 21, built in 1937 by North British and scrapped in 1952. A bigger 2-10-4 design, planned as Class 22, was never built.