Editing 2-10-0 (section)

== United States ==
[[File:Pennsylvania Railroad Steam Locomotive -4483 (1).jpg|thumb|Pennsylvania Railroad I1s Locomotive]]
The first Decapods were built for the [[Lehigh Valley Railroad]] in the late-1860s. They proved too rough on the track because of their long coupled [[wheelbase]].<ref>{{cite book
  |last1=Solomon  |first1=Brian
  |title=The Majesty of Big Steam
  |year=2015
  |publisher=[[Voyageur Press]]
  |page=102
}}</ref> No more followed for 19 years, until the [[Northern Pacific Railway]] bought two for use on the switchbacks over [[Stampede Pass]], while the {{convert|2|mi|km|1|adj=on}} tunnel was being built.{{sfnp|Armstrong|1978|pages=74–76}} In low-speed service where high tractive effort was critical, these Decapods were successful. Small numbers of other Decapods were built over the next twenty years, mostly for service in steeply [[grade (slope)|grade]]d mountainous areas where power at low speeds was the requirement. The type did not prove as popular as the successful Consolidation ([[2-8-0]]) type. Among Decapod users was the [[Atchison, Topeka and Santa Fe Railway]]. The engines were [[tandem compound locomotive|tandem compound]]s but their ongoing reversing limitations became the genesis of the [[2-10-2]] wheel arrangement.

[[File:Seaboard 544.jpg|thumb|Seaboard Air Line #544, one of over 200 undelivered [[Class Ye 2-10-0|Russian Decapods]]. It resides at the [[North Carolina Transportation Museum]]. Note the smaller boiler diameter, compared to the I1s above]]
The first boost in the number of Decapods occurred when [[Russian Empire|Imperial Russia]] ordered approximately 1,200 [[Russian locomotive class Ye|Decapods]] from American builders during [[World War I]]. When the [[October Revolution|Bolshevik revolution]] occurred in 1917, 857 had already been delivered,{{sfnp|Drury|1993|page= 176 }} but more than 200 were either awaiting shipment or were in the process of construction.{{sfnp|Drury|1993|page= 176 }} These stranded locomotives were adopted by the [[United States Railroad Administration]] (USRA), the body created by the Government to oversee and control the railroads during the War, converted to American standards, and put to use on American railroads. Small and light-footed, these Russian decapods proved popular with smaller railroads, and many of them remained in service long after the USRA's control of the railroads ceased.<ref>{{cite book |last1=Prince |first1=Richard |title=Seaboard Air Line Railway: Steam Boats, Locomotives, and History |date=2000 |publisher=Indiana University Press |location=United States |isbn=9780253336958 |pages=268 |url=https://books.google.com/books?id=MM2ph3S2V2cC&q=2-10-0%20Detroit%2C%20Toledo%20%26%20Ironton%20Railroad&pg=PA165 |access-date=14 July 2019}}</ref> Many indeed lasted until the end of steam on those railroads.

[[File:544boilergap.jpg|thumb|left|The same [[Class Ye 2-10-0|Russian Decapod]], showing the large gap between the boiler and drivers, typical of locomotives designed for Russia]]
Swengel suggested the 2-10-0 arrangement was 'obsolete' by 1916, when the Pennsylvania Railroad commenced an experiment with a 2-10-0 locomotive at its Juniata plant.{{sfn|Swengel|1967|pages=190-191}} Most 10 coupled engines constructed for U.S. railroads during World War I were of the USRA 2-10-2 arrangement, but the PRR committed to 122 of the 2-10-0s.{{sfn|Swengel|1967}}{{sfn|Staufer|1962|page=65}} Swengel argued this commitment to the 2-10-0, nicknamed "Deks", was controversial even in 1916 and was more so in 1922 when the PRR placed additional orders. The PRR was soon the biggest user of Decapods in the United States. The type was ideally suited to the Pennsy's heavily graded [[Allegheny Mountains]] routes, which required lugging ability according to tractive effort, not speed according to horse power.

The PRR bought 598 2-10-0s including 123 built at its own shops. In one of the largest locomotive orders ever, the rest came from the [[Baldwin Locomotive Works]]. The PRR 2-10-0s weighed {{convert|386100|lb|t|lk=in|abbr=on}} and developed about {{convert|90000|lbf|kN|abbr=on|lk=in|sigfig=4}} of tractive effort{{efn-lr|Maximum cutoff as built was nominally 50% (with small auxiliary ports to aid in starting) so "tractive effort" couldn't be calculated in the usual way. Cutoff on most engines was eventually extended and PRR claimed 96,000 lb for them.}} with an axle loading of over {{convert|70000|lb|t|abbr=on}}. The engines steamed at {{convert|250|psi|MPa|abbr=on|lk=in|sigfig=3}} and had a relatively large superheater. The grate area of about {{convert|70|sqft|abbr=on}} was on the small side, but a mechanical stoker partly compensated for this.{{sfn|Swengel|1967}}

The PRR decapod, class [[PRR I1s|I1s]], was unlike the Russian decapod; it was huge, taking advantage of the PRR's heavy trackage and high [[axle load]]ing, with a fat, free-steaming boiler that earned the type the nickname of 'Hippos' on the PRR. Two giant cylinders (30½ x 32&nbsp;inch) gave the I1s power and their tenders permitted hard and long workings between stops. They were unpopular with the crews, for they were hard riding.{{sfn|Staufer|1962}} The last operations on the PRR were 1957.{{sfn|Staufer|1962}}

A small number of other Decapods were ordered by other railroads; the I-2 Decapods built for the [[Western Maryland Railway]] were the largest ever built, at almost {{convert|420000|lb|t|abbr=on}} weight, and are a notable exception to the rule of thumb for the comfort of the ride on a 2-10-0 wheel arrangement, crews said the engines cruised smoothly up to 50&nbsp;mph without becoming a rough ride. (After the running gear was redesigned by the WM) The WM's I-2 are also noted as the strongest Decapods ever built, at 96,315&nbsp;lbs of tractive effort. (Not to be confused with the 10 Russian Decapods the WM held in their roster, which were standard Russian Decapods aside from heavier steel frames the WM used to replace the original cast iron frames, the new frames also made the WM Russian Decapods 2 inches longer than other Russian Decapods)

Baldwin developed two standard 2-10-0s for railroads with low axle-load requirements.<ref name="Drury-steam351" >King, E.W., Jr. in Drury p. 351</ref>

Thirteen Decapod locomotives survive in the US, including two Baldwin standards, six Russian Decapods and one PRR I1. Two, [[Great Western 90 2-10-0 decapod|Great Western 90]], a Baldwin Decapod at the [[Strasburg Rail Road]], and [[Frisco 1630]], a Russian Decapod at the [[Illinois Railway Museum]], are operational. One Decapod survives as a static exhibit at the North Carolina Transportation Museum in Spencer, North Carolina ([[Seaboard Air Line Railroad|Seaboard Air Line]] 2-10-0 #544).

=== Preserved Decapods in the United States ===
*1621 is on display at the National [[National Museum of Transportation]] - St. Louis, MO
*1625 is on display at the [[Museum of the American Railroad]] - Frisco, TX
*[[St. Louis-San Francisco 1630|1630]] is operated by the Illinois Railway Museum - Union, IL.
*[[Great Western 90|90]] is operated by Strasburg Railroad - Strasburg, PA.
*[[Pennsylvania Railroad I1 class|I1 class]] 4483 is at [[Hamburg, New York]].

===Proposed/Unbuilt (US)===
[[L.D. Porta]] proposed a 2-10-0, triple expansion [[Advanced steam technology|Modern steam locomotive]] as a "second generation" [[freight train|fast-freight]] locomotive for the [[ACE 3000]] project based on his previous works.