Under the Whyte notation for the classification of steam locomotives, 2-6-2 represents the wheel arrangement of two leading wheels, six coupled driving wheels and two trailing wheels. This arrangement is commonly called a Prairie.
Other equivalent classifications are:
- UIC classification: 1C1 (also known as German and Italian classifications)
- French classification: 131
- Turkish classification: 35
- Swiss classification: 3/5
- Russian classification: 1-3-1
- 1 Overview
- 2 Usage
- 3 References
The majority of American 2-6-2s were tender locomotives, but in Europe tank locomotives, described as 2-6-2T, were more common. The first 2-6-2 tender locomotives built for a North American customer, were built by Brooks Locomotive Works in 1900 for the Chicago, Burlington and Quincy Railroad, for use on the Midwestern prairies. The type was thus nicknamed the Prairie in North American practice. This name was often also used for British locomotives with this wheel arrangement.
As with the 2-10-2, the major problem with the 2-6-2 is that these engines have a symmetrical wheel layout, wherein the centre of gravity is almost over the center driving wheel. The reciprocation rods, when working near the center of gravity, induce severe side-to-side nosing, which results in severe instability if unrestrained either by a long wheelbase or by the leading and trailing trucks. Though some engines had the connecting rod aligned onto the third driver, like the Chicago and Great Western of 1903, most examples were powered via the second driver, hence the nosing problems remained with the type.
In Australia, no tender versions of the 2-6-2 operated on any system. However, three classes of 2-6-2T did.
In New South Wales a class of twenty engines, the Class 26, entered service in 1892 and operated until the end of steam. Two are preserved, no. 2606 at the Rail Transport Museum at Thirlmere and no. 2605 at the State Mine Museum in Lithgow.
The Silverton Tramway operated two 2-6-2T tank locomotives from 1891, both of which are preserved in South Australia.
The principal 2-6-2T locomotives which were built for the narrow gauge system of the Victoria Railway (VR), are the now famous "Puffing Billy" engines. Two of these little locomotives arrived from Baldwin Locomotive works in 1898 and a total of seventeen saw service throughout the state on the various narrow gauge timber and gold lines, including the Wangaratta and Walhalla. When the VR determined to close the Upper Ferntree Gully to Gembrook narrow gauge route in the mid-1950s, the Victorian community refused to let the train die. Today, the Puffing Billy Railway has a fleet of saved and modified 2-6-2T engines on active steam roster and is one of Victoria's main tourist attractions.
The most numerous steam locomotive type used in Hungary was the 324 class 2-6-2, built from 1909 onwards, which were still at work in the last days of steam.
The world's first 2-6-2 Prairie type locomotives in New Zealand were a fleet of five tank engines, built by Manning Wardle of Leeds, England and supplied in 1884-85. The private Wellington and Manawatu Railway (WMR) used them for construction, maintenance and local service work, and three were later taken over as the New Zealand Railways (NZR) WH class in 1908.
The second batch of Prairie locomotives was built to an order for the New Zealand Railways Department, with the initial order for ten being let to Nasmyth, Wilson and Company of Manchester, England. This later became the NZR V class which, due to political interference and their being overweight, did not go into traffic until 1890.
New Zealand's third batch of Prairie locomotives was ordered by the WMR in 1884. Their design was almost identical to that of the NZR V class, though they were slightly heavier. They could burn any light fuel, coal or wood as available, and entered service in 1886, soon after the WMR started operating. In 1908, with the purchase of the company by the NZR, they were also awarded the V classification.
In 1885 Baldwin Locomotive Works built New Zealand's fourth batch of Prairie locomotives. These were to become the NZR N class. Six were delivered in 1885 and were of an almost identical design to the previous, but altered to utilise off-the-shelf components supplied by Baldwin. In 1901, four more were built for the NZR, but these were fitted with piston valves actuated by Walschaerts valve gear. In 1891 two of these locomotives had also been built to the same design for the WMR. In 1908, with the purchase of the WMR by NZR, all of these engines were classified as N class.
The NZR’s Addington Workshops joined the list of Prairie suppliers in 1889, producing the first of two NZR W class tank engines. These were followed between 1892 and 1901 with eleven similar NZR WA class tank engines.
Baldwin followed this up with ten similar NZR WB class Prairie tank engines in 1898.
In 1930-31, after nearly thirty years of 4-6-2 Pacific and 4-6-4 Baltic locomotive production, New Zealand dusted off its Prairie plans with the release into service of twenty-four NZR C class 2-6-2 locomotives, designed primarily for shunting and branch line work.
The H. Cegielski Metal Works in Poznań produced one hundred and twenty-two OKl27 class 2-6-2T tank locomotives for the Polish State Railways (PKP) during the period between 1928 and 1933.
Between 1951 and 1954 Fablok built a series of one hundred and sixteen Ol49 class 2-6-2 tender locomotives for the PKP.
Romania designed the 131.000 Class in order to replace the older Hungarian MAV locomotives used on Căile Ferate Române (CFR) secondary lines. A total of 67 locomotives were built at Reşiţa Works between 1939 and 1942, numbered 131.001 to 131.067.
Russia & Soviet Union
In Russia the 2-6-2 was the standard passenger locomotive. They were represented by the pre-revolutionary S (С) (Sormovskij) series and the post-revolutionary Su (Су) series locomotives, the latter of which appeared in 1928. The pre-revolutionary S-series locomotives had the characteristic pointed nose, absent on the Su locomotive. The suffix 'u' means 'usilenny' which translates as strengthened or uprated. Several Su-series locomotives are preserved in working order. However, only one pre-revolutionary S-series locomotive is still around, number S.68. It is preserved at the Saint Petersburg railway museum.
The Su was the standard passenger engine on most mainline routes and it was only on the key trunk lines that the IS class 2-8-4, or later the P36 4-8-4, would be used. Therefore, the majority of passenger miles were hauled by an Su (Су).
Visually the Su was the last true Russian looking design before the American influence of high running boards, bar frames and boxpok wheels became the norm. The Su retained such features as a clerestory skylight in the cab roof and handrails on the outside of the running board. These handrails were a result of the harsh Russian winters, when ice would build up on the running boards, making them highly dangerous. Enginemen had fallen to their death from moving trains and the fitting of promenade deck style handrails was a safety measure ordered by the Tsar in pre-revolutionary times. These features, combined with the high 17 feet (5.182 metres) loading gauge, combined to give the locomotives a uniquely Russian appearance.
The first locomotives to enter service on the new 3 feet 6 inches Cape gauge mainline of the Cape Government Railways were 2-6-2 side-tank engines that were delivered between 1875 and 1879. Four-wheeled tenders were also acquired and the locomotives could be operated in either a tank or tank-and-tender engine configuration, as circumstances demanded. These locomotives were later designated the Cape 2nd Class.:23–25
In 1901 the Zululand Railway Company, contracted for the construction of the Natal North Coast line from Verulam to the Tugela River, acquired one 2-6-2 side-tank locomotive as construction engine from Baldwin Locomotive Works. Upon completion of the line in 1903, the locomotive was taken onto the roster of the Natal Government Railways and was designated Class I.:90–91
The first four Prairie locomotives built for the Cape Government Railways (CGR) by Neilson, Reid and Company, later the Class 6Z on the South African Railways (SAR), were placed in service in 1901, but they displayed the Prairie’s tendency to be unsteady at speed. They were therefore soon modified to a 2-6-4 Adriatic wheel arrangement.:52–54, 56
With an improved design of bissel truck, two more CGR locomotives that were ordered from Kitson and Company in 1903 were once again built with a 2-6-2 Prairie wheel arrangement. These two locomotives did not display the tendency to sway at speed and therefore retained their 2-6-2 wheel arrangement. In 1912, when they were assimilated into the SAR, they were renumbered and reclassified to Class 6Y.:52–54, 56:45
Switzerland had four classes of 2-6-2T tank locomotives.
- The first was the Bodensee–Toggenburg-Bahn (BT) class Eb 3/5 (speed limit 75 km/h), of which nine were built in 1910 by Maffei, numbered 1 to 9. Seven were scrapped, number 6 stands a long time as a monument in Degersheim and now the Club del San Gottardo in Mendrisio gets them in working order. Number 9, the only one with red trim, was preserved by the Dampf-Loki-Club Herisau in Bauma. 
- The second was the Swiss Federal Railways (SBB) class Eb 3/5 (speed limit 75 km/h), of which 34 were built from 1911 to 1916 by Swiss Locomotive and Machine Works (SLM), numbered 5801 to 5834. 31 were scrapped, number 5810 was preserved by the Verein Dampfbahn Bern in Konolfingen,  number 5811 stands as a monument in Baden and now the Dampfgruppe Zürich in Brugg gets them in working order,  while number 5819 was preserved by the SBB Historic in Brugg. 
- The third was the class Ec 3/5 (speed limit 65 km/h) of the Lake Thun railway (TSB) and other railways of the Bern–Lötschberg–Simplon railway group (BLS). Six engines were built from 1905 to 1907 by the SLM, numbered 41 to 46. After electrification the tracks in 1921/22 all six were sold to the Austrian Federal Railways and renumbered as class 130.
- The fourth was the Mittelthurgau-Bahn (MThB) class Ec 3/5 (speed limit 60 km/h), of which four were built in 1912 by SLM, numbered 1 to 4. Three were scrapped and number 3 was preserved by the Verein Historische Mittel-Thurgau-Bahn in Romanshorn and pulls occasionally the so-called Mostindien-Express. 
In 1997 the MThB number 3 was used as the prototype for the locomotive in the animated 20th Century Fox motion picture "Anastasia", where it was given the appearance of a Soviet Union continental locomotive numbered 2747.
The first UK 2-6-2 tender locomotive was the unsuccessful prototype Midland Railway Paget locomotive of 1908. Thereafter the wheel arrangement was rare on tender locomotives, with the exception of two classes on the London and North Eastern Railway. These were the Class V2 and Class V4 mixed traffic locomotives which totalled 186 locomotives between them.
In contrast, 2-6-2T tank locomotives were very widely used on suburban passenger services, particularly by the Great Western Railway (GWR), which built four main classes between 1903 and 1947. (See GWR 2-6-2T).
The 2-6-2T layout was popular for large narrow gauge engines, but the design was modified to allow the use of a firebox much wider than the track gauge. A standard gauge 2-6-2T normally has inside frames and the firebox is placed between the second and third coupled axles. A narrow gauge one, on the other hand, has outside frames and the firebox is placed behind the third coupled axle and clear of the wheels. To minimise the rear overhang, the fuel is therefore carried in side-bunkers alongside the firebox, instead of in a rear bunker.
United States of America
The 2 ft (610 mm) gauge Sandy River and Rangeley Lakes Railroad in Franklin County, Maine, was a major narrow gauge user.
In the United States the type evolved from the 2-6-0 configuration. The Atchison, Topeka and Santa Fe Railway (AT&SF) became a pioneer of the type in the U.S. in 1901 and one of the largest fleet users of the type. Problems the road encountered with the type included steam leakage in the compound cylinder plumbing and instability at speed. The former problem was solved by converting them to simple, two-cylinder locomotives; the latter problem required new Pacific types with four-wheeled guide trucks. The Prairie types were rebuilt with smaller drivers for slightly slower fast freight service. These engines tended to enjoy very long service lives, and outlasted many a newer, more efficient steam locomotive on the Santa Fe and elsewhere. This was due to their modest weight, good speed and ability to operate well in reverse, which made them valuable for branch line operations.
In 1902 the AT&SF had a 2-6-2 with a high, at the time, boiler pressure of 220 pounds per square inch (1,517 kilopascals), mounted on a large 41 square feet (3.8 square metres) fire grate.
More than a thousand examples of the 2-6-2 wheel arrangement existed in the United States. Of these, one hundred were high-wheeled engines with larger than 69 inches (1.753 metres) drivers. The Lake Shore & Michigan Southern operated locomotives with 80 inches (2.032 metres) drivers, but this did not overcome their inherent instability. They were never as successful in passenger service in the U.S. as they were in other nations.
- Swengel, p. 79.
- 131.000 Class Locomotive at railwayfan.ro (Romanian)
- Russian Steam Locomotives, LeFleming/Price
- Locomotives of Russia 1845 - 1955, V.A.Rakov
- Holland, D.F. (1971). Steam Locomotives of the South African Railways, Volume 1: 1859-1910 (1st ed.). Newton Abbott, Devon: David & Charles. ISBN 978-0-7153-5382-0.
- Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. ISBN 0869772112.
- Boddy et al. 1984, p. 69
- Swengel, p. 78.
- Swengel, p. 80.
- Boddy, M. G.; Brown, W. A.; Hennigan, W.; Hoole, Ken; Neve, E.; Yeadon, W. B. (September 1984). Fry, E. V., ed. Locomotives of the L.N.E.R., Part 6C: Tender Engines—Classes Q1 to Y10. Kenilworth: RCTS. ISBN 0-901115-55-X.
- Oberg, Leon. Railways of Australia, Reed, Sydney, 1975. (plus subsequent editions)
- Swengel, F.M. The American Steam Locomotive, Vol. 1, The Evolution of the Steam Locomotive, MidWest Rail Publications, Davenport, 1967.