Under the Whyte notation for the classification of steam locomotives by wheel arrangement, represents a configuration of a four-wheeled leading bogie, four powered and coupled driving wheels, and two trailing wheels supporting part of the weight of the boiler and firebox. This allows a larger firebox and boiler than the configuration.

This wheel arrangement is commonly known as the Atlantic type, although it is also sometimes called a Milwaukee or 4-4-2 Milwaukee, after the Milwaukee Road, which employed it in high speed passenger service.Trains Magazine, Special Issue, Steam's Lost Empire, https://www.trains.com/archives/special-issues/steams-lost-empire-i/, on the milwaukee road, "A Steam Performance of World Stature"

Overview While the wheel arrangement and type name Atlantic would come to fame in the fast passenger service competition between railroads in the United States by mid-1895, the tank locomotive version of the Atlantic type first made its appearance in the United Kingdom in 1880, when William Adams designed the 1 Class T of the London, Tilbury and Southend Railway (LT&SR).

The is the tank locomotive equivalent of a 4-4-0 American type tender locomotive, but with the frame extended to allow for a fuel bunker behind the cab. This necessitated the addition of a trailing truck to support the additional weight at the rear end of the locomotive. As such, the tank version of the wheel arrangement appeared earlier than the tender version.

The tender version of the originated in the United States of America, evolving from the less stable 2-4-2 Columbia type wheel arrangement, and was built especially for mainline passenger express services. One advantage of the type over its predecessor 4-4-0 American type was that the trailing wheels allowed a larger and deeper firebox to be placed behind the driving wheels.Ellis, Hamilton. (1949). Some Classic Locomotives. London: George Allen & Unwin. .

The first use of the wheel arrangement for a tender locomotive was under an experimental double-firebox locomotive, built to the design of George Strong at the Hinkley Locomotive Works in 1888. The locomotive was not successful and was scrapped soon afterwards. The wheel arrangement was named after the second North American tender locomotive class, built by the Baldwin Locomotive Works in 1894 for use on the Atlantic Coast Line of the Philadelphia and Reading Railway.Poultney, E.C. (1952). British Express Locomotive Development, 1896-1948. London: George Allen & Unwin. p. 40.

Baldwin's ideas on 4-4-2 tender locomotives were soon copied in the United Kingdom, initially by Henry Ivatt of the Great Northern Railway (GNR) with his GNR Class C1 Klondyke Atlantic of 1898. These were quickly followed by John Aspinall's Class 7, known as the High-Flyer, for the Lancashire and Yorkshire Railway (L&YR).

Usage

Austria-Hungary

The first European Atlantic locomotive type was the Austro-Hungarian IId class of the Kaiser Ferdinands-Nordbahn (KFNB). It was built from 1895 and later became the 308 class on the Imperial Royal State Railways (kaiserlich und königlich Staatsbahnen, kkStB).

It was followed from 1901 by the XVIb class of the Austrian Northwestern Railway (Österreichische Nordwestbahn, ÖNWB) that later became the kkStB class 208, and then by the kkStB 108 class. They were not numerous, though. All three classes together numbered a little more than one hundred locomotives.Jindřich Bek, Zdenek Bek. (1999). Parní Lokomotivy ČSD . Prague. pp. 41, 45-48. (in Czech)

Apart from the Austrian locomotives, the Hungarian State Railways (Magyar Államvasutak or MÁV) also operated some Atlantic classes.

Belgium

In 1939, the National Railway Company of Belgium (NMBS/SNCB) introduced six Class 12 streamlined Atlantic locomotives on the fast lightweight boat trains that ran on the line between Brussels and Ostend. Designed by Raoul Notesse to be capable of speeds of and based on the successful Canadian Pacific Railway 4-4-4 Jubilee type semi-streamlined locomotives, but incorporating the ideas on streamlining of André Huet, they were built by John Cockerill at Seraing. They were fully streamlined, except for openings to provide access to the valve gear and motion, and had inside cylinders with outside valve gear to reduce oscillation at speed. The class remained in service until 1962.

Germany

The Atlantic, known in Germany as the 2'B1' wheel arrangement, enjoyed some short-lived popularity in the German states. Between 1902 and 1906, the class of the Prussian state railways was built to two competing designs, 159 locomotives to the design of August von Borries and 79 locomotives to that of Alfred de Glehn. Between 1908 and 1910, Hanomag built 99 Prussian S 9 locomotives. All were four-cylinder compound engines working on saturated steam. The Prussian Atlantics were withdrawn shortly after the First World War and some were given to France, Belgium and Poland.Herbert Rauter, Günther Scheingraber (1991), Preußen-Report. Band 2: Die Schnellzuglokomotiven der Gattung S 1 - S 11. Hermann Merker Verlag, pp. 60–80. (in German)

Atlantics were also adopted in some other German states. Twelve Pfalz P3.1 class locomotives were built for the Palatinate Railway (Pfalzbahn) from 1898. In addition, eleven Pfalz P4 class locomotives were built from 1905. Fifteen Saxon X V class locomotives were built for the Royal Saxon State Railways from 1902. Eighteen Baden IId class locomotives were built for the Grand Duchy of Baden State Railways from 1902. In 1900, the Royal Bavarian State Railways imported two 4-4-2 locomotives from Baldwin Locomotive Works in the United States of America and classified them Bavarian S 2/5. Ten more locomotives were built by Maffei in 1904.

India In India, the broad gauge E class was rebuilt in the 1940s and survived into the 1970s.

Japan

In 1895 the then private gauge Nippon Tetsudo (Japan Ry) sought, without success, to use low grade coal from the online Iwaki and Iryana mines in conventional narrow firebox loomotives. At that time the Baldwin Locomotive Works, in the United States of America, offered and guaranteed to build locomotives to burn successfully any fuel sent to them. For this case, Baldwin employed a wide firebox placed behind the drivers and over a trailing truck, building 24 4-4-2s and 20 2-8-2s to a single order in 1897 - recording that "They gave excellent satisfaction, and are wonderfully free steamers."BLW Record of Recent Construction 27, Broad Firebox Locomotives, 1901, p11-15, online at HathiTrust Following nationalization, the Atlantics became Japanese Railways 6600 Class. Six more locomotives, built to the same design, were built for the Cape Government Railways in South Africa immediately following the completion of the Japanese order.

Mozambique By the 1980s, the last Atlantics at work in the world were a few examples in Mozambique. These survived reported retirements to operate into the beginning of the 21st century, becoming some of the last working steam in the country. Exceptionally, they had outlasted much larger and newer power, including Garratt locomotives.

Philippines

The Manila Railway (ancestor to the Philippine National Railways) purchased five 100-class locomotives from the North British Locomotive Company in 1906. These were the first tender locomotives in Philippine service. In 1949, 7 American-built 4-8-2s were also numbered as the 100 class, presuming that the locomotives have been retired after World War II.

South Africa

In 1897, additional locomotives were urgently required by the Cape Government Railways (CGR) for the section south of Kimberley, at a time when locomotive production in England was being disrupted by strikes, while simultaneously the steamship companies had suddenly doubled all their freight rates to the Cape of Good Hope. As a result, six locomotives were ordered from Baldwin Locomotive Works. These were built in addition to a just fulfilled order for 24 Atlantics, designed and built for the then private gauge Nippon Tetsudo, later nationalized into the Japanese Railways.

The locomotives were completed within sixty days of receipt of the order and, to circumvent the exorbitant freight charges of the steamship lines, were shipped to the Cape by sailing ship, with the result that the steamship companies promptly reverted to their old rates. Nicknamed the Hatracks, the locomotives were designated 4th Class on the CGR. When they came onto South African Railways (SAR) stock in 1912, they were considered obsolete and designated Class 04. They remained in SAR service until 1931.

United Kingdom

Tank locomotives The T Atlantic was introduced into the United Kingdom in 1880 by William Adams, who designed the LT&SR 1 Class on behalf of Thomas Whitelegg of the London, Tilbury and Southend Railway (LT&SR). This was the first use of this wheel arrangement in the world. It was intended for heavy suburban trains around London and 36 locomotives were built by Sharp, Stewart and Company and Nasmyth, Wilson and Company between 1880 and 1892. Adams later developed the type into his successful suburban 415 class for the London and South Western Railway.

The LT&SR continued to build tank locomotives after 1897, with the Class 37, Class 51 and Class 79. Henry Ivatt of the Great Northern Railway (GNR) also built sixty Class C2 tank locomotives between 1898 and 1907, for use on local and commuter trains in Yorkshire and North London.

During the first decade of the twentieth century, the Atlantic tank locomotive became very popular in the United Kingdom. The Great Central Railway’s Class 9K and Class 9L were built between 1903 and 1907. They later became the LNER classes C13 and C14. The Great Western Railway’s 2221 Class was built between 1905 and 1912. The London and North Western Railway’s Precursor Tank Class was built between 1906 and 1909. Four classes were introduced by the London, Brighton and South Coast Railway, the I1 class, I2 class, I3 class and I4 class.

Tender locomotives

Following Henry Ivatt’s GNR Class C1 Klondyke Atlantic of 1898 and John Aspinall's L&YR Class 7 High-Flyer, of which forty were built between 1899 and 1902, a lot of interest was shown in the Atlantic type by British railways during the first decade of the twentieth century, especially for express passenger train service. Between 1902 and 1908, Ivatt built eighty larger boilered versions of his GNR Class C1, which were known as the Large Boiler Class C1. These remained in service until the early 1950s.

In 1903, for use in comparative trials against his own designs, George Jackson Churchward of the Great Western Railway (GWR) purchased three French De Glehn compound s, beginning with the GWR no. 102 La France and followed by two larger locomotives in 1905. Fourteen members of his two-cylinder 2900 Saint class locomotives were subsequently either built or rebuilt with this wheel arrangement, including one four-cylinder GWR 4000 Star class, no. 40 North Star. All of these were later rebuilt to a 4-6-0 wheel arrangement.

Wilson Worsdell of the North Eastern Railway (NER) designed his classes V and 4CC between 1903 and 1906, while his successor on the NER, Vincent Raven, introduced his V/09 and NER Class Z classes between 1910 and 1917. By 1918, however, the type had been largely superseded by the 4-6-0 type in the United Kingdom.

The London, Brighton and South Coast Railway (LB&SCR) H1 class, introduced by D. E. Marsh in 1905 and 1906, was copied from the plans of the Ivatt C1 class, with minimal alterations. In 1911, L.B. Billinton was granted authority to construct a further six examples incorporating Schmidt superheaters, which became the LB&SCR H2 class.