Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of four leading wheels, eight powered and coupled driving wheels and two trailing wheels. This type of steam locomotive is commonly known as the Mountain type, though the New York Central Railroad used the name Mohawk for their 4-8-2s.
Overview The Colony of Natal in South Africa and New Zealand were innovators of the Mountain wheel arrangement. The Natal Government Railways (NGR) placed in service the first tank engines with the 4-8-2 arrangement, and the NGR was also first to modify tender locomotives to use a 4-8-2 wheel arrangement. The New Zealand Railways Department (NZR) introduced the first tender locomotives designed and built as 4-8-2.
In 1888, the Natal Government Railways placed the first five of its eventual one hundred Class D tank locomotives in service. The locomotive was designed by William Milne, the locomotive superintendent of the NGR from 1877 to 1896, and was built by Dübs & Company. This was the first known use of the wheel arrangement.
In 1906, six NGR Class B Mastodon locomotives, designed by D.A. Hendrie, NGR Locomotive Superintendent from 1903 to 1910, were modified to a wheel arrangement by having trailing bissel trucks added below their cabs to improve their stability when hauling fast passenger trains. These altered Class B locomotives were the first tender locomotives in the world.
The first locomotive to be designed and built as a tender locomotive was New Zealand's X class, designed by Alfred Beattie and built by NZR's Addington Workshops in 1908. It was designed to haul heavy freight trains on the mountainous central section of the North Island Main Trunk. Some believed this was the source of the "Mountain" name of the type, although it is also possible that the name was originated by the Chesapeake & Ohio Railway in the United States, who named the type after the Allegheny Mountains. The X class was, however, not a typical Mountain type, since its trailing truck served to spread the axle load rather than to allow a larger and wider firebox. The trailing wheels were positioned well behind a narrow firebox, which itself sat above the coupled wheels, necessitating the same design compromise between coupled wheel diameter and grate size as on a Consolidation or 4-8-0 Twelve wheeler. A more common design was a progression of the classic 4-6-2 Pacific layout, which featured a wide firebox positioned above the trailing truck and behind the coupled wheels, allowing for a wide and deep firebox as well as large coupled wheels.
The NGR in 1909 placed in service the first example of the more common Mountain design, when it commissioned five Class Hendrie D tender locomotives. It was designed by Hendrie to handle coal traffic on the upper Natal mainline and, while it was based on the Class Hendrie B , it had the firebox positioned to the rear of the coupled wheels to make a larger grate and ashpan possible. To accomplish this, the plate frame was equipped with a cast bridle at the rear to accommodate the improved firebox design, and the load also necessitated the addition of a trailing truck. Five locomotives were built by the North British Locomotive Company and delivered in 1909. The type went on to become the most widely used steam locomotive wheel arrangement in South Africa, with altogether thirty classes of both tank and tender versions eventually seeing service on the South African Railways.
Usage Angola
In 1951, six locomotives were built by North British Locomotive Company to the design of the South African Class 19D for the Angolan Caminho de Ferro de Benguela (CFB or Benguela railway) as their 11th Class.North British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser
Australia Unlike some other countries which utilised the design for heavy passenger duties, the Australian was more typically used as a heavy goods locomotive with small coupled wheels and a very large firebox.
The first in Australia was the gauge Q class of the Tasmanian Government Railways. Nineteen were built in batches between 1922 and 1945 by Perry Engineering in South Australia, Walkers Limited of Maryborough, Queensland and Clyde Engineering of New South Wales. Until 1950, the class handled the majority of mainline goods trains around the state.Tasmanian Government Railways Q5 Statically DisplayedExhibit Q5 Tasmanian Transport Museum
Armstrong Whitworth built ten 500 class 4-8-2 locomotives for the South Australian Railways in 1926. They were the most powerful locomotives in Australia at the time and the heaviest non-articulated locomotives yet built in the United Kingdom. In 1929, they were modified to 500B class 4-8-4 Northern locomotives.
The three-cylinder D57 class locomotive of the New South Wales Government Railways (NSWGR) was one of the largest and most powerful locomotives ever built in Australia. Twenty-five were built by Clyde Engineering from 1929. With their large grates and tractive effort, they were put to good use on the steep, 1 in 33 (3%) and 1 in 40 (2½%) gradients leading out of Sydney on the New South Wales mainlines.
The D57 design was developed further in 1950 with the smaller cylindered D58 class, of which thirteen were built at the Eveleigh and Cardiff Locomotive Workshops of the NSWGR. This class proved to be less successful, suffering from reliability problems attributed to the rack and pinion valve gear that was used for the third cylinder instead of the Gresley-Holcroft valve gear that was used on the D57 class.New South Wales Government Railways Australian Steam
The Western Australian Government Railways (WAGR) introduced two classes of 4-8-2 locomotives for freight haulage on the state's network. The first was the S class, of which ten were built at the WAGR Midland Railway Workshops from 1943, with the locomotives named after West Australian mountains.New Mountain Type Locos Building for West Australian Railways Truck & Bus Transportation April 1940 page 24Mixed-Traffic 4-8-2 Locomotives Railway Gazette 7 January 1944 page 16 The second was the W class, of which 64 were built by Beyer, Peacock & Company in 1951 and 1952.Delivery of Class W 4-8-2s Railway Gazette 1 June 1951 page 609 The 4-8-2 layout allowed for the weight of these relatively powerful locomotives to be spread over a number of axles, resulting in the W class having a maximum axle load of less than 10 tons. It also enabled the incorporation of a wide firebox for burning poor-quality coal.
In 1951, the Tasmanian Government Railways purchased a modern 4-8-2 locomotive, the H class. Eight locomotives were built by Vulcan Foundry for freight train working.Tasmanian Government Railways Australian SteamTasmanian 4-8-2 Locomotives Locomotive, Railway Carriage & Wagon Review issue 709 September 1951 page 139
Bulgaria In 1941, the Bulgarian State Railways (BDZ) placed an order with Henschel & Son in Germany for fifty BDZ class 03 express passenger locomotives. They were of the type (2-4-1 axle arrangement, simple steam expansion, superheating, three-cylinder, fast train service) and were designed to be capable of hauling heavy passenger trains over the often severe profiles of the Bulgarian mainlines, with gradients of up to 2.8%.
The first two locomotives were delivered by the end of 1941. During trials, it proved that the specifications of the BDZ designing engineers were correct and that they had successfully overcome the shortcomings of insufficient power and some construction problems that had been experienced with the BDZ Mikado class 01 and class 02 locomotives. Mass production began the following year, but was interrupted by war restrictions introduced by the German authorities and delivery was halted before the full order was filled. Only ten more locomotives were built and delivered at the end of 1942 and early 1943, and the total number of the BDZ class 03 remained at twelve locomotives, numbered 03.01 to 03.12.
After 1958, these locomotives were gradually converted to mixed fuel oil and coal firing, which resulted in improved steaming ability and better performance, particularly on mountainous lines. During their 35 years of service, they exhibited excellent performance with only minor problems such as oval wear on the leading axle's inside crank. After factory repair, one of these locomotives, no. 03.12, was preserved in the depot at Gorna Oryahovitsa and returned to operation for tourist trains.
Canada The Angus Shops of Canadian Pacific (CP) built a pair of locomotives in 1914. While they were not replicated, CP kept them in service for thirty years. CP reverted to 4-6-2 Pacific locomotives before moving on to the 4-6-4 Hudson.Drury pp. 66, 70
Canadian National operated eighty U-1 class locomotives in passenger service, built by Montreal Locomotive Works in 1944. The last twenty, designated the U-1-f class, were delivered with semi-streamlined conical smokebox covers that earned them the nickname of Bullet Nose Bettys.
Czechoslovakia The Czechoslovak State Railways (ČSD) introduced the 498.0 class express passenger locomotive in 1938 following successful trials in the Tatra Mountains comparing it to an alternative 2-8-4 Berkshire prototype. In 1954, the design was developed further into the 498.1 class. These technically sophisticated locomotives were reputedly capable of 11% thermal efficiency.
The ČSD also built a lighter and more numerous 475 class locomotive.
France In France, the Mountain, known as the 241 type based on its axle arrangement, began to be used on the more undulating routes as increasingly heavy loads, brought about by the introduction of all-steel passenger cars after 1918, began to overtax the hill-climbing capabilities of the existing Pacific and the speed capabilities of Mikado locomotives. Altogether 275 locomotives were built for French service. The Chemins de fer de l'Est (Est) took delivery of a prototype four-cylinder compound locomotive from its own Épernay shops in 1925. This was the first Mountain type to be built for commercial service within France. The Est subsequently ordered forty production locomotives in 1930, based on the prototype design but with improvements. Delivery took place over the following three years. One of these, 241.004, ended up in Germany during World War II and served in the East German Deutsche Reichsbahn until 1955 as , the only Mountain in German service. Between 1930 and 1932, the Chemins de Fer de l'État (État) obtained 49 locomotives built to the design of the Est. Under SNCF management after 1938, these locomotives were transferred to the Est region and served there for the rest of their service lives. The Chemins de fer de Paris à Lyon et à la Méditerranée (PLM) introduced 145 bullet-nosed Class 241A compound Mountain types in 1925 to increase train speeds over the Seuil de Bourgogne incline. This four-cylinder compound locomotive was unusual in having short connecting rods for the outside high-pressure cylinders that connected to the first driving axle rather than the second, as was typical of most six- or eight-coupled locomotives. Possibly as a result of this, the locomotive did not run smoothly at speeds faster than . In addition, to limit the weight the built-up locomotive frames were lightly constructed, which allowed torsion and flexing that caused the wheel bearings to overheat. This problem was never solved on the PLM engines. However, despite these shortcomings and true to the Mountain type, they were still able to haul heavy passenger trains over gradients at speed and could take an 800 tonne load over a 1 in 200 gradient at .
Based on the Class 241A, the unique PLM Class 241C1, built in 1930, had connecting rods linking the second and third driving axles. This locomotive served as the prototype for development of the post-war standard SNCF Class 241P.