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53-749: A Garratt locomotive is a type of articulated steam locomotive invented by British engineer Herbert William Garratt that is articulated into three parts. Its boiler , firebox , and cab are mounted on a centre frame or "bridge". The two other parts, one at each end, have a pivot to support the central frame; they consist of a steam engine unit – with driving wheels, trailing wheels, valve gear, and cylinders, and above it, fuel and/or water storage. Articulation permits locomotives to negotiate curves that might restrict large rigid-framed locomotives. The design also provides more driving wheels per unit of locomotive weight, permitting operation on lightly engineered track. Garratt locomotives produced as much as twice

106-501: A class MH Mallet 2-6-6-2 , and a newly arrived class GA Garratt 2-6-0+0-6-2 – the first Garratt of that gauge to enter service in South Africa. The trial was conducted on the line between Durban and Ladysmith , which had gradients as steep as 1 in 30 and curves as tight as 4.5 chains (91 metres) in radius. The Garratt proved the superior locomotive in all regards. The most powerful of all Garratts irrespective of gauge were

159-815: A 65% increase in loading was achieved. In 1911, Beyer, Peacock & Company built six 2-6-0+0-6-2 Garratts for the Western Australian Government Railways . The M class were followed by the Ms class and the Msa class . These locomotives formed the pattern for the Victorian Railways narrow gauge G class and the Australian Portland Cement Garratts. Beyer, Peacock built more than a thousand Garratt or Beyer-Garratt locomotives. The final built to

212-476: A Beyer-Peacock design, in 1967–1968 , were eight 2 ft ( 610 mm ) gauge South African Railways Class NG G16 locomotives. The following list shows known Garratt construction by all manufacturers. Garratts were used in Africa , Asia , Australia , Europe , and South America . No Garratts were used on North American railroads , the most likely explanation being that American rail companies considered

265-505: A career with British colonial railways. Garratt first approached Kitson and Company with his design, but his idea was rejected, perhaps because that company were already committed to the Kitson-Meyer articulated design. He then approached Beyer, Peacock and Company , which were only marginally more interested. In 1907, Beyer, Peacock and Company submitted a proposal for a 2 ft ( 610 mm ) gauge 0-4-0+0-4-0 Garratt to

318-486: A high rate of evaporation. Although at the end of the steam locomotive era, most conventional steam locomotives had reached their maximum in "critical dimensions", the Garratt still had potential for further development, with larger driving wheels, larger boilers, and greater output still achievable. The major theoretical disadvantage of a Garratt (shared with all tank engines ) was that adhesive weight decreases as water

371-404: A normal locomotive, allowing longer continuous runs without needing to stop and empty the ashpan to clear combustion products from the grate. A large firebox and its unrestricted air supply also allowed the Garratt to operate with poor-quality fuel without reducing steaming capacity. Garratts ran equally well in either direction, negating the need for turntables. Often they ran with the cab leading

424-440: A single crew, but to spread the dead weight over many axles and thus avoid excessive loads on the track and under-line bridges, and at the same time retain flexibility of wheelbase to facilitate operation on severely curved sections of line. The Mallet, having driving-wheel units beneath the boiler, retains the limitation in dimensions inherent in the orthodox type of steam locomotive, while the immense length of some of these machines

477-556: A speed of 132 kilometres per hour (82 mph)—a record for any Garratt class (and indeed any articulated class). All three main railways in Angola used Garratts. The largest user was the 3 ft 6 in ( 1,067 mm ) gauge Caminho de Ferro de Benguela . Forty-eight were purchased from Beyer, Peacock between 1926 and 1956. They came in four batches: class 10A (301–306); class 10B (311–324) in 1930; class 10C (331–348) in 1954; and class 10D (361–370). The second-largest user

530-399: A total of 143. More details are in the following table. The East African Railways 4-8-2+2-8-4 59 class Garratts were the largest and most powerful steam locomotives to run on metre gauge, having a large 70-square-foot (6.5-square-metre) grate and a tractive effort of 83,350 pounds-force (370.76 kilonewtons). The 34 oil-fired locomotives remained in regular service until 1980. As of 2020,

583-403: Is itself a handicap. Except with oil firing, ... one cannot put the cab in front. H.W. Garratt ... patented ... the idea of having a single large boiler slung on a cradle carried on two entirely separate engine units. ... The boiler could be developed to ideal proportions, unfettered by any wheels beneath it. It could be kept short, and of large diameter, which is the best possible form for securing

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636-583: Is used up from the front tank and coal and water from the rear tank and bunker. The phenomenon does exist, but was minimised by the adhesion of the multiplicity of driving wheels, sufficient usually to avoid wheel slippage. The Garratt was not alone in the field of articulated locomotives; most notably, articulated locomotives in the United States based on the Mallet design achieved power outputs far exceeding those of Garratts. Away from North America were

689-552: The 20th and 20A classes . Many went to Zambia Railways in 1967 when Rhodesia Railways surrendered the lines in Zambia to its government. Zimbabwe's economic and political situation has extended the life of its Garratts. Five Garratts, including some from the Zimbabwe National Railway Museum , were returned to service in 2004–05 to haul commuter trains. As of 2011 they were performing shunting duties around

742-516: The Chesapeake and Ohio class H-8 , the 2-8-8-4 "Yellowstones", the majority of Southern Pacific 's Cab-forwards , and the Norfolk & Western A-class . Compound expansion , or compound, articulated steam engines like Anatole Mallet 's original idea, consist of two sets of unequally sized cylinders. The smaller pair of cylinders near the cab was fed with high pressure steam directly from

795-531: The Fairlie and Meyer articulated types. Further, similar designs to the Garratt were the Union Garratt, Modified Fairlie, and Golwé . Of these, the closest was the Union Garratt, a type originally prompted by the perceived necessity for a rigid connection between a bunker or tender and a firebox fed by a mechanical stoker. They were, in effect, a hybrid Fairlie and Garratt with the rear bunker attached to

848-567: The Nairobi Railway Museum held two of them. 4-6-4+4-6-4 and 4-8-2+2-8-4 Garratts operated in Mozambique, some built as late as 1956. Rhodesia imported 246 3 ft 6 in ( 1,067 mm ) gauge Garratts of four different wheel arrangements: 2-6-2+2-6-2 s of the 13th, 14th and 14A classes; 4-6-4+4-6-4 s of the 15th class , 2-8-2+2-8-2 s of the 16th, 16A, and 18th classes; and 4-8-2+2-8-4 s of

901-486: The South African Railways ' eight 3 ft 6 in ( 1,067 mm ) gauge GL class locomotives of 1929–30, which delivered 89,130 lbf (396.47 kN) of tractive effort . They were all out of service by the late 1960s. There was also a proposal for a quadruplex super Garratt locomotive with a 2-6-6-2+2-6-6-2 wheel arrangement for South African Railways , but this was never built. On

954-611: The Uganda Protectorate from 1929 to 1948, acquired 77 Garratts between the same years. The Tanganyika Railway also acquired 3 in 1928. In 1948, the railways merged to form the East African Railways and Harbours Corporation , commonly known in the railways context as East African Railways, shown by the letters "EAR" on rolling stock. In addition to the 80 acquired Garratts, East African Railways operated 63 that it purchased new between 1954 and 1956, making

1007-641: The Allegheny H-8 2-6-6-6s were some of the largest steam locomotives ever built, with Big Boy 4014 remaining as the largest, and last of its kind, to still operate. Many schemes for articulation were developed over the years. Of these, the Mallet locomotive and its simple-expansion derivative were the most popular, followed by the Garratt type (mostly built in the United Kingdom , popular throughout Europe , Africa and European colonies), and

1060-465: The Assam Railway. The Trans-Iranian Railway had four 4-8-2+2-8-4 Garratts (class 86) built in 1936. Mauritius had three standard gauge 2-8-0+0-8-2 Garratts that were built in 1927. The Nepal Government Railway (NGR) had 2-6-2+2-6-2 Garratt locomotives manufactured by Beyer, Peacock and Company in 1932 and 1947. The Royal State Railway of Siam acquired 8 Garratts built by

1113-907: The GE class, was built for Burma Railways in 1949, but was diverted to the Assam Railway in India. Two 0-6-0+0-6-0 2 ft 6in gauge Beyer-Garratts were supplied to the Buthidaung-Maungdaw Tramway which became the Arakan Light Railway. BP works Nos. 5702 & 5703 of 1913 refer. Ceylon had 10 Garratts: an H1 class 2 ft 6 in ( 762 mm ) 2-4-0+0-4-2 in 1924, a C1 class 5 ft 6 in ( 1,676 mm ) 2-6-2+2-6-2 in 1927 and eight more C1 class 5 ft 6 in gauge 2-6-2+2-6-2 s in 1945. India had 83 Garratts. One 5 ft 6 in ( 1,676 mm ) gauge 2-6-2+2-6-2

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1166-602: The GT class on the Bengal Assam Railway . Three types of Garratt were supplied for war service on the BAR: ten MWGL class 2-8-0+0-8-2 locomotives; twelve MWGH 2-8-2+2-8-2 locomotives; and 18 MWGX class 4-8-2+2-8-4 War Department standard light Garratts. Of these, only nine MWGX stayed in India, with the remainder transferred to Burma. After the war, the four Burma Railways GE class 4-8-2+2-8-4 s were diverted to

1219-430: The Garratt's coal and water capacities insufficient for their requirements. The Garratt was most widely used in Africa : large numbers were in South Africa, Rhodesia (now Zimbabwe) and Algeria, and smaller numbers in Angola, Congo, Ghana, Ivory Coast, Kenya, Libya, Madagascar, Mozambique, Nigeria, Senegal, Sierra Leone, Sudan, Uganda and Zaïre. In Algeria, 29 4-6-2+2-6-4 Garratts, constructed between 1936 and 1941 by

1272-669: The German company Henschel during 1929–1937 for heavy freight duties in the Pak Chong highland areas. One has been preserved; it is displayed at Kanchanaburi railway station . Turkish State Railways had just one standard gauge 2-8-0+0-8-2 Garratt that was built in 1927. The Australian Standard Garratt (ASG) was designed in Australia as an emergency measure during World War II , when demand on 1067 mm ( 3 ft 6 in ) narrow-gauge railways could not be met by

1325-534: The Mallet design on account of the geometry of the design. When swinging around curves, the boiler and cab unit moved inward, reducing the centrifugal force, whereas the Mallet's forward articulated unit moved out as the locomotive rounded curves. As O.S. Nock wrote, the Garratt type holds several advantages over the Mallet type: This [the Mallet] was so designed to provide a very large engine unit, to be managed by

1378-580: The New South Wales Government Railways, which was not proceeded with. The following year a design for a 2 ft gauge Mallet locomotive was submitted in reply to an enquiry from the Government of Tasmania . The company then proposed a Garratt design based on, but a little heavier than, the design for New South Wales, with capacity to negotiate curves of 99 ft (30.18 m) radius and 1 in 25 gradients. The proposal

1431-644: The Société Franco-Belge de Matériel de Chemins de Fer at Raismes in Northern France, operated until the Algerian independence war caused their withdrawal in 1951. This class, designated 231-132BT, was streamlined and featured Cossart motion gear, mechanical stokers and 1.8 m (5 ft 11 in) driving wheels, the largest of any Garratt class. On a test in France, one of these achieved

1484-493: The South African Railways GMA/M 4-8-2+2-8-4 Garratts of 1954, which developed a tractive effort of 60,700 lbf (270 kN). Following modifications in 1958 to thirty AD60s, their tractive effort was increased to 63,016 lbf (280.31 kN). These locomotives remained in service until the early 1970s with a replacement "6042" using the boiler cradle of 6043 (The original was scrapped in 1968)

1537-512: The Western Australian Government Railways for 14 years, during which periods many of the defects were rectified or components replaced. New South Wales Government Railways introduced the 4-8-4+4-8-4 AD60 Garratt in 1952, built by Beyer, Peacock. The AD60 weighed 265 tonnes, with a 16-tonne axle loading. As delivered, it developed a tractive effort of 60,000 lbf (270 kN)), not as powerful as

1590-876: The available stock of locomotives. The ASG was used on the railways of Queensland , Western Australia and Tasmania and, after the war, on the South Australian Railways , the Emu Bay Railway in Tasmania and the Fyansford Cement Works railway in Victoria. The first was built in a record-breaking four months, entering service in September 1943. Considerable differences between the states, especially in loading gauges , sharpness of curves and limits to axle load, compromised

1643-415: The boiler (sometimes called [fuel] bunker leading), especially on routes with tunnels. Most Garratts were designed for freight or mixed traffic, but several Garratt classes were designed for passenger service. A French-built Algerian Railways Garratt holds the world speed record for an articulated locomotive at 132 kilometres per hour (82 mph). Garratts operating at higher speeds had one advantage over

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1696-421: The boiler and then the steam was passed into a pair of low-pressure cylinders at the front, with larger diameter to offset the lower pressure, before exhausting through the smokestack. While the thermal efficiency was greatly improved through the compound use of steam in Mallet designs, the large low-pressure cylinders posed unique limitations, both in terms of loading gauge (the cylinders could only be as large as

1749-525: The boiler unit and the power units. However, Beyer, Peacock's engineers solved them after studying a description of the spherical steam joints used on a Fairlie locomotive. The third Garratt (another 0-4-0+0-4-0 , like the first two) was built in 1910 for the Darjeeling Himalayan Railway and given the class letter "D". The power output was intended to be double that of the line's existing 0-4-0 ST locomotives, but only

1802-575: The city of Bulawayo. On the Sierra Leone Government Railway , this 2 ft 6 in ( 762 mm ) gauge system had 2-6-2+2-6-2 Garratts starting in the 1920s and in the middle 1950s purchased 14 4-8-2+2-8-4 Garratts. In 1921, the South African Railways held a comparative trial between three 3 ft 6 in ( 1,067 mm ) locomotives: a class 14B 4-8-2 tender engine;

1855-403: The design, as did the inclusion of features that led to unreliability. A royal commission convened in 1946 to investigate the locomotives, whose deficiencies had caused enginemen to go on strike, concluded: "It is obvious when one analyses the evidence that the new Australian Standard Garratt has put up a poor performance. At times these locomotives have done good work but they cannot compare with

1908-405: The distances between both the main steam pipe and the high-pressure cylinders and between the high-pressure and low-pressure cylinders. The latter feature made the locomotive unnecessarily complicated and placed the high-pressure cylinders directly underneath the cab, making it uncomfortably hot for the crew on the rare days when Tasmania's West Coast Range was warm. Only one more Garratt locomotive

1961-534: The frame instead of being carried on the rear bogie. The class GH and class U Union Garratts of the South African Railways were examples. Herbert William Garratt, a British locomotive engineer, invented the articulated locomotive concept that bore his name, for which he was granted a patent (no. 12079). At the time, he was the New South Wales Railways ' inspecting engineer in London following

2014-580: The hardest-pulling steam locomotives ever built. The first Garratt locomotives constructed, the Tasmanian Government Railways K class were also compound locomotives, but were complicated as a result. All subsequent Garratts were simple engines only. There were various types of articulated geared steam locomotive , including: There are several classes of articulated electric locomotives of generally two types: The conventional electric and diesel locomotive dual bogie design uses

2067-537: The last withdrawn in February 1973. Oberg wrote he witnessed an AD60 clear a dead 1220-tonne double-headed diesel freight (total weight 1450 tonnes) from a 1 in 55 grade without wheel slip. Four AD60's survive today: 6029 (which operates occasionally out of Thirlmere), 6039 (under private ownership at Dorrigo Museum), 6040 (on static display at THNSW, Thirlmere), & 6042 (also owned by the Dorrigo museum but sitting in

2120-433: The length of the locomotive and carried the boiler, fuel and water. The front engine unit swivelled under the boiler and smokestack , in a similar manner to a Meyer and looking somewhat like a Mallet ; in contrast a Garratt had its front bogie in front of the boiler. The rear engine unit was placed underneath the tender, in a manner similar to a Garratt; however, while a Garratt carried both coal and water directly on

2173-646: The middle of a field in Forbes, NSW). Queensland Railways operated 30 Beyer Garratt locomotives. These were mainly based in the Rockhampton area. Articulated locomotive Articulated locomotives saw service in many nations, but were very popular on narrow-gauge railways in Europe. The largest examples were developed in the United States, where the Union Pacific Big Boy 4-8-8-4s and

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2226-686: The old Beyer Garratts, which have such an enduring record of service." Many were withdrawn in September 1945, weeks after the war ended. Those sold to the South Australian Railways in 1952 (as a stopgap) served for only 18 months, but others lasted longer: on the Queensland Government Railways for two years, at Fyansford and Emu Bay for 11 years, on the Tasmanian Government Railways (including some ex-QR engines) for 13 years, and on

2279-453: The rear bogie, the Golwé had its fuel bunker mounted on the central frame. The water tank was mounted directly on the rear steam bogie and embraced the fuel bunker and rear end of the main frame. The rear bogie cylinders were placed under the cab, at the front of the rear unit. A float-controlled automatic device increased the cut-off of the rear cylinders to prevent slipping when the water tank

2332-760: The same general configuration as the Meyer design but is not considered to be articulated. Golw%C3%A9 locomotive The Golwé was a type of articulated steam locomotive manufactured in Belgium for use in French West African colonies. The design was patented in 1924, as the work of G. Goldschmidt and A. Weber, managing director and chief engineer of the Société Haine St. Pierre  [ fr ] in Belgium. A single rigid frame ran

2385-464: The track and track-side infrastructure allowed) and in terms of performance at speed. The large and consequently heavier pistons caused stability issues at higher speed, which generally limited compound expansion articulated locomotives to below 30 or 40 miles per hour. A notable exception to this was to be found in later iterations of Norfolk & Western Y-class 2-8-8-2s, which could and did often exceed 50 miles per hour in service as well as being one of

2438-421: The tractive effort of the largest conventional locomotives of railways that introduced them, reducing the need for multiple locomotives and crews. The principal benefit of the Garratt design is that the boiler and firebox unit are slung between the two engine units. A further advantage is that the firebox and ashpan are not restricted in dimensions by running gear; the ashpan can have much larger capacity than on

2491-1037: The two foot gauge lines in South Africa, several successive classes of Garratts were made, of which the NG G16 became the most powerful steam locomotive ever built for the gauge. Some of these were imported to Wales for the Welsh Highland Railway . Sudan operated at least one 4-6-4+4-6-4 Garratt. Burma had 43 metre gauge Garratts. Five B class 2-8-0+0-8-2 Garratts went to the Burma Railway Company between 1924 and 1927, with seven more built by Krupp of Germany in 1929. They were followed by 31 locomotives transferred from India for War Department service: ten 2-8-0+0-8-2 locomotives, class GB (ex-Indian class MWGL); twelve 2-8-2+2-8-2 locomotives of class GC (ex-Indian class MWGH); and nine 4-8-2+2-8-4 locomotives of class GD (ex-Indian class MWGX). A class of four 4-8-2+2-8-4 locomotives,

2544-441: The various geared steam locomotive types, the latter largely used in logging, mining and industry. Most other types saw only limited success. As distinct from articulated locomotives, a non-articulated locomotive is referred to as a straight or rigid locomotive. The major types of articulated locomotive are: Simple expansion , or simple, articulated steam engines had two sets of equally sized cylinders. High-pressure steam

2597-508: Was accepted, and two locomotives were built in 1909, which became the K class . The Tasmanian Railways stipulated two features that were not in Herbert Garratt's original concept. The first was a compound configuration in which two high-pressure cylinders were on the rear engine unit and a pipe led to two larger, low-pressure cylinders on the front engine unit. The second was to have the cylinders facing inwards, which would reduce

2650-497: Was built for the Indian State in 1925. The 5 ft 6 in gauge Bengal Nagpur Railway had 32 Garratts: a pair of HSG class 2-8-0+0-8-2 locomotives built in 1925; 16 N class and 10 NM class 4-8-0+0-8-4 locomotives built in 1930–31 and four P class 4-8-2+2-8-4 locomotives built in 1939. The metre gauge Assam-Bengal Railway had six T class 2-6-2+2-6-2 locomotives built in 1927. They later became

2703-527: Was produced with compound propulsion (by Beyer, Peacock & Co. in 1927 for Burma Railways ). The company built no more Garratts with inward-facing cylinders, but two Garratts operated by the Southern Fuegian tourist railway at Ushuaia in Argentina, largely based on the K class, have that feature. Early design and construction difficulties involved the steam-tight flexible connections between

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2756-510: Was supplied to all cylinders and exhausted out of the stack once it had been used. The American simple-expansion articulated, thanks largely to the smaller mass of the forward cylinders when compared to the compound-expansion Mallets allowing for higher piston speed, were generally better suited for high speed than their compound cousins. Examples of the "simple mallet" design include the Union Pacific Big Boys and Challengers ,

2809-670: Was the Caminhos de Ferro de Luanda , which bought six 4-8-2+2-8-4 locomotives (501–506) from Beyer, Peacock in 1949, and six more (551–556) from Krupp of Germany in 1954. The third user was the Caminhos de Ferro de Moçâmedes , who bought six 4-8-2+2-8-4 locomotives (101–106) from Henschel & Son of Germany. Garratts operated on 3 ft 6 in ( 1,067 mm ) gauge through trains from South Africa to Rhodesia. Kenya and Uganda Railways and Harbours , which operated railways in British East Africa and

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