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Under the Whyte notation for the classification of
steam locomotive A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, oil or, rarely, wood) to heat water in the locomot ...
s by wheel arrangement, is an articulated locomotive using a pair of power units back to back, with the
boiler A boiler is a closed vessel in which fluid (generally water) is heated. The fluid does not necessarily boil. The heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, central h ...
and cab suspended between them. The 2-6-2 wheel arrangement has a single pair of leading wheels in a leading truck, followed by three coupled pairs of
driving wheel On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons (or turbine, in the case of a steam turbine locomotive). On a conventional, non-articulated locomotive, the driving wheels are all coupled ...
s and a pair of trailing wheels in a trailing truck. Since the type was often called the Prairie type, the corresponding Garratt and Modified Fairlie types were usually known as a Double Prairie.


Overview

The wheel arrangement was used on
Garratt A Garratt (often referred to as a Beyer Garratt) is a type of 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 ...
, Modified Fairlie and Union Garratt locomotives.


Garratt locomotives

The was the second most numerous Garratt wheel arrangement to be built, with altogether 238 examples constructed by Beyer, Peacock and Company (BP) and its licensees. Most of them were built to , and the or narrow gauges. None were built to the , but several were built to and gauges. The first examples of the type were two L class Garratts built for the
Tasmanian Government Railways The Tasmanian Government Railways (TGR) was the former operator of the mainline railways in Tasmania, Australia. Formed in 1872, the railway company was managed by the Government of Tasmania, and existed until absorption into the Australian Na ...
in 1912. This wheel arrangement also included the final Garratts to be built by BP, seven South African Class NG G16 locomotives in 1958.


Modified Fairlie locomotives

The Modified Fairlie was first introduced in South Africa, when the South African Railways (SAR) experimented with a modified type of Fairlie locomotive in order to compare the concept to that of the Garratt locomotive in terms of actual performance and maintenance requirements. In essence, the Modified Fairlie was an adaptation of the Kitson-Meyer concept. It was similar in appearance to a Garratt, but with the boiler, cab, coal and water bunkers all mounted on a single rigid frame which pivoted on the engine units, with the pivot centers located approximately at the centre of the rigid wheelbase of each engine unit. In the Garratt design, by comparison, the coal and water bunkers are mounted directly on the engine units and swivel with them, while the boiler, firebox and cab are mounted on a rigid frame which is suspended between the two engine units. The Fairlie locomotive


Union Garratt locomotives

The Union Garratt was a hybrid locomotive, part Garratt and part Modified Fairlie, designed and built for the SAR by Maffei in Munich, Germany. The front end of the locomotive was of a typical Garratt arrangement, with a water tank mounted on the front engine unit’s frame, while the rear end was constructed in the Modified Fairlie fashion, with the coal bunker mounted on a rigid extension of the locomotive’s main frame and with the pivoting rear engine unit positioned beneath the coal bunker.


Usage


Sierra Leone

The
Sierra Leone Government Railway :''This article is part of the history of rail transport by country series'' The Sierra Leone Government Railway operated in Sierra Leone from 1897 to 1974. It was unusual in that it formed a national railway system constructed solely to a Narrow ...
acquired altogether 27 gauge 2-6-2+2-6-2 Garratt locomotives from BP between 1926 and 1956. Seven were delivered in 1926, 1928 and 1929. Six more followed in 1942 and 1943 and fourteen more in 1955 and 1956. Another two were delivered to the
Sierra Leone Sierra Leone,)]. officially the Republic of Sierra Leone, is a country on the southwest coast of West Africa. It is bordered by Liberia to the southeast and Guinea surrounds the northern half of the nation. Covering a total area of , Sierra ...
Development Corporation in 1937, also from BP.


South Africa

The largest user of the type was the South African Railways (SAR) who operated 132 locomotives of this wheel arrangement, spread over fifteen classes. Of these, ten classes were Cape gauge (83 locomotives) and five classes were narrow gauge (49 locomotives). Two of the narrow gauge locomotives were later rebuilt to improve coal combustion and reclassified.


Cape gauge

The 2-6-2+2-6-2 locomotives of the SAR entered service between 1921 and 1929. * In 1921, a single experimental South African Class GB 2-6-2+2-6-2, Class GB Garratt entered service, followed by six more in 1924, designed and built by BP. They were superheated, with
Belpaire firebox The Belpaire firebox is a type of firebox used on steam locomotives. It was invented by Alfred Belpaire of Belgium in 1864. Today it generally refers to the shape of the outer shell of the firebox which is approximately flat at the top and squa ...
es, plate frames and
Walschaerts valve gear The Walschaerts valve gear is a type of valve gear used to regulate the flow of steam to the pistons in steam locomotives, invented by Belgium, Belgian railway mechanical engineering, engineer Egide Walschaerts in 1844. The gear is sometimes name ...
. * In 1923, the New Cape Central Railway (NCCR) placed two Garratts in service, built by BP in 1922 to the design of the Class GB. They were also superheated, with plate frames and Walschaerts valve gear, but heavier and with larger cylinders. In 1925, when the NCCR was amalgamated into the SAR, the two Garratts were designated Class GK. * In 1924, a single experimental Class FC Modified Fairlie entered service, designed and built by
North British Locomotive Company The North British Locomotive Company (NBL, NB Loco or North British) was created in 1903 through the merger of three Glasgow locomotive manufacturing companies; Sharp, Stewart and Company (Atlas Works), Neilson, Reid and Company (Hyde Park Wor ...
(NBL). It had Walschaerts valve gear, a plate frame and was superheated.North British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser * In 1924 and 1925, six Class GC Garratts entered branchline service. They were built by BP in 1924 and were superheated, with Belpaire fireboxes, plate frames and Walschaerts valve gear.South African Railways and Harbours Locomotive Diagram Book, 2’0” & 3’6” Gauge Steam Locomotives, 15 August 1941, as amended * In 1925, a single Class GG Garratt entered service. It was a development of the Class GB with large driving wheels for fast passenger service on mainline duties. Built by BP, it was superheated, with a plate frame, a Belpaire firebox and Walschaerts valve gear. The Class GG was the only Garratt on the SAR to be intended primarily for passenger working. * In 1925 and 1926, fourteen Class GD Garratts entered branchline service. Marginally larger and more powerful than their predecessor Class GC and with a higher axle loading, they were built by BP. They were superheated and had plate frames, Belpaire fireboxes and Walschaerts valve gear. * In 1926, four Class FD Modified Fairlies entered service, designed and built by NBL in 1925. They had Walschaerts valve gear, plate frames and were superheated. * In 1927, ten Class U Union Garratt locomotives were placed in service. The locomotives, designed and built by Maffei, were superheated and had Walschaerts valve gear and bar frames. * In 1927 and 1928, 39 Class GCA Garratts entered branchline service. They were built by Friedrich Krupp AG of Essen in Germany to the same specifications as the Class GC, but with bar frames, round-topped fireboxes and with water tanks and built-up coal bunkers of a different shape. Like the Class GC, they were superheated and had Walschaerts valve gear. * In 1929, five Class GDA Garratts entered branchline service. They were built by Linke-Hofmann Werke AG in Breslau, Germany, to the same specifications as the Class GD, also superheated and with Walschaerts valve gear, but with bar frames, differently shaped coal and water bunkers and round-topped fireboxes.


Narrow gauge

The South African narrow gauge 2-6-2+2-6-2 locomotives entered service between 1927 and 1968. Two were rebuilt in 1989 and 1990 and reclassified. * In 1927, two Class NG G12 Garratts entered service, the smallest Garratts to see service in South Africa. Ordered from BP in 1927, their construction was sub-contracted to Belgian locomotive builders Société Franco-Belge. They were superheated, with outside plate frames, Walschaerts valve gear and round-topped fireboxes.South African Railways and Harbours Narrow Gauge Locomotive Diagram Book, 2’0” Gauge, S.A.R. Mechanical Dept. Drawing Office, Pretoria, 28 November 1932 * In 1927 and 1928, twelve Class NG G13 Garratts entered service on the
Langkloof The Langkloof is a 160 km long valley in South Africa, lying between Herold, a small village northeast of George, and The Heights - just beyond Twee Riviere. History The kloof was given its name by Isaq Schrijver in 1689, and more thorough ...
and
Harding Harding may refer to: People *Harding (surname) *Maureen Harding Clark (born 1946), Irish jurist Places Australia * Harding River Iran * Harding, Iran, a village in South Khorasan Province South Africa * Harding, KwaZulu-Natal United Sta ...
narrow gauge lines. Designed and built by Hannoversche Maschinenbau AG (Hanomag) in consultation with the SAR, the type was to become the standard narrow gauge Garratt in South Africa for the next forty years. They were superheated, with outside bar frames and round-topped fireboxes, and with an extremely compact arrangement of Walschaerts valve gear. The leading wheels were arranged as conventional
pony trucks A Bissell or Bissel truck (also Bissel bogie or Pony truck) is a single-axle bogie which pivots towards the centre of a steam locomotive to enable it to negotiate curves more easily. Invented in 1857 by and usually then known as a ''pony truck ...
, while the inner trailing wheels were built to the Gölsdorf system which allowed the axle some lateral movement. * In 1931, a single light Class NG G14 Garratt entered service. Built by Hanomag in 1930, it was similar to but slightly larger than the , also superheated but with larger bore cylinders, an outside bar frame and a round-topped firebox. * Between 1937 and 1968, 34 Class NG G16 Garratts were placed in service, spread over five orders from three manufacturers. It was almost identical to the Class NG G13, but with all leading and trailing wheels fitted with roller bearing axle boxes and arranged as
pony trucks A Bissell or Bissel truck (also Bissel bogie or Pony truck) is a single-axle bogie which pivots towards the centre of a steam locomotive to enable it to negotiate curves more easily. Invented in 1857 by and usually then known as a ''pony truck ...
.
Société Anonyme John Cockerill Lactalis is a French multinational dairy products corporation, owned by the Besnier family and based in Laval, Mayenne, France. The company's former name was Besnier SA. Lactalis is the largest dairy products group in the world, and is the sec ...
of
Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...
delivered four in 1937. Another 22 were built by BP in 1939, 1951 and 1958, the last seven being the last steam locomotives to be built by BP. The final eight locomotives in 1968 were the last new steam locomotives to be ordered by the SAR and were built by Hunslet-Taylor in Germiston,
Transvaal Transvaal is a historical geographic term associated with land north of (''i.e.'', beyond) the Vaal River in South Africa. A number of states and administrative divisions have carried the name Transvaal. * South African Republic (1856–1902; af, ...
. * In 1989 and 1990, two Class NG G16 Garratts were rebuilt by the
Alfred County Railway Alfred County Railway is an abandoned narrow gauge railway in South Africa, which runs from the southern transport hub of Port Shepstone on the Indian Ocean, via Izotsha and Paddock for to Harding, KwaZulu-Natal. Background South Africa, ri ...
to incorporate a gas producing combustion system (GPCS) and were reclassified to Class NG G16A. The rebuilding was done by mechanical engineer Phil Girdlestone, using technology similar to that used by mechanical engineer David Wardale in the creation of the Class 26 ''Red Devil'' in 1980.Information supplied by Phil Girdlestone


Southern Rhodesia

With altogether 46 locomotives of this wheel arrangement, all built by BP, the second largest user of the Garratt was the
Rhodesia Railways The National Railways of Zimbabwe (NRZ), formerly Rhodesia Railways, is a state-owned company in Zimbabwe that operates the country's national railway system. It is headquartered in the city of Bulawayo. In addition to the headquarters, it has ...
(RR) of
Southern Rhodesia Southern Rhodesia was a landlocked self-governing British Crown colony in southern Africa, established in 1923 and consisting of British South Africa Company (BSAC) territories lying south of the Zambezi River. The region was informally kn ...
, which also operated in
Northern Rhodesia Northern Rhodesia was a British protectorate in southern Africa, south central Africa, now the independent country of Zambia. It was formed in 1911 by Amalgamation (politics), amalgamating the two earlier protectorates of Barotziland-North-West ...
and
Mozambique Mozambique (), officially the Republic of Mozambique ( pt, Moçambique or , ; ny, Mozambiki; sw, Msumbiji; ts, Muzambhiki), is a country located in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi ...
. In 1926, twelve 13th Class 2-6-2+2-6-2 Garratts were ordered by the Beira and Mashonaland and Rhodesia Railways (BMR). They were based at Umtali in
Southern Rhodesia Southern Rhodesia was a landlocked self-governing British Crown colony in southern Africa, established in 1923 and consisting of British South Africa Company (BSAC) territories lying south of the Zambezi River. The region was informally kn ...
to work the difficult section of the Beira line into Mozambique between Umtali and Vila Machado. In 1930, these locomotives were replaced on this duty by 14th Class Garratts, after which they were mainly based at
Salisbury Salisbury ( ) is a cathedral city in Wiltshire, England with a population of 41,820, at the confluence of the rivers Avon, Nadder and Bourne. The city is approximately from Southampton and from Bath. Salisbury is in the southeast of Wil ...
in Southern Rhodesia until their withdrawal from service. The 13th class also operated in
Northern Rhodesia Northern Rhodesia was a British protectorate in southern Africa, south central Africa, now the independent country of Zambia. It was formed in 1911 by Amalgamation (politics), amalgamating the two earlier protectorates of Barotziland-North-West ...
, with a couple being allocated for short periods to
Livingstone Livingstone may refer to: * Livingstone (name), a Scottish surname and a given name. **David Livingstone (1813–1873), Scottish physician, missionary and explorer, after whom many other Livingstones are named Places *Livingstone Falls, on the Con ...
. Two locomotives were also hired out to the Rhokana Corporation copper mine at
Nkana Nkana is a section of the city of Kitwe, Copperbelt Province, Zambia which started off in the early part of the 20th century as a railway station to support the growing complex of copper mining operations. It was named after Chief Nkana, the loc ...
in
Kitwe Kitwe is the third largest city in terms of infrastructure development (after Lusaka and Ndola) and second largest city in terms of size and population (after Lusaka) in Zambia. With a population of 517,543 (''2010 census provisional'') Kitwe is ...
, Northern Rhodesia. These two locomotives were eventually purchased by the mine, one coming to a tragic end in 1950 when it struck a lorry loaded with explosives at a level crossing, causing many deaths since the train carried miners going on shift in an open wagon.Durrant, A.E. (1997). ''The Smoke that Thunders'', (1st ed.). Harare: African Publishing Group. .Pattison, R.G. (2005). ''Thundering Smoke'', (1st ed.). Ilminster, Somerset: Sable Publishing House. . In 1929, the success of the 13th Class led to an improved version being ordered by RR, which the BMR had now become. While of the same wheel arrangement and similar power output as the 13th class locomotives, these sixteen had, amongst other improvements, bar instead of plate frames and round-topped instead of
Belpaire firebox The Belpaire firebox is a type of firebox used on steam locomotives. It was invented by Alfred Belpaire of Belgium in 1864. Today it generally refers to the shape of the outer shell of the firebox which is approximately flat at the top and squa ...
es. These were designated the 14th Class and all of them were initially allocated to Umtali to replace the 13th class Garratts on the line to Vila Machado in Mozambique. From 1939, some of the class were transferred for branchline work in Southern Rhodesia at the Salisbury, Bulawayo and Gwelo depots. In October 1949, the Beira line in Mozambique was taken over by the state-owned ''
Caminhos de Ferro de Moçambique Portos e Caminhos de Ferro de Moçambique (abbreviated CFM; in English Mozambique Ports and Railways) is a state-owned company that oversees the railway system of Mozambique and its connected ports. The rail system is composed of a total of 2,9 ...
'' (CFM). At the same time, the CFM purchased a number of locomotives from RR, including eight 14th Class Garratts, which continued to work on the Beira line from the new depot at Gondola in Mozambique. In 1950, RR ordered a modernised version of the 14th Class for branchline work in Southern Rhodesia. There were eighteen of them and they were designated the 14A Class. From 1979, they were refurbished for shunting work, receiving roller bearings on the driving and coupled axles and, in many cases, larger water tanks and coal bunkers. By 2012 this class, now on the roster of the National Railways of Zimbabwe, still saw occasional service on Bulawayo shunt duties.


References

{{Whyte types 6,2-6-2+2-6-2