The South African Railways Class MB 2-6-6-0 of 1910 was a

articulated steam locomotive An articulated locomotive is a steam locomotive (rarely, an electric locomotive) with one or more engine units that can move independently of the main frame. Articulation allows the operation of locomotives that would otherwise be too large to ...

from the pre- Union era in the

Colony of Natal The Colony of Natal was a British colony in south-eastern Africa. It was proclaimed a British colony on 4 May 1843 after the British government had annexed the Boer Republic of Natalia, and on 31 May 1910 combined with three other colonies t ...

. In November 1910, the

Natal Government Railways The Natal Government Railways (NGR) was formed in January 1877 in the Colony of Natal. In 1877, the Natal Government Railways acquired the Natal Railway Company for the sum of £40,000, gaining the line from the Point to Durban and from Durban ...

placed five Mallet articulated compound steam locomotives in service. In 1912, when they were assimilated into the South African Railways, they were renumbered and designated .Espitalier, T.J.; Day, W.A.J. (1945). ''The Locomotive in South Africa – A Brief History of Railway Development. Chapter VII – South African Railways.''

South African Railways Transnet Freight Rail is a Rail transport in South Africa, South African rail transport company, formerly known as Spoornet. It was part of the South African Railways and Harbours Administration, a state-controlled organisation that employed h ...

and Harbours Magazine, April 1945. p. 274.Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer’s Office, Pretoria, January 1912, pp. 9, 12, 15, 46 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)

Manufacturer

Following on the satisfactory performance of the experimental Mallet compound steam locomotive which had been acquired by the

(NGR) in 1909, a further five similar locomotives were ordered from the

American Locomotive Company The American Locomotive Company (often shortened to ALCO, ALCo or Alco) was an American manufacturer that operated from 1901 to 1969, initially specializing in the production of locomotives but later diversifying and fabricating at various time ...

(ALCO) in 1910. They were delivered in November of that year and numbered in the range from 337 to 341.

Characteristics

Like the previous

Mallet locomotive A Mallet locomotive is a type of compound locomotive, compound articulated locomotive, articulated steam locomotive, invented by the Swiss engineer Anatole Mallet (1837–1919). The front of the locomotive is articulated on a bogie. The Compou ...

, these five had

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 ...

, bar frames and used saturated steam. They differed little from the previous Mallet, basically only in respect of their larger boilers which made them slightly heavier and their tenders with a larger coal capacity. In a compound locomotive, steam is expanded in phases. After being expanded in a high-pressure cylinder and having then lost pressure and given up part of its heat, it is exhausted into a larger-volume low-pressure cylinder for secondary expansion, after which it is exhausted through the smokebox. Compounding Steam Engines In the compound

, the rear set of coupled wheels are driven by the smaller high-pressure cylinders which are fed steam from the steam dome. Their spent steam is then fed to the larger low-pressure cylinders which drive the front set of coupled wheels. By comparison, in the more usual arrangement of simple expansion, steam is expanded just once in any one cylinder before being exhausted through the smokebox.

Service

These five locomotives joined the first Mallet in banking service, working heavy coal trains between

Estcourt Estcourt () is a town in the uThukela District of KwaZulu-Natal Province, South Africa. The main economic activity is farming with large bacon and processed food factories situated around the town. The N3 freeway passes close to the town, link ...

and Highlands on the Natal mainline. To relieve coupler strain, they were used in three-locomotive trains and, in this manner, were able to haul up the one in thirty (3⅓%) gradients on that line.

South African Railways

When the

Union of South Africa The Union of South Africa (; , ) was the historical predecessor to the present-day South Africa, Republic of South Africa. It came into existence on 31 May 1910 with the unification of the British Cape Colony, Cape, Colony of Natal, Natal, Tra ...

was established on 31 May 1910, the three Colonial government railways (

Cape Government Railways The Cape Government Railways (CGR) was the government-owned railway operator in the Cape Colony from 1874 until the creation of the South African Railways (SAR) in 1910. History Private railways The first railways at the Cape were privately ow ...

, NGR and

Central South African Railways The Central South African Railways (CSAR) was from 1902 to 1910 the operator of public railways in the Transvaal Colony and Orange River Colony in what is now South Africa. During the Anglo-Boer War, as British forces moved into the territory of ...

) were united under a single administration to control and administer the railways, ports and harbours of the Union.''The South African Railways – Historical Survey''. Editor George Hart, Publisher Bill Hart, Sponsored by Dorbyl Ltd., Published c. 1978, p. 25. Although the South African Railways and Harbours came into existence in 1910, with Sir William Hoy appointed as its first General Manager, the actual classification and renumbering of all the rolling stock of the three constituent railways were only implemented with effect from 1 January 1912. In 1912, these five locomotives were renumbered in the range from 1602 to 1606 and designated on the South African Railways. They had a relatively short service life and were withdrawn from service by 1924. Their early demise was probably brought forward considerably by the appearance of the Garratt locomotive type on

Cape Gauge A cape is a clothing accessory or a sleeveless outer garment of any length that hangs loosely and connects either at the neck or shoulders. They usually cover the back, shoulders, and arms. They come in a variety of styles and have been used th ...

in 1921.

References

{{Locomotives of South Africa

2210 In contemporary history, the third millennium is the current millennium in the ''Anno Domini'' or Common Era, under the Gregorian calendar. It began on 1 January 2001 ( MMI) and will end on 31 December 3000 ( MMM), spanning the 21st to 30th ...

2-6-6-0 locomotives (1C)C locomotives Mallet locomotives ALCO locomotives Cape gauge railway locomotives Railway locomotives introduced in 1910 1910 in South Africa Scrapped locomotives