Between 1914 and 1921 the South African Railways placed eighteen Class MJ Mallet articulated compound steam locomotives

Compound locomotive

A compound engine unit is a type of steam engine where steam is expanded in two or more stages.A typical arrangement for a compound engine is that the steam is first expanded in a high-pressure cylinder, then having given up heat and losing pressure, it exhausts directly into one or more larger...

 with a 2-6-6-0

2-6-6-0

In Whyte notation for the classification of steam locomotives by wheel arrangement, a 2-6-6-0 is a locomotive with one pair of unpowered leading wheels, followed by two sets of three pairs of powered driving wheels, and no trailing wheels...

 wheel arrangement in branch line service.

Manufacturers

The Class MJ 2-6-6-0 Mallet articulated compound steam locomotive was designed by D.A. Hendrie, Chief Mechanical Engineer (CME) of the South African Railways (SAR) from 1910 to 1922. Ten of these branch line locomotives were ordered from Maffei but, as a result of the outbreak of World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

, only two could be delivered from Germany in 1914, numbered 1651 and 1652 with works numbers 3452 and 3453.

The order for the remaining eight was then transferred to North British Locomotive Company

North British Locomotive Company

The North British Locomotive Company was created in 1903 through the merger of three Glasgow locomotive manufacturing companies; Sharp Stewart and Company , Neilson, Reid and Company and Dübs and Company , creating the largest locomotive manufacturing company in Europe.Its main factories were...

 (NBL) in Scotland, who delivered them in 1917, numbered 1653 to 1660.

The works numbers for the eight NBL built locomotives are recorded as 21248 to 21255, but these numbers are in conflict with the NBL works numbers 21246 to 21275 that were allocated to thirty 2-8-2T locomotives, numbered 5381 to 5410 and built by NBL in 1917 for the Paris-Orleans railway

Compagnie du chemin de fer de Paris à Orléans

The Compagnie du chemin de fer de Paris à Orléans was an early French railway company.It merged with the Chemin de Fer du Midi to form the Chemin de Fer de Paris à Orléans et du Midi in 1934...

 in France.

After the cessation of hostilities in 1918, Maffei approached the SAR and requested that the balance of the original order, which had been built in 1914 but could not be delivered because of the war, also be accepted. These eight locomotives were subsequently delivered in 1921, numbered 1674 to 1681 with works numbers 3454 to 3461.

They were superheated and had Walschaerts valve gear. Unlike most of the other SAR Mallet classes which had round top fireboxes, they had Belpaire firebox

Belpaire firebox

The Belpaire firebox is a type of firebox used on steam locomotives. It was invented by Alfred Belpaire of Belgium. It has a greater surface area at the top of the firebox, improving heat transfer and steam production...

es.

Compound expansion

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. 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.

In the compound Mallet locomotive

Mallet locomotive

The Mallet Locomotive is a type of articulated locomotive, invented by a Swiss engineer named Anatole Mallet ....

, 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 that drive the front set of coupled wheels.

Service

With its light axle loading, the Class MJ was intended for branch line working. Most of them were placed in service in the Eastern Cape, but four went to Natal and are believed to have worked on the Eshowe branch line.

Two of the Class MJ locomotives, NBL built number 1655 and Maffei built number 1674, had the distinction of being the last two Mallet locomotives to remain in SAR service. They were scrapped in the East London workshops in 1962 after having worked on the branch line between Amabele and Umtata in the Transkei and then having spent their last days in shunting service in East London.

See also

• Mallet locomotive
  Mallet locomotive
  The Mallet Locomotive is a type of articulated locomotive, invented by a Swiss engineer named Anatole Mallet ....
  
  
• South African Class MA 2-6-6-0
  South African Class MA 2-6-6-0
  In 1909 the Natal Government Railways placed a single 2-6-6-0 Mallet articulated compound steam locomotive in service. In 1912, when it was assimilated into the South African Railways, it was renumbered and classified as Class MA.-Manufacturer:...
  
  
• South African Class MB 2-6-6-0
  South African Class MB 2-6-6-0
  In 1910 the Natal Government Railways placed five 2-6-6-0 Mallet articulated compound steam locomotives in service. In 1912, when they were assimilated into the South African Railways, they were renumbered and classified as Class MB.-Manufacturer:...
  
  
• South African Class MC 2-6-6-0
  South African Class MC 2-6-6-0
  In 1912 the South African Railways placed ten Class MC Mallet articulated compound steam locomotives with a 2-6-6-0 wheel arrangement in service.-Manufacturer:...
  
  
• South African Class MC1 2-6-6-0
  South African Class MC1 2-6-6-0
  In 1914 the South African Railways placed fifteen Class MC1 Mallet articulated compound steam locomotives with a 2-6-6-0 wheel arrangement in service.-Manufacturer:...
  
  
• South African Class MD 2-6-6-2
  South African Class MD 2-6-6-2
  In March 1910 the Central South African Railways placed a single experimental Mallet articulated compound steam locomotive with a 2-6-6-2 wheel arrangement in service...
  
  
• South African Class ME 2-6-6-2
  South African Class ME 2-6-6-2
  In January 1912 the South African Railways placed a single Class ME Mallet articulated steam locomotive with a 2-6-6-2 wheel arrangement in service.-Manufacturer:...
  
  
• South African Class MF 2-6-6-2
  South African Class MF 2-6-6-2
  In 1911 the Central South African Railways placed nine Mallet articulated compound steam locomotives with a 2-6-6-2 wheel arrangement in service. In 1912, when they were assimilated into the South African Railways, they were renumbered and classified as Class MF...
  
  
• South African Class MG 2-6-6-2
  South African Class MG 2-6-6-2
  In 1911 the Central South African Railways placed a single experimental Mallet articulated compound steam locomotive with a 2-6-6-2 wheel arrangement in service...
  
  
• South African Class MH 2-6-6-2
  South African Class MH 2-6-6-2
  In 1915 the South African Railways placed five Class MH Mallet articulated compound steam locomotives with a 2-6-6-2 wheel arrangement in service.-Manufacturer:...
  
  
• South African Class MJ1 2-6-6-0
  South African Class MJ1 2-6-6-0
  In 1918 the South African Railways placed eight Class MJ1 Mallet articulated compound steam locomotives with a 2-6-6-0 wheel arrangement in branch line service.-Manufacturer:...
  
  
• Articulated locomotive numbering and classification
• The 2-6-6-0 Mallet
• List of South African locomotive classes