South African Class MA 2-6-6-0
Encyclopedia
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.
(NGR) Locomotive Superintendent D.A. Hendrie in 1909 to study Mallet type locomotives and also American locomotive design in general, the American Locomotive Company
(ALCO) supplied the NGR with two experimental locomotives that represented a radical departure from previous NGR locomotive designs. One was the Class American D, later to become the Class 3A
on the South African Railways (SAR), while the other was the first Mallet type compound steam locomotive in South Africa.
. At the time it was the most powerful locomotive in the country.
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
, the rear set of coupled wheels are driven by the smaller high pressure cylinders, from which spent steam is then fed to the larger low pressure cylinders that drive the front set of coupled wheels.
While the results obtained with the Mallet in service were encouraging, it might have been better than adequate if the locomotive had been superheated. Even so, the locomotive’s performance was good enough to warrant subsequent orders for a further five slightly larger and more powerful compound Mallets.
Natal government railways
The Natal Government Railways 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 to Umgeni...
placed a single 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...
Mallet articulated compound steam locomotive
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...
in service. In 1912, when it was assimilated into the South African Railways, it was renumbered and classified as Class MA.
Manufacturer
As a result of a visit to the United States of America by Natal Government RailwaysNatal government railways
The Natal Government Railways 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 to Umgeni...
(NGR) Locomotive Superintendent D.A. Hendrie in 1909 to study Mallet type locomotives and also American locomotive design in general, the American Locomotive Company
American Locomotive Company
The American Locomotive Company, often shortened to ALCO or Alco , was a builder of railroad locomotives in the United States.-Early history:...
(ALCO) supplied the NGR with two experimental locomotives that represented a radical departure from previous NGR locomotive designs. One was the Class American D, later to become the Class 3A
South African Class 3A 4-8-2
Early in 1910 the Natal Government Railways placed a single Class American D 4-8-2 locomotive in service. In 1912, when it was assimilated into the South African Railways, it was renumbered and classified as Class 3A.-Manufacturer:...
on the South African Railways (SAR), while the other was the first Mallet type compound steam locomotive in South Africa.
Characteristics
The locomotive had Walschaerts valve gear, a bar frame and used saturated steam. It was the first acticulated compound steam locomotive to enter service in South Africa and its design and large proportions represented a big advance in motive power on Cape gaugeCape gauge
Cape gauge is a track gauge of between the inside of the rail heads and is classified as narrow gauge. It has installations of around .The gauge was first used by Norwegian engineer Carl Abraham Pihl and the first line was opened in 1862.- Nomenclature :...
. At the time it was the most powerful locomotive in the country.
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, from which spent steam is then fed to the larger low pressure cylinders that drive the front set of coupled wheels.
While the results obtained with the Mallet in service were encouraging, it might have been better than adequate if the locomotive had been superheated. Even so, the locomotive’s performance was good enough to warrant subsequent orders for a further five slightly larger and more powerful compound Mallets.
Service
The locomotive was placed in service banking heavy coal trains between Estcourt and Highlands on the Natal main line. In 1912, when it was taken onto the SAR roster, it was renumbered 1601 and classified as the sole Class MA. It was withdrawn from service in 1927.See also
- Mallet locomotiveMallet locomotiveThe Mallet Locomotive is a type of articulated locomotive, invented by a Swiss engineer named Anatole Mallet ....
- South African Class MB 2-6-6-0South African Class MB 2-6-6-0In 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 2-6-6-0South African Class MC 2-6-6-0In 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 2-6-6-0South African Class MC1 2-6-6-0In 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 2-6-6-2South African Class MD 2-6-6-2In 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 2-6-6-2South African Class ME 2-6-6-2In 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 2-6-6-2South African Class MF 2-6-6-2In 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 2-6-6-2South African Class MG 2-6-6-2In 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 2-6-6-2South African Class MH 2-6-6-2In 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 MJ 2-6-6-0South African Class MJ 2-6-6-0Between 1914 and 1921 the South African Railways placed eighteen Class MJ Mallet articulated compound steam locomotives with a 2-6-6-0 wheel arrangement in branch line service.-Manufacturers:...
- South African Class MJ1 2-6-6-0South African Class MJ1 2-6-6-0In 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