South African Class 8 4-8-0 - AbsoluteAstronomy.com

In 1902 and 1903 the Cape Government Railways

Cape Government Railways

The Cape Government Railways was the government-owned railway operator in the Cape Colony from 1874 until the creation of the South African Railways in 1910.-Private railways:...

placed twenty-three Class 8 steam locomotive

Steam locomotive

A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

s with a 4-8-0

4-8-0

Under the Whyte notation for the classification of steam locomotives, 4-8-0 represents the wheel arrangement of four leading wheels on two axles , eight powered and coupled driving wheels on four axles, and no trailing wheels. The type was nicknamed the Mastodon or Twelve-wheeler in North America....

Mastodon wheel arrangement in service, three on the Cape Western System, eight on the Cape Midland System and twelve on the Cape Eastern System. In 1912, when they were assimilated into the South African Railways, they were renumbered but retained their Class 8 classification.

Evolution

The first Class 8 locomotives of the Cape Government Railways (CGR) were 2-8-0 Consolidation types designed by H.M. Beatty, the Chief Locomotive Superintendent of the CGR from 1896 to 1910. It was later to become the South African Railways (SAR) Class 8X

South African Class 8X 2-8-0

Between 1901 and 1902 the Cape Government Railways placed sixteen Class 8 2-8-0 Consolidation type steam locomotives in service. In 1912, when they were assimilated into the South African Railways, they were renumbered and reclassified to Class 8X...

.

While these first Schenectady and ALCO built 2-8-0 locomotives were being subjected to exhaustive testing on all types of traffic and under varying conditions, some trouble was experienced with the leading two wheeled pony truck and, when designs were prepared at Salt River for a later order for more locomotives, the pony truck was replaced with a four wheeled bogie.

These twenty-three locomotives were the first Class 8 locomotives of the CGR to be built with a 4-8-0 Mastodon type wheel arrangement. In spite of the difference in wheel arrangement, these Consolidations and Mastodons of the CGR were all grouped together into Class 8.

Manufacturer

All these locomotives were built by Neilson, Reid and Company in 1901 and 1902 and delivered in three batches in 1902 and 1903. The first batch of three, numbered 801 to 803, went to the CGR’s Western System in 1902. Of the second batch of ten that arrived in 1902, eight were numbered 358 to 365 and allocated to the Midland System, while the other two became 771 and 772, allocated to the Eastern System. The last batch of ten, numbered 773 to 782, arrived in 1903 and all went to the Eastern System.

They were conceived as mixed traffic locomotives equally suitable for goods and passenger work. They had larger driving wheels than the Class 7

South African Class 7 4-8-0

In 1892 the Cape Government Railways placed six Class 7 steam locomotives with a 4-8-0 Mastodon wheel arrangement in service and between 1892 and 1893 another thirty-two were acquired. They were initially placed in service on the Cape Midland System, but were later distributed between the Cape...

, bar frames, used saturated steam

Saturated steam

In thermodynamics, the state of saturation of a fluid indicates that the fluid is at its boiling point temperature. This term can be applied in several ways:*Saturated liquid: fully in the liquid state but is about to vaporize....

as built and had Stephenson valve gear

Stephenson valve gear

The Stephenson valve gear or Stephenson link or shifting link is a simple design of valve gear that was widely used throughout the world for all kinds of steam engine. It is named after Robert Stephenson but was actually invented by his employees....

. In service it was found that the four wheeled bogies and the slightly shorter fixed wheelbase made them steadier and easier riding than their 2-8-0 predecessors.

Class 8 sub-classes

When these twenty-three locomotives were assimilated into the newly established SAR in 1912, they were renumbered 1069 to 1091, but they retained their Class 8 classification.

The rest of the Class 8 Consolidations and Mastodons of the CGR, together with the Class 8-L1 to 8-L3 4-8-0 Mastodon locomotives of the Central South African Railways

Central South African Railways

From 1902 to 1904, the area of power of Lieutenant-Colonel Sir Percy Girouard later also included the lines of The Netherlands-South African Railway Company; together this dominion covered all lines in the Transvaal that belonged to NZASM ....

, were grouped into nine more different sub-classes by the SAR. The other 4-8-0 locomotives became SAR Classes 8A to 8F and the 2-8-0 locomotives became Classes 8X to 8Z.

Modification

During A.G. Watson’s term as Chief Mechanical Engineer (CME) of the SAR from 1929 to 1936, many of the Class 8 to Class 8F locomotives were equipped with superheated boilers, larger bore cylinders and either inside or outside admission piston valves. The outside admission locomotives had their cylinder bore increased from 18.5 inches (469.9 mm) to 19 inches (482.6 mm) and retained their existing SAR Class 8 classifications, while the inside admission locomotives had their cylinder bore increased to 20 inches (508 mm) and were reclassified by having a "W" suffix added to their existing SAR classifications.

Of the Class 8 locomotives, five were equipped with superheated boilers, 19 inches (482.6 mm) bore cylinders and outside admission piston valves, while retaining their Class 8 classification.

Four locomotives were equipped with superheated boilers, 20 inches (508 mm) bore cylinders and inside admission piston valves and reclassified to Class 8W.

The Class 8 and Class 8W works numbers, renumbering and superheating modifications are shown in the table.

Neilson, Reid built Class 8 & 8W
Works numbers, renumbering and modification
Year	Works No.	CGR No.	CGR System	SAR No.	SAR Model
1901	6111	801	Western	1069
1901	6112	802	Western	1070	Superheated
1901	6113	803	Western	1071
1902	6216	358	Midland	1072
1902	6217	359	Midland	1073	Class 8W
1902	6218	360	Midland	1074	Class 8W
1902	6219	361	Midland	1075
1902	6220	362	Midland	1076
1902	6221	363	Midland	1077	Class 8W
1902	6222	364	Midland	1078	Class 8W
1902	6223	365	Midland	1079
1902	6224	771	Eastern	1080
1902	6225	772	Eastern	1081
1902	6241	773	Eastern	1082	Superheated
1902	6242	774	Eastern	1083
1902	6243	775	Eastern	1084
1902	6244	776	Eastern	1085	Superheated
1902	6245	777	Eastern	1086	Superheated
1902	6246	778	Eastern	1087
1902	6247	779	Eastern	1088	Superheated
1902	6248	780	Eastern	1089
1902	6249	781	Eastern	1090
1902	6250	782	Eastern	1091

Service

In SAR service, the 4-8-0 Class 8 family of locomotives served on every system in the country and in the 1920s became the mainstay of motive power on many branch lines. Their final days were spent in shunting service and by 1972 they were all withdrawn.

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