South African Class 10A 4-6-2 - AbsoluteAstronomy.com

In 1910 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 ....

placed ten Class 10-2 4-6-2

4-6-2

4-6-2, in the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of four leading wheels on two axles , six powered and coupled driving wheels on three axles, and two trailing wheels on one axle .These locomotives are also known as Pacifics...

Pacific 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 in service, of which five were built with and five without superheaters. In 1912, when the five non-superheated locomotives were assimilated into the South African Railways, they were renumbered and reclassified to Class 10A.

Manufacturer

Ten heavy 4-6-2 Pacific type passenger locomotives, designed by Central South African Railways (CSAR) Chief Mechanical Engineer (CME) G.G. Elliot and based on the Class 10 design of his predecessor, CSAR Chief Locomotive Superintendent P.A. Hyde, were ordered from the 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) and delivered in 1910. They had plate frames, Belpaire fireboxes and Walschaerts valve gear and were delivered in two variants, five of them using saturated steam while the rest were superheated. They were all classified as Class 10-2 by the CSAR, numbered 665 to 674, and entered service in March 1910.

Reclassification

When they were assimilated into the newly established South African Railways (SAR) in 1912, the five saturated steam locomotives, numbers 665 to 669, were reclassified as Class 10A, numbers 747 to 751. The five superheated locomotives were designated Class 10B

South African Class 10B 4-6-2

In March 1910 the Central South African Railways placed ten Class 10-2 steam locomotives with a 4-6-2 Pacific wheel arrangement in service, of which five were built with and five without superheaters. In 1912, when the five superheated locomotives were assimilated into the South African Railways,...

Characteristics

The Class 10A locomotives were similar to the Class 10, except that their boilers were arranged 7.5 inches (190.5 mm) further forwards and their firebox throats and back plates were sloped instead of being vertical. Like the Class 10

South African Class 10 4-6-2

In 1904 the Central South African Railways placed fifteen Class 10 steam locomotives with a 4-6-2 Pacific wheel arrangement in service. In 1912, when they were assimilated into the South African Railways, they were renumbered but retained their Class 10 classification.-Manufacturer:Fifteen 4-6-2...

, they had 62 inches (1,574.8 mm) driving wheels, the largest yet used in South Africa.

While the Class 10 had outside admission valves, the Class 10A used inside admission piston valves. The valve gear was reversed by means of a vertical steam reversing engine placed on the right-hand running board in line with the steam dome. Two Trevithick

Richard Trevithick

Richard Trevithick was a British inventor and mining engineer from Cornwall. His most significant success was the high pressure steam engine and he also built the first full-scale working railway steam locomotive...

exhaust steam feedwater heaters were mounted on the running boards on either side of the smokebox, and a Weir’s feedwater pump was mounted on the left-hand side of the firebox. The feedwater heaters and the feedwater pump were removed after a few years since the feedwater heaters proved to be troublesome.

Watson standard boilers

In the 1930s many serving locomotives were reboilered with a standard boiler type designed by then CME A.G. Watson as part of his standardisation policy. Such Watson Standard reboilered locomotives were reclassified by adding an "R" suffix to their classification.

All five of the Class 10A locomotives were eventually reboilered with Watson Standard no. 1 boilers. Since the original difference between the Class 10A and Class 10B lay only in the fact that their respective boilers were constructed without or with superheaters, distinction between the two types became unnecessary after reboilering and the reboilered Class 10A locomotives were reclassified to Class 10BR along with similarly reboilered Class 10B locomotives.

An obvious visual difference between an original and a Watson Standard reboilered locomotive is usually the rectangular regulator cover just to the rear of the chimney on the reboilered locomotive. In the case of the Class 10BR locomotives an even more obvious visual difference was the absence of the 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...

hump between the cab and boiler on the reboilered locomotives.

Service

The Class 10A was placed in service hauling passenger trains out of Johannesburg. In service, it was found that the superheated Class 10B sister locomotives could handle almost 25% more load than the saturated steam Class 10A, so much so that double heading passenger trains in the Orange Free State became unnecessary with the Class 10B.

The Class 10A was therefore soon taken off main line passenger service and put to good use on suburban work. After reboilering and reclassification to Class 10BR, most of the rest of their working lives were spent on the Cape Midlands system, where they were used on the main line out of Port Elizabeth.

Two worked as station pilots at Kimberley, but in 1960 they joined the rest of the Class that were by then working the suburban between Port Elizabeth and Uitenhage. In later years they again served on the Reef’s suburban routes while a few were used in the same service around Cape Town, until they were eventually relegated to shunting work. They were scrapped in 1974.

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