South African Class A 4-8-2T

In 1888 the Natal Government Railways placed the first five of its eventual one hundred Class Dübs A 4-8-2T tank steam locomotives in service. The last of the one hundred was delivered in 1899. In 1912, when these locomotives were assimilated into the South African Railways, they were renumbered and reclassified to Class A. In 1915 another two Class A locomotives were built from spare parts.^[1][2]

Manufacturers

The Natal Government Railways (NGR) Class Dübs A 4-8-2T tank locomotive was designed by W. Milne, the Locomotive Superintendent of the NGR from 1877 to 1896, and built by Dübs and Company. The first forty-two locomotives, numbered 49 to 90, were placed in service during Milne’s term and proved to be such good engines that, when G.W. Reid took over as Locomotive Superintendent in 1896, he continued to place further orders for another fifty-eight, numbered 91 to 148. These one hundred locomotives, known on the NGR as the Dübs A, were delivered in ten batches by Dübs between 1888 and 1899.^[1]

As far as is known, the Dübs A locomotives were the first in the world to have a 4-8-2 wheel arrangement, later to become known as the “Mountain” type.^[1]

Modifications

The performance in service of the Class Dübs A was gradually improved by various modifications. New boilers were fitted as the originals wore out, with a working pressure of 160 pounds per square inch (1,100 kilopascals) instead of the as delivered locomotive’s 140 pounds per square inch (965 kilopascals). This increased their tractive effort at 75% boiler pressure from 16,340 pounds-force (72.7 kilonewtons) to 18,670 pounds-force (83.0 kilonewtons). The coal bunkers were also enlarged and the connecting rod big-ends were changed to the marine type to increase ground clearance.^[1]

Beginning in 1905, after D.A. Hendrie took over from Reid as Locomotive Superintendent, these locomotives were gradually fitted with Belpaire fireboxes with wider firegrates. In order to accomplish this, Hendrie raised the boiler’s centre line by 4.5 inches (114 millimetres) and cut away the frame under the firebox to accommodate the wider grates. The wider firebox required that the water tanks also had to be moved out and the opportunity was taken to enlarge the tanks. The cabs were also improved, affording the engine crew better protection. These modified locomotives were known as the Improved Dübs A while still in service with the NGR. In the table below they are listed as "Belpaire" under the "Model" heading.^[1]

Reclassification and renumbering

When the various colonial railroads were amalgamated into the South African Railways (SAR) in 1912, these engines were classified as Class A and were renumbered 97 to 196, the unmodified Dübs A locomotives receiving numbers 97 to 186 and the ten, at the time, already reboilered Improved Dübs A locomotives receiving numbers 187 to 196. In SAR service the Improved Dübs A locomotives became known as the Class A Belpaire. The SAR renumberings are also set out in the table below.^[4][5]

In 1915, to help counter wartime motive power shortages brought about by the diminished ability to order new locomotives from European builders because of the hostilities, another two Class A locomotives were built by the SAR from spare parts in their Durban shops. These two were numbered 332 and 333.^[5]

Service

The Class A was placed in service on the Natal main line, and when they were eventually displaced by more modern locomotives, continued to serve on the Dundee-Hlobane branch line, the Harrismith-Ladysmith section and on the north coast line to Empangeni. The last of the Class A was withdrawn from service in 1962.^[5]

Several continued to serve in industrial use for many years. A few survive in preservation.^[1]

• One, ex NGR 82, SAR 130 named "Patrys", is plinthed at the Reefsteamers Depot in Germiston.^[6]
• Another, ex NGR 88, SAR 136 named “Umbilo”, is in the care of the Umgeni Steam Railway.^[7]

Rebuilding to Class 17 4-8-0T+T

When a shortage of suitable shunting locomotives developed in 1926, the SAR modified twenty-one Class A and Class A Belpaire 4-8-2T locomotives by removing the trailing bissel bogie and coal bunker, shortening the main frame and adding a tender to increase the coal and water capacity.^[5]

Tenders from various scrapped locomotive types were used, probable tender models being three axle Type YB, YC (as in the picture alongside), YE and YE1 tenders, as well as the Type XC1 four axle tender as depicted in the official SAR locomotive diagram.^[2]

These twenty-one rebuilt 4-8-2T locomotives became the SAR’s Class 17 4-8-0T+T tank-and-tender locomotives, numbered 1415 to 1435. They were used as shunting locomotives around Durban and Port Elizabeth until they were withrawn from service by 1961. The locomotives that were rebuilt to Class 17 are also shown in the table.^[5]

Gallery

The main picture shows SAR Class A Belpaire 196 at Masons Mill, Pietermaritzburg, on 10 December 2010. The gallery pictures illustrate the post delivery change that was made to the cab for better crew protection.

See also

• South African Class 17 4-8-0T+T
• Tank locomotive numbering and classification
• The 4-8-2 "Mountain"
• List of South African locomotive classes

References

1. ^ ^{a b c d e f g} Holland, D.F. (1971). Steam Locomotives of the South African Railways, Volume 1: 1859-1910 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 90-93. ISBN 0715353829. 
2. ^ ^{a b c} South African Railways and Harbours Locomotive Diagram Book, 2’0” & 3’6” Gauge Steam Locomotives, 15 August 1941, pp21 & 21A, as amended
3. ^ Pattison, R.G. (1997). The Cape Seventh Class Locomotives (1st ed.). Kenilworth, Cape Town: The Railway History Group. p. 6. ISBN 0958400946. 
4. ^ ^{a b} Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer’s Office, Pretoria, January 1912, pp. 7, 13, 20-22 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)
5. ^ ^{a b c d e} Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 10-11, 26-27, 68. ISBN 0869772112. 
6. ^ Germiston, Reefsteamers Germiston Depot, "PATRYS" SAR Class A No 130
7. ^ Class Dübs "A" "Umbilo"