South African Class DS

12 ft 11+3⁄4 in (3,956 mm)Axle load16 LT 12 cwt (16,870 kg)Adhesive weight66 LT 8 cwt (67,470 kg)Loco weight66 LT 8 cwt (67,470 kg)Fuel typeDieselFuel capacity455 imp gal (2,070 L)Prime moverTwo MAN 265 hp (198 kW)Engine typeDieselGeneratorTwo AEG 110 kW (150 hp) main
Two AEG 12 kW (16 hp) auxiliaryTraction motorsFour AEGCylindersEightGear ratio5.67:1CouplersAAR knuckle

Performance figures
Power output	410 hp (310 kW)
Tractive effort:
• Starting	35,200 lbf (157 kN)
Factor of adh.	4•2

Career
Operators	South African Railways
Class	Class DS
Number in class	1
Numbers	D137, renumbered D513
Delivered	1939
First run	1939
Scrapped	November 1966

The South African Railways Class DS of 1939 was a diesel-electric locomotive.

The first diesel-electric locomotive on the South African Railways was a single Class DS AEG diesel-electric shunting locomotive which was placed in service at the Congella yards near Durban in 1939.^[1]^[2]

Diesel-steam comparison

Around 1935, the question of purchasing diesel locomotives for the South African Railways (SAR) was seriously considered. Even though South Africa was a coal-rich country with, at the time, the lowest pit-head prices in the world and no oil wells, there were definite advantages in favour of the diesel-electric locomotive. It did not need to take water en route, could undertake very long runs without the need to refuel or change locomotives and had a much higher rate of availability.^[2]

The first costs were much in favour of steam locomotives, for which it decreased in cost per unit of power as the size increased, an advantage that the diesel-electric did not seem to have. Large diesel-electric locomotives of more than 1,500 horsepower (1,100 kilowatts) were usually three to four times greater in first cost than steam locomotives of equal power. In addition, unless it was supercharged, a diesel lost 3% of its rated power output with every increase of 1,000 feet (305 metres) in altitude.^[2]

Manufacturer

As a result of the problems experienced to obtain adequate water supplies of good quality in the arid regions of South Africa and South West Africa, particularly on the section from De Aar via Upington to Keetmanshoop, the SAR decided to experiment with diesel-powered traction and introduced its first two diesel-electric shunting locomotives in 1939.^[1]^[2]^[3]

The first of these was a single twin-engined centre-cab locomotive with a Bo-Bo wheel arrangement which was ordered from Allgemeine Elektricitäts-Gesellschaft (AEG) in Berlin for use as a shunting engine. The locomotive was designated Class DS and was initially numbered D137, but it was soon renumbered to D513. Both numbers were in the electric locomotive number range, but with a "D" for diesel instead of an "E" for electric number prefix.^[1]^[2]

Characteristics

The 66 long tons 8 hundredweight (67,470 kilograms) locomotive was powered by two Maschinenfabrik Augsburg-Nürnberg (MAN) 265 horsepower (198 kilowatts) eight-cylinder diesel engine prime movers, one on either side of the cab. An AEG 110 kilowatts (150 horsepower) main generator and an AEG 12 kilowatts (16 horsepower) auxiliary generator were mounted directly in line between each engine and the cab. Each engine was water-cooled with a fan which was belt-driven by its engine and which drew air through a conventional radiator.^[1]^[2]

The bogies were very similar to those of the Class 1E electric locomotive, each with two DC traction motors arranged in series. Each bogie axle was driven by a force-ventitated axle-suspended DC traction motor, with the two motors on each bogie electrically arranged in series. The cab was equipped with mechanically interlocked dual controls to enable operation in either direction.^[1]^[2]

Service

The locomotive was placed in service at the Congella yards near Durban. Even though performance-wise the results were rather disappointing, it nevertheless remained in service for 28 years.^[1]^[2]

The first diesel-electric locomotive on the SAR eventually found its way to Cape Town where it was scrapped at the Salt River Works in November 1966.^[1]^[2]

Illustration

Class DS no. D137, c. 1940

References

^ ^a ^b ^c ^d ^e ^f ^g Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. p. 136–137. ISBN 0869772112.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Espitalier, T.J.; Day, W.A.J. (1947). The Locomotive in South Africa – A Brief History of Railway Development. Chapter VII – South African Railways (Continued). South African Railways and Harbours Magazine, March 1947. pp. 230–231.
^ South African Railways and Harbours Locomotive Diagram Book, 2'0" & 3'6" Gauge Steam Locomotives, 15 August 1941, as amended

External links

Media related to South African Class DS at Wikimedia Commons

Locomotives of South Africa

Steam

7' ¼" gauge	East London 0-4-0VB Table Bay 0-4-0ST Table Bay 0-4-0T Table Bay 0-4-0WT
Standard gauge	Cape 0-4-0T Blackie Cape 0-4-2 Cape 2-4-0T CGR 0-4-0ST Aid Natal 0-4-0ST Durban Natal 0-4-0WT Natal Natal 4-4-0T Perseverance
Cape gauge Tank engines	CGR 0-4-0ST 1873 CGR 0-4-0ST 1874 CGR 0-4-0ST 1881 CGR 0-4-0ST 1881 Coffee Pot CGR 0-6-0ST CGR 0-6-0T CGR 2-6-0ST 1900 CGR 2-6-0ST 1902 CGR 1st Class 0-4-0ST 1875 CGR 1st Class 0-4-0ST 1876 CGR 1st Class 2-6-0ST CGR 1st Class 4-4-0T CGR 2nd Class 4-4-0T CGR 3rd Class 2-6-0T CGR Railmotor CSAR Class C CSAR Class E CSAR Rack 4-6-4RT CSAR Railmotor Durban's Congella Durban's Edward Innes Durban's John Milne Durban's Sir Albert Port Elizabeth 0-4-0ST Kowie Railway 0-6-0T Kowie Railway 4-4-0T Metropolitan & Suburban 4-6-2T NGR 2-6-0T Durban & Pietermaritzburg NGR Class I 2-6-2T NGR Class K 0-4-0ST NGR Class K 0-6-0ST NGR Class K 2-6-0T NZASM 10 Tonner NZASM 13 Tonner NZASM 14 Tonner NZASM 18 Tonner NZASM 19 Tonner NZASM 32 Tonner NZASM 40 Tonner PPR 26 Tonner PPR 35 Tonner Portuguese SAR Class A SAR Class B SAR Class C SAR Class C1 SAR Class C2 SAR Class D SAR Class E SAR Class F SAR Class G SAR Class H SAR Class H1 SAR Class H2 SAR Class J SAR Class K SAR Railmotor SAR Dock 0-4-0ST SAR Dock 0-4-0T SWA 2-8-0T
Cape gauge Tender engines	CGR 1st Class 2-6-0 1876 BP CGR 1st Class 2-6-0 1876 Kitson CGR 1st Class 2-6-0 1879 CGR 1st Class 2-6-0 1891 CGR 1st Class 4-4-0 CGR 1st Class 4-4-0TT CGR 2nd Class 2-6-2TT CGR 3rd Class 4-4-0 1883 CGR 3rd Class 4-4-0 1884 CGR 3rd Class 4-4-0 1889 CGR 3rd Class 4-4-0 1898 CGR 3rd Class 4-4-0 1901 CGR 3rd Class 4-4-0 1903 CGR 4th Class 4-4-2 CGR 4th Class 4-6-0TT 1880 CGR 4th Class 4-6-0TT 1882 CGR 4th Class 4-6-0TT 1882 Joy CGR 4th Class 4-6-0TT 1884 CGR 5th Class 4-6-0 1890 CGR 5th Class 4-6-0 1891 NGR Havelock NGR Class I SAR Class Exp 1 SAR Class Exp 2 SAR Class Exp 3 SAR Class Exp 4 SAR Class Exp 5 SAR Class Exp 6 SAR Class S SAR Class S1 SAR Class S2 SAR Class 1 SAR Class 1A SAR Class 1B SAR Class 2 SAR Class 2C SAR Class 3 SAR Class 3A SAR Class 3B SAR Class 4 SAR Class 4A SAR Class 5 SAR Class 5A SAR Class 5B SAR Class 6 SAR Class 6A SAR Class 6B SAR Class 6C SAR Class 6D SAR Class 6E SAR Class 6F SAR Class 6G SAR Class 6H SAR Class 6J SAR Class 6K SAR Class 6L SAR Class 6Y SAR Class 6Z SAR Class 7 SAR Class 7A SAR Class 7B SAR Class 7C SAR Class 7D SAR Class 7E SAR Class 7F SAR Class 8 SAR Class 8A SAR Class 8B SAR Class 8C SAR Class 8D SAR Class 8E SAR Class 8F SAR Class 8R SAR Class 8X SAR Class 8Y SAR Class 8Z SAR Class 9 SAR Class 10 SAR Class 10A SAR Class 10B SAR Class 10C SAR Class 10D SAR Class 11 SAR Class 12 SAR Class 12A SAR Class 12B SAR Class 13 SAR Class 14 SAR Class 14A SAR Class 14B SAR Class 14C 1st SAR Class 14C 2nd SAR Class 14C 3rd SAR Class 14C 4th SAR Class 15 SAR Class 15A SAR Class 15B SAR Class 15C SAR Class 15CA SAR Class 15E SAR Class 15F SAR Class 16 SAR Class 16A SAR Class 16B SAR Class 16C SAR Class 16D SAR Class 16DA 1928 SAR Class 16DA 1930 SAR Class 16E SAR Class 17 SAR Class 18 SAR Class 19 SAR Class 19A SAR Class 19B SAR Class 19C SAR Class 19D SAR Class 20 SAR Class 21 SAR Class 23 SAR Class 24 SAR Class 25 SAR Class 25NC SAR Class 26 SAR Katanga SWA 2-8-0
Cape gauge Articulated engines	CGR Fairlie CGR Kitson-Meyer SAR Class FC SAR Class FD SAR Class GA SAR Class GB SAR Class GC SAR Class GCA SAR Class GD SAR Class GDA SAR Class GE SAR Class GEA SAR Class GF SAR Class GG SAR Class GH SAR Class GK SAR Class GL SAR Class GM SAR Class GMA SAR Class GO SAR Class HF SAR Class KM SAR Class MA SAR Class MB SAR Class MC SAR Class MC1 SAR Class MD SAR Class ME SAR Class MF SAR Class MG SAR Class MH SAR Class MJ SAR Class MJ1 SAR Class U
2' 6" gauge	Cape Copper John King & Miner Cape Copper Britannia Cape Copper Caledonia Cape Copper Clara Cape Copper Condenser Cape Copper Scotia Namaqua Copper Pioneer Walvis Bay 2-4-2T Hope
2' & 600mm gauges	ACR Class NG-G16A CGR NG 0-4-0T CGR NG 0-6-0T CGR NG 4-6-2T CGR Type A 2-6-4T CGR Type C 0-4-0T NGR Class N 4-6-2T SAR Dutton SAR NG 0-4-0T SAR Class NG1 SAR Class NG2 SAR Class NG3 SAR Class NG4 SAR Class NG5 SAR Class NG6 SAR Class NG7 SAR Class NG8 SAR Class NG9 SAR Class NG10 SAR Class NG-G11 SAR Class NG-G12 SAR Class NG-G13 SAR Class NG-G14 SAR Class NG15 SAR Class NG-G16 SWA Class Ha SWA Class Hb SWA Class Hc SWA Class Hd SWA Jung SWA Zwillinge

Electric

Amcoal Class E38

Gas-electric

SAR Gas-electric

Diesel

Cape gauge Diesel-electric	PRASA Class Afro 4000 SAR Class DS SAR Class DS1 SAR Class 31-000 SAR Class 32-000 SAR Class 32-200 SAR Class 33-000 SAR Class 33-200 SAR Class 33-400 SAR Class 34-000 SAR Class 34-200 SAR Class 34-400 SAR Class 34-500 SAR Class 34-600 SAR Class 34-800 SAR Class 34-900 SAR Class 35-000 SAR Class 35-200 SAR Class 35-400 SAR Class 35-600 TFR Class 35-800 SAR Class 36-000 SAR Class 36-200 SAR Class 37-000 Spoornet Class 39-000 TFR Class 39-200 TFR Class 43-000 TFR Class 44-000 TFR Class 45-000
2' gauge Diesel-electric	SAR Class 91-000
Cape gauge Diesel-hydraulic	SAR Class 61-000
Cape gauge Electro-diesel	Spoornet Class 38-000