South African Class Exp AC

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South African Class Exp AC
SAR Class ExpAC E1600 R.JPG
No. E1600 at Pyramid South, Pretoria, 7 May 2013
Type and origin
Power type Electric
Designer Union Carriage and Wagon
Builder Union Carriage and Wagon
Model UCW 6E1
Build date 1975
Total produced 100
Rebuilder Transwerk
Rebuild date 1978
Number rebuilt 1
UIC classification Bo-Bo
Gauge 3 ft 6 in (1,067 mm) Cape gauge
Bogies 3.430 m (11 ft 3.0 in) wheelbase
Wheel diameter 1,220 mm (48 in)
Wheelbase 11.279 m (37 ft 0.1 in)
Length 15.494 m (50 ft 10.0 in)
Width 2.896 m (9 ft 6.0 in)
Height 4.285 m (14 ft 0.7 in) pantograph down
Axle load 22,226 kg (21.9 long tons)
Locomotive weight 85,500 kg (84.1 long tons)
Current collection
Traction motors AEI 283AZ (four)
Transmission 18/67 Gear ratio
Performance figures
Maximum speed 113 km/h (70 mph)
Power output Per motor:
623 kW (835 hp) 1 hour
563 kW (755 hp) continuous
2,492 kW (3,342 hp) 1 hour
2,252 kW (3,020 hp) continuous
Tractive effort 330 kN (74,000 lbf) starting
218 kN (49,000 lbf) 1 hour
190 kN (43,000 lbf) continuous
Locomotive brake Air
Train brakes Air & Vacuum
Operator(s) South African Railways
Transnet Freight Rail
Class Class Exp AC
Power class 25 kV AC
Number in class 1
Number(s) E1600 [1]
First run 1978

The South African Class Experimental AC of 1978 is a South African electric locomotive from the South African Railways era.

In 1974 and 1975 the South African Railways placed one hundred Class 6E1, Series 5 locomotives with a Bo-Bo wheel arrangement in mainline service. In 1978 one of them, number E1600, was withdrawn from revenue service for use as an experimental 25 kV AC locomotive. It was rebuilt and reclassified to Class Experimental AC.[1]


The 3 kV DC Class 6E1, Series 5 electric locomotive was designed and built for the South African Railways (SAR) by Union Carriage and Wagon (UCW) in Nigel, Transvaal, with the electrical equipment supplied by General Electric Company (GEC). One hundred Series 5 locomotives were delivered by UCW in 1974 and 1975, numbered in the range from E1546 to E1645.[2]

To ensure the maximum transfer of power to the rails without causing wheel slip, the Class 6E1 was built with sophisticated traction links between the bogies and the frames and equipped with electronic wheel slip detection. These traction struts and linkages were to become a distinguishing feature of most subsequent South African electric locomotive models.[3]


These dual cab locomotives have a roof access ladder on one side only, just to the right of the cab access door. The roof access ladder end is marked as the no. 2 end. A passage along the centre of the locomotive connects the cabs.[1]

Test bed for 25 kV AC research[edit]

Of the 100 Series 5 units produced, number E1600 was permanently withdrawn from revenue service in 1978, rebuilt as a test-bed for use during 25 kV AC electrification and reclassified to the sole Class Experimental AC. It was used for testing to eliminate potential problems during the electrification of the four isolated 25 kV networks. These are:[1][3][4]

  • From Pyramid South to Pietersburg and via Rustenburg to Thabazimbi.
  • From Ermelo to Richards Bay.
  • From Port Elizabeth via Noupoort to De Aar and from there northward to Kimberley and southward to Beaufort West.
  • From East London to Springfontein.
Works plates on no. E1600

The locomotive’s single pantograph, electronic and electric equipment were manufactured by the 50 c/s Group, a consortium consisting of ACEC of Belgium, AEG-Telefunken and Siemens of Germany, Alsthom-Atlantique and Société MTE of France, and Brown Boveri of Switzerland. The same consortium also designed the 25 kV AC Class 7E locomotives that were placed in service on the four 25 kV networks.[3]

The vacuum circuit breaker was supplied by GEC. The original Class 6E1 AEI 283AZ traction motors by Associated Electrical Industries were retained and the locomotive used a thyristor-diode rectifier set for the traction motor DC power supply. The mechanical components were supplied by UCW.[1][3]

Apart from the inscriptions painted on the locomotive sides, the Class Experimental AC locomotive can be visually distinguished from Class 6E1 locomotives by the single pantograph on its no. 2 end instead of the usual two, as well as by the large grilles on the sides. The Class 6E1 has two large grilles to the right of centre on each side, while no. E1600 has only one such grille on the roof access ladder side and three on the opposite side.[3]

Sides illustrated[edit]

The main picture shows the roof access ladder or right side of no. E1600. In the picture below, showing the left side, the traction struts and linkages on the bogies were not installed since the locomotive was being refurbished at the time.

See also[edit]


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  1. ^ a b c d e South African Railways Index and Diagrams Electric and Diesel Locomotives, 610mm and 1065mm Gauges, Ref LXD 14/1/100/20, 28 January 1975, as amended
  2. ^ "UCW - Electric locomotives". The UCW Partnership. Archived from the original on 12 October 2007. Retrieved 30 September 2010. 
  3. ^ a b c d e Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 128–129, 136. ISBN 0869772112. 
  4. ^ Middleton, John N. (2002). Railways of Southern Africa Locomotive Guide - 2002 (as amended by Combined Amendment List 4, January 2009) (2nd, Dec 2002 ed.). Herts, England: Beyer-Garratt Publications. pp. 50–51, 60.