South African Class 91-000

Between September and December 1973 the South African Railways placed twenty Class 91-000 GE UM6B diesel-electric locomotives in service on its narrow gauge Langkloof apple train line between Humewood Road in Port Elizabeth in the Eastern Cape and Avontuur in the Western Cape.^[2][3]

Manufacturer

The Class 91-000 type GE UM6B diesel-electric locomotive was designed and built for the South African Railways (SAR) by General Electric (GE) in Erie, Pennsylvania, and imported. Twenty loomotives were delivered between September and December 1973, numbered 91-001 to 91-020. It was designed for 610 millimetres (2 feet) gauge (Cape narrow gauge) and is the largest two foot gauge diesel-electric locomotive in the world, weighing in at 44,000 kilograms (43.3 long tons) average.^[4]

The usual practice is to have builder’s works plates attached to the locomotive’s frame below the cab windows. Class 91-000 locomotives, however, had their works plates mounted on each side of the long hood. With the exception of numbers 91-016 (GE 38619) and 91-017 (GE 38618), the Class 91-000 works numbers are in sequence with their running numbers. It is very likely, however, that this was the result of body panels being swapped between locomotives during overhauls.^[1]

Characteristics

As a result of the severe clearance problems presented by the two foot gauge, it was not possible to follow the usual practice of axle-hung traction motors and special bogies had to be designed with the traction motors mounted between the axles.^[3]

The locomotives are both air and dynamically braked, while a "lag control" was incorporated into the train’s brake pipes to prevent bunching of the wagons on braking and snatching on restarting. This, combined with the cabling required for multi-unit control, resulted in altogether seven cable connections between consisted units. The Class 91-000 also introduced the new Willison coupler that eventually replaced the old "Norwegian Hook" type coupler on the narrow gauge.^[3]

End of the steam era

The Class 91-000 replaced the ageing Class NG G13 and NG G16 Garratts and Class NG15 2-8-2 "Kalahari" steam locomotives that had been working the Langkloof narrow gauge line until then. It is the only South African diesel-electric locomotive type to have operated on South Africa’s narrow gauge lines.^[3]

Service

South African Railways

These locomotives served nearly exclusively on the Langkloof line, but between 1992 and December 2003 a few also worked on the Alfred County Railway (ACR) out of Port Shepstone. The locomotives that were transferred to Natal travelled all the way from Port Elizabeth under their own power on what were known as "Bigfoot bogies", which were in fact Class 36-000 Cape gauge bogies. These Bigfoot bogies were also used under the Class 91-000 locomotives whenever they had to be exchanged for maintenance purposes, sometimes running under their own power, sometimes hauled dead.^[1]

Over the years since the Class 91-000 was commissioned, the demand for rail services declined steadily on both the ACR and the Langkloof apple line. Still, even though road transport had triumphed over rail transport in respect of fruit traffic from the Langkloof by the 1980s, the eastern part of the line remained busy for some years hauling limestone from Loerie, until the quarry that fed Loerie station by cableway was closed.^[5]

Despite this, in the narrow gauge line’s centenary year in 2003, Spoornet still stated its commitment to keeping the line in service by investing in infrastructure and technology. As recently as September 2005 there was even talk of extending the 107 kilometres (66 miles) branch from Loerie further up the Gamtoos valley to assist farmers who had difficulty moving their produce.^[6]

By 2009, however, Transnet Freight Rail (TFR) had decided that narrow-gauge railway operations were no longer in its "core line of business" and started culling the herd by putting some of the Class 91-000 locomotives up for auction. Of the twenty locomotives built, eighteen were still in operation by 2009, two having been withdrawn after accident damage.^[1]

Industrial service

Four were sold to RRL Grindrod, a joint venture between Solethu Investments, a rail logistics company, and Grindrod Limited, a shipping and logistics group, for use at Welkom in the Free State to haul mine hoppers. They were renumbered RRL 91-01 to 91-04 and their original 610 millimetres (2 feet) narrow gauge bogies were cut in half and widened to 1,067 millimetres (3 feet 6 inches) Cape gauge.^[7][8][9]

Gallery

See also

• Diesel-electric locomotive numbering and classification
• Diesel-electric locomotive
• Avontuur Railway
• Alfred County Railway
• List of South African locomotive classes
• Two foot gauge railways in South Africa

References

1. ^ ^{a b c d} 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. 38-39, 45. 
2. ^ ^{a b} 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
3. ^ ^{a b c d} Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. p. 144. ISBN 0869772112. 
4. ^ Class 91-000 page from the SAR Index and Diagrams of Electric and Diesel Locomotives, Ref LXD 14/1/100/20, Issued 28/1/75
5. ^ Revamping the Apple Express
6. ^ 100 Years of Being at the Heart of It All, Spoornet brochure, Circa 2003
7. ^ Langkloof narrow-gauge
8. ^ Class 91 Diesels in the OFS
9. ^ Transnet Freight Rail auction results