South African Class 91-000

South African Class 91-000

300px No. 91-003 and 91-009 on the limestone train from Loerie PPC to New Brighton

Type and origin Power type Diesel-electric Designer General Electric Builder General Electric Serial number 38603-38622 Model GE UM6B Build date 1973 Total produced 20

Specifications AAR wheel arr B-B UIC class Bo'Bo' Gauge 2 ft (610 mm) narrow gauge Bogies Narrow gauge wheelbase: 2,108 mm (6 ft 10.99 in) Bigfoot wheelbase: 2,082 mm (6 ft 9.97 in) Wheel diameter Narrow gauge: 838 mm (32.99 in) Bigfoot: 915 mm (36.02 in) Wheelbase Narrow gauge: 7,290 mm (23 ft 11.01 in) Bigfoot: 7,314 mm (23 ft 11.95 in) Length 10,580 mm (34 ft 8.54 in) Width 2,564 mm (8 ft 4.94 in) Height 3,632 mm (11 ft 10.99 in) Frame 5,232 mm (17 ft 1.98 in) between bogie pivot centres Axle load 12,000 kg (26,000 lb) Loco weight 44,000 kg (97,000 lb) average 48,000 kg (106,000 lb) permissible Fuel type Fuel oil Fuel capacity 1,600 litres (350 imp gal; 420 US gal) Prime mover Caterpillar D-379 RPM range 650 rpm idle 1,365 rpm maximum Engine type 4 stroke diesel Aspiration Schwitzer 4ME 455 turbocharger Generator DC 6 pole GE 5GT-601C1 Traction motors Narrow gauge: Four GE 5GE-778AI DC 4 pole * 410A 1 hour * 395A at 14 km/h (8.7 mph) Bigfoot: Two GE 5GE-761-A13 DC 4 pole * 333A 1 hour * 328A continuous at 15 km/h (9.3 mph) Cylinders V8 Transmission Double reduction 13,68/1 gear ratio MU working 3 maximum Loco brake 28-LV-1 Dynamic brake peak effort: 85 kN (19,000 lbf) at 14 km/h (8.7 mph) Train brakes 850 litres (220 US gal) main reservoir Compressor capacity at idle: 0.03 m3/s (1.1 cu ft/s) Exhauster capacity at idle: 0.072 m3/s (2.5 cu ft/s) Safety systems Vigilance control

Performance figures Maximum speed 50 km/h (31 mph) Power output 520 kW (700 hp) starting 480 kW (640 hp) continuous Tractive effort 108 kN (24,000 lbf) starting 86 kN (19,000 lbf) at 15 km/h (9.3 mph) Factor of adh 25% starting 20% continuous Loco brakeforce 60% ratio at 345 kPa (50 psi) brake cylinder pressure

Career Operators South African Railways Spoornet Transnet Freight Rail RRL Grindrod Class Class 91-000 Number in class 20 Numbers 91-001 to 91-020 Delivered 1973 First run 1973

The South African Railways Class 91-000 of 1973 is a narrow gauge diesel-electric locomotive from the South African Railways era.

Between September and December 1973 the South African Railways placed twenty Class 91-000 General Electric type UM6B diesel-electric locomotives in service on its narrow gauge Avontuur Railway line between Port Elizabeth in the Eastern Cape and Avontuur in the Western Cape. Some of them later also worked on the Alfred County Railway line out of Port Shepstone in KwaZulu-Natal.

Manufacturer

The Class 91-000 GE type UM6B diesel-electric locomotive was designed and built for the South African Railways (SAR) by General Electric (GE) in Erie, Pennsylvania. Twenty locomotives were delivered between September and December 1973, numbered in the range from 91-001 to 91-020. It was designed for 2 ft (610 mm) narrow gauge and is the largest two foot gauge diesel-electric locomotive in the world at an average weight of 44,000 kilograms (43.3 long tons; 48.5 short tons).

File:Class 91-000 91-002 BPR.JPG

Works plate on no. 91-002

The usual practice was to have locomotive builder’s works plates attached to the locomotive’s frame below the cab windows. The Class 91-000 locomotives, however, had their works plates mounted on each side of the long hood. With the exception of numbers 91-001 (GE 38604), 91-002 (GE 38603), 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.

Characteristics

As a result of the severe clearance problems presented by the 2 ft (610 mm) gauge, it was not possible to follow the usual practice of axle-hung traction motors. Special bogies had to be designed with the traction motors mounted between the axles, with one traction motor on each side of each bogie.

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 upon braking and snatching upon 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 or SA3 coupler that eventually replaced the old Norwegian Hook type coupler on South African narrow gauge rolling stock.

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 diesel-electric locomotive type to have operated on South Africa’s narrow gauge lines.

Service

South African Railways

These locomotives served nearly exclusively on the Langkloof line, but between 1992 and December 2003 a few of them also worked on the Alfred County Railway (ACR) narrow gauge line out of Port Shepstone. The locomotives that were transferred to Natal travelled all the way from Port Elizabeth under their own power on what became known as Bigfoot bogies, which were in fact 3 ft 6 in (1,067 mm) Cape gauge Class 36-000 GE type SG10B 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.

Over the years since the Class 91-000 was commissioned, the demand for rail services declined steadily on both the ACR and the Langkloof lines. 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. When the quarry that fed Loerie station by cableway was closed, however, the fate of the narrow gauge line was virtually sealed.

Despite this, in the narrow gauge line’s centenary year in 2003, Spoornet still stated its commitment to keep 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) branchline from Loerie further up the Gamtoos valley to assist farmers who had difficulty moving their produce.

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.

At least one Class 91-000 locomotive, no. 91-010, was still in service with TFR by 2013. It was mounted on Bigfoot bogies of which only one was equipped with traction motors, and equipped with AAR knuckle couplers for use as a shunting locomotive at the Swartkops electric locomotive depot in Port Elizabeth. The rest of the fleet that were still on the TFR roster were standing idle, staged at the narrow gauge depot at Humewood Road in Port Elizabeth.

Industrial service

Five locomotives were sold to RRL Grindrod, a joint venture between Solethu Investments, a South African Black Economic Empowerment (BEE) rail logistics company, and Grindrod Limited, a shipping and logistics group, for use at Welkom in the Free State to haul mine hoppers. Four of them were renumbered in the range from RRL 91-01 to 91-04 and their original narrow gauge bogies were cut in half and widened to 3 ft 6 in (1,067 mm) Cape gauge. The fifth was the accident-damaged no. 91-009, which was completely rebuilt as a 700hp Caterpillar engine-generator.

Three more locomotives were sold on auction on 11 July 2013. These were purchased by a Port Elizabeth scrap merchant for rebuilding and resale.

Works numbers

The Class 91-000 builder’s works numbers and their disposal are shown in the table.

Class 91-000, GE type UM6B

Loco no.	Works no.	Disposal
91-001	38604
91-002	38603
91-003	38605	RRL 91-03
91-004	38606
91-005	38607
91-006	38608
91-007	38609
91-008	38610
91-009	38611	RRL rebuilt as gen-set
91-010	38612
91-011	38613	Sold auction 11 Jul 2013
91-012	38614	RRL 91-01
91-013	38615	Sold auction 11 Jul 2013
91-014	38616	Scrapped
91-015	38617
91-016	38619	RRL 91-04
91-017	38618	RRL 91-02
91-018	38620	Sold auction 11 Jul 2013
91-019	38621
91-020	38622

Illustration

All the Class 91-000 locomotives were delivered in the SAR Gulf Red and whiskers livery. The main picture shows numbers 91-003 and 91-009 in that livery, on the limestone train from Loerie PPC to New Brighton on 8 April 1985. They were later all repainted in the Spoornet orange livery. Only one, no. 91-001, was again repainted in the Spoornet blue livery with outline numbers.

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  No. 91-006 at Humansdorp station, 18 October 2009

• Class 91-001 at Humewood.jpg

  No. 91-001 at Humewood Road, Port Elizabeth, 20 December 2006

• Class 91-000 91-010.JPG

  Bigfoot no. 91-010 in shunting service at Swartkops, Port Elizabeth, 21 April 2013

• SAR Class 91-000 91-003 BF.jpg

  No. 91-003 being equipped with Bigfoot bogies, Port Shepstone, 8 April 2004

• SAR Class 91-000 91-018 Van Stadens.jpg

  No. 91-018 crossing the Van Stadens River with the Apple Express, 6 April 2002