South African Classes 1-DE & 31-000
No. 31-028 (D727) at Bellville Depot, 31 October 2010
Type and origin Power type Diesel-electric Designer General Electric Builder General Electric Serial number 33507-33551 Model GE U12B Build date 1958 Total produced 45
Specifications Configuration: ​  • AAR B-B  • UIC Bo'Bo'  • Commonwealth Bo-Bo Gauge 3 ft 6 in (1,067 mm) Cape gauge Wheel diameter 915 mm (36.0 in) Wheelbase 10,118 mm (33 ft 2.3 in) ​  • Bogie 2,438 mm (8 ft 0 in) Pivot centres 7,680 mm (25 ft 2.4 in) Length: ​  • Over couplers 15,150 mm (49 ft 8.5 in) Width 2,780 mm (9 ft 1.4 in) Height 3,916 mm (12 ft 10.2 in) Axle load 18,900 kg (41,700 lb) Adhesive weight 75,600 kg (166,700 lb) Loco weight 75,600 kg (166,700 lb) max Fuel type Diesel Fuel capacity 3,000 litres (660 imp gal) Prime mover Cooper-Bessemer FVBL-8 RPM range 400-1,000 ​  • RPM low idle 400  • RPM idle 535  • Maximum RPM 1,000 Engine type 4 stroke V8 diesel Aspiration C-B ET13 turbocharger Generator DC 10 pole GE 5GT-581C3 Traction motors Four GE 5GE-761A4 DC 4 pole ​  • Rating 1 hour 600A  • Continuous 590A @ 16 km/h (9.9 mph) Cylinders V8 Gear ratio 94:17 MU working 3 maximum Loco brake 6-SLAV-1 with vigilance control Train brakes Westinghouse 6CDX4UC compressor/exhauster Air tank cap. 700 litres (150 imp gal) Compressor 0.039 m3/s (1.4 cu ft/s) Exhauster 0.155 m3/s (5.5 cu ft/s) Couplers AAR knuckle (SASKOP SS)
Performance figures Maximum speed 90 km/h (56 mph) Power output: ​  • Starting 985 kW (1,321 hp)  • Continuous 895 kW (1,200 hp) Tractive effort: ​  • Starting 181 kN (41,000 lbf) @ 25% adhesion  • Continuous 145 kN (33,000 lbf) @ 18 km/h (11 mph) Factor of adh.: ​  • Starting 25%  • Continuous 20% @ 18 km/h (11 mph) Brakeforce 65% ratio @ 345 kPa (50.0 psi)
Career Operators South African Railways Spoornet Sheltam Class Class 31-000 Number in class 45 Numbers 31-001 to 31-045 (D700-D744) Delivered June to July 1958 First run 1958

The South African Railways Class 31-000 of 1958 was a diesel-electric locomotive.

In June and July 1958, the South African Railways placed forty-five Class 1-DE General Electric type U12B diesel-electric locomotives in service. They were later reclassified to Class 31-000 and renumbered.^[1]

The South African Class 31-000 type GE U12B diesel-electric locomotive was designed for the South African Railways (SAR) and built by General Electric in 1958. They were the first diesel-electric road locomotives to enter SAR service in quantity.^[1][2]

Upon delivery, they were designated Class 1-DE and numbered in the range from D700 to D744 in the non-steam locomotive number range which had hitherto been used almost exclusively for electric locomotives, the exceptions being the pre-war experimental Class DS and Class DS1 diesel-electric locomotives. After the SAR adopted a new classification and numbering system for diesel-powered locomotives upon the arrival of the Class 32-000 in 1959, they were reclassified to Class 31-000 and renumbered in the range from 31-001 to 31-045.^[1][2]

The Class 31-000 was a high short hood locomotive. While the short hood end was usually considered as the front end, the cab was equipped with dual station controls to make it fully bidirectional.^[1]

They were placed in service at Germiston. One of their first duties was to take over the shunt duties at Milner Park from where complaints had been received from the tennis players at the club about the cinders being deposited on the all-weather courts. When originally ordered, it had been the intention to use them on shunting and block-load transfers on the Reef and as part of the program to eliminate steam traction from the new Johannesburg station, but their success in this service prompted a change in utilisation policy. In 1959 they were placed in mainline service working out of Johannesburg to Kroonstad and Bloemfontein in the Free State and to Volksrust on the mainline to Natal. They were very successful on mainline work and showed their ability to handle anything from goods workings to fast passenger trains like the Trans-Natal. They usually worked in pairs and longer lash-ups of up to four units were rarely seen.^{[3][4][5][6][7][8]}

The Class 31-000 had a huge impact on SAR motive power. In terms of speed and acceleration, they were superb and it didn't take long for the diesels to become a common sight on mainline working. Their unqualified success played a large part in the eventual demise of SAR steam traction.^[8][9]

By 1969 they were also used in goods working on the line from Krugersdorp via Magaliesburg and Swartruggens to Zeerust. By the 1980s they were finally relegated to the shunting and pickup service that they were originally intended for when new, working on the Reef and at some other major centres.^[2][10][11]

Of the original forty-five locomotives, forty survived into the Spoornet era in the 1990s. Now retired from Spoornet service, some still see service in private hands. Three of them, numbers 31-001 (D700), 31-005 (D704) and 31-038 (D737), were acquired by Sheltam for use at Rand Uranium near Randfontein and at Welkom. The first two were converted to low short hood locomotives and were still in service in 2014, while the third was used for spare parts.^[12][13]

Another private rail operator, RRL Grindrod, owns no. 31-009 (D708) as its no. RB-201, which was still employed at Welkom in 2014.^[13]

As of 2015, no. D706 (31-007) has been staged at Bloemfontein Locomotive Depot where a Locomotive Museum is being created to restore it and some other historically significant units, while no. D727 (31-028) is preserved at Bellville Loco Depot. ^[14]

The locomotives were delivered in a livery that displayed the colours of the South African flag, white on the upper half and blue on the lower half, separated by an orange stripe on the sides and orange whiskers on the ends. They had black running boards, red buffer beams and black cowcatchers. From 1960 this livery gradually began to be replaced by Gulf Red with yellow stripes.^[6][15]

The Class 31-000 builder's works numbers, renumbering and known disposition are listed in the table.^[12][13]

• 
  Sheltam no. 1201, ex SAR no. 31-005 (D704), 19 May 2010
• 
  No. 31-007 (D706) at Bellville Loco Depot, 10 January 2009

Media related to South African Class 31-000 at Wikimedia Commons