South African Class 31-000

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South African Classes 1-DE & 31-000
SAR Class 31-000 31-028 R.JPG
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
AAR wheel arr. B-B
UIC class 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)
 • 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 reservoir cap 700 litres (150 imp gal)
Compressor cap 0.039 m3/s (1.4 cu ft/s)
Exhauster cap 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
 • Continuous 20% @ 18 km/h (11 mph)
Loco brakeforce 65% ratio @ 345 kPa (50.0 psi)
Operators South African Railways
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]

Reclassification & renumbering[edit]

Upon delivery, they were classified as Class 1-DE and numbered in the range from D700 to D744, in the electric locomotive number range. When the SAR adopted a new classification and numbering system for electric and diesel-powered locomotives c. 1960, they were reclassified to Class 31-000 and renumbered in the range from 31-001 to 31-045.[1][2]


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


They were placed in service working out of Johannesburg to Kroonstad in the Free State and to Volksrust on the mainline to Natal. By the 1980s they were relegated to shunting and pickup service on the Reef and at some other major centres.[2]

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.[3][4]

Another private rail operator, RRL Grindrod, owns no. 31-009 (D708) as its no. RB-201, which is employed at Welkom.[4]

Works numbers[edit]

The Class 31-000 builder's works numbers, renumbering and disposition are listed in the table.[3]


Some of the liveries which were applied to Class 31-000 locomotives are illustrated below.


  1. ^ a b c d South African Railways Index and Diagrams Electric and Diesel Locomotives, 610 mm and 1065 mm Gauges, Ref LXD 14/1/100/20, 28 January 1975, as amended
  2. ^ a b c Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 137–138. ISBN 0869772112. 
  3. ^ a b 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, 45. 
  4. ^ a b SAR-L Yahoogroup message no. 47981 of 17 October 2014