South African Class 7E2, Series 1

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South African Class 7E2, Series 1
Class 7E2 Series 1 E7165.JPG
No. E7165 at Swartkops, Port Elizabeth, 22 April 2013
Type and origin
Power type Electric
Designer 50 c/s Group
Builder Union Carriage and Wagon
Model 50 c/s Group 7E2
Build date 1982
Total produced 25
Specifications
AAR wheel arr. C-C
UIC class Co'Co'
Gauge 3 ft 6 in (1,067 mm) Cape gauge
Wheel diameter 1,220 mm (48.0 in)
Wheelbase 13,460 mm (44 ft 1.9 in)
 • Bogie 4,060 mm (13 ft 3.8 in)
Pivot centres 10,200 mm (33 ft 5.6 in)
Panto shoes 10,200 mm (33 ft 5.6 in)
Length:
 • Over couplers 18,465 mm (60 ft 7.0 in)
 • Body 17,500 mm (57 ft 5.0 in)
Width 2,896 mm (9 ft 6.0 in)
Height:
 • Pantograph 4,200 mm (13 ft 9.4 in)
 • Body height 3,942 mm (12 ft 11.2 in)
Axle load 21,000 kg (46,000 lb)
Adhesive weight 125,800 kg (277,300 lb)
Loco weight 125,800 kg (277,300 lb)
Power supply Catenary
Current collection Pantographs
Traction motors Six MG-680
 • Rating 1 hour 515 kW (691 hp)
 • Continuous 500 kW (670 hp)
Gear ratio 20:117
Loco brake Air & Rheostatic
Train brakes Air & Vacuum
Couplers AAR knuckle
Performance figures
Maximum speed 88 km/h (55 mph)
Power output:
 • 1 hour 3,090 kW (4,140 hp)
 • Continuous 3,000 kW (4,000 hp)
Tractive effort:
 • Starting 450 kN (100,000 lbf)
 • 1 hour 319 kN (72,000 lbf)
 • Continuous 300 kN (67,000 lbf)
Career
Operators South African Railways
Spoornet
Transnet Freight Rail
Class Class 7E2
Power class 25 kV 50 Hz AC
Number in class 25
Numbers E7151-E7175
Delivered 1982
First run 1982

The South African Railways Class 7E2, Series 1 of 1982 is an electric locomotive.

In 1982, the South African Railways placed twenty-five Class 7E2, Series 1 electric locomotives with a Co-Co wheel arrangement in mainline service.[1]

Manufacturer[edit]

The 25 kV AC Class 7E2, Series 1 electric locomotive was designed for the South African Railways (SAR) by the 50 c/s Group, consisting of ACEC of Belgium, AEG-Telefunken and Siemens of Germany, Alsthom-Atlantique and Société MTE of France, and Brown Boveri of Switzerland.[2][3]

Builders’ plate on no. E7163

Twenty-five locomotives were built by Union Carriage and Wagon (UCW) in Nigel, Transvaal and delivered in 1982, numbered in the range from E7151 to E7175. Union Carriage and Wagon did not allocate builder’s numbers to the locomotives it built for the SAR, but used the SAR unit numbers for their record keeping.[1]

Orientation[edit]

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.[1]

SAR Class 7E2 Series 1 E7174 ID.JPG

In visual appearance, the Class 7E2, Series 1 can be distinguished from the Series 2 by the absence of the vertical grilles, on both sides just to the rear of the driver’s window on Series 2 locomotives. Both series have a large grille to the right of centre on the side opposite the roof access ladder side, near roof level on Series 1 locomotives and low down near sill level on Series 2. The three grilles in line, just to the rear of the side doors on Series 1 locomotives, were replaced with a single long grille on Series 2 locomotives. Like the Class 7E, some of the Class 7E2, Series 1 locomotives have distinctive "eyebrow" rainwater beadings above their cab windscreens, but these were added post-delivery and were not installed on all the locomotives.[1]

Features[edit]

Brakes[edit]

The control of traction and rheostatic braking on the Class 7E2, Series 1 is by stepless solid-state electronics. The electrical equipment was designed for high power factor operation, obtained by a sector control method.[3] Like the earlier South African Class 7E, these locomotives are equipped with thyristor technology from the 50 c/s Group.

Bogies[edit]

To reduce flange and rail wear, the bogies of the Class 7E2 have a shorter wheelbase than the Class 7E, 4,060 millimetres (13 feet 3.8 inches) instead of 4,400 millimetres (14 ft 5.2 in).[1][3]

Like the Class 7E, the Class 7E2 was built with sophisticated traction linkages on the bogies. Together with the locomotive's electronic wheel-slip detection system, these traction struts, mounted between the linkages on the bogies and the locomotive body and colloquially referred to as grasshopper legs, ensure the maximum transfer of power to the rails without causing wheel-slip, by reducing the adhesion of the leading bogie and increasing that of the trailing bogie by as much as 15% upon starting off.[3]

Pantographs[edit]

As on the Class 7E, the locomotive's pantograph contact shoe centres are directly above the bogie pivot centres. The reason is to reduce the possibility of pantograph hookups on catenary in sharp curves, such as in turnouts, as a result of sideways movement of the pantograph in relation to the overhead wire.[1]

Service[edit]

The Class 7E2, Series 1 was placed in service on the northern 25 kV routes, from Pyramid South, north of Pretoria, via Warmbad to Pietersburg and via Brits and Rustenburg to Thabazimbi. In 2012, as more of the new Class 19E locomotives became available, some were transferred to the Eastern Cape, where they augmented the existing Class 7E fleet, working out of Port Elizabeth via De Aar to Kimberley and Beaufort West.[4]

Illustration[edit]

The main picture shows no. E7153 in Spoornet blue livery with outline numbers. Other liveries which were applied to Class 7E2, Series 1 locomotives are illustrated below. The pictures also serve to illustrate the difference between the two sides of the locomotive.

References[edit]

  1. ^ a b c d e f 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" (PDF). The UCW Partnership. Archived from the original (PDF) on 12 October 2007. Retrieved 30 September 2010. 
  3. ^ a b c d Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 129–131. 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, 61.