South African Class 7E2, Series 2

South African Class 7E2, Series 2

300px No. E7215 at Pyramid South, Pretoria, 6 October 2009

Type and origin Power type Electric Designer 50 c/s Group Builder Union Carriage and Wagon Model 50 c/s Group 7E2 Build date 1983 Total produced 40

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) Length:  • Over couplers 18,465 mm (60 ft 7.0 in)  • Body 17,500 mm (57 ft 5.0 in)  • Pivot centres 10,200 mm (33 ft 5.6 in)  • Panto shoes 10,200 mm (33 ft 5.6 in) Width 2,896 mm (9 ft 6.0 in) Height:  • Pantograph 4,190 mm (13 ft 9.0 in)  • Body height 3,942 mm (12 ft 11.2 in) Axle load 21,000 kg (46,000 lb) Adhesive weight 124,000 kg (273,000 lb) Loco weight 124,000 kg (273,000 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 PRASA Class Class 7E2 Power class 25 kV 50 Hz AC Number in class 40 Numbers E7176-E7215 Delivered 1983 First run 1983

The South African Railways Class 7E2, Series 2 of 1983 is an electric locomotive.

In 1983, the South African Railways placed forty Class 7E2, Series 2 electric locomotives with a Co-Co wheel arrangement in mainline service.

Manufacturer

File:Plate UCW 7E2 (E7204).JPG

Builders’ plate, no. E7204

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

It was built by Union Carriage and Wagon (UCW) in Nigel, Transvaal, who delivered forty locomotives in 1983, numbered in the range from E7176 to E7215. UCW did not allocate builder’s numbers to the locomotives which it built for the SAR, but used the SAR unit numbers for their record keeping.

Orientation

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 designated the no. 2 end.

File:SAR Class 7E2 Series 2 E7204 ID.JPG

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In visual appearance, the Series 2 locomotives can be distinguished from the Series 1 by the vertical grilles just to the rear of the driver’s window, on both sides on the Series 2 locomotives, absent on Series 1. 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 2 locomotives have distinctive "eyebrow" rainwater beadings above their cab windscreens, but these were added post-delivery and were not installed on all the units.

Features

Brakes

Control of traction and rheostatic braking on the Class 7E2, Series 2 is by stepless solid-state electronics. The electrical equipment was designed for high power factor operation, obtained by a sector control method. Like the earlier Classes 7E and 7E2, Series 1, these locomotives were equipped with thyristor technology from the 50 ^c/s Group.

Bogies

To reduce flange and rail wear, the bogies of both series of the Class 7E2 have a shorter wheelbase than the Class 7E, 4,060 millimetres (13 feet 3.8 inches) instead of .

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.

Pantographs

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.

Service

The Class 7E2, Series 2 was placed in service on the northern 25 kV AC routes, which stretch from Pyramid South, just north of Pretoria, via Warmbad to Pietersburg and via Brits and Rustenburg to Thabazimbi, where they still serve.

Illustration

The main picture shows no. E7215 in its original SAR Gulf Red and yellow whiskers livery. Other liveries which were applied to Class 7E2, Series 2 locomotives, are illustrated below.

• SAR Class 7E2 Series 2 E7202.JPG

  No. E7202 in Spoornet orange livery at Pyramid South, 6 October 2009

• SAR Class 7E2 Series 2 E7182.JPG

  No. E7182 in Spoornet maroon at Pyramid North, 6 October 2009

• SAR Class 7E2 Series 2 E7200.JPG

  No. E7200 in Spoornet blue with outline numbers at Pyramid South, 6 October 2009

• Class 7E2 E7206.jpg

  No. E7206 in Transnet Freight Rail livery at Pyramid South, 27 September 2015

• Class 7E2 Series 2 E7201.JPG

  No. E7201 in PRASA's Shosholoza Meyl livery at Pyramid South, 7 May 2013