South African Class 7E1

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South African Class 7E1
SAR Class 7E1 E7111.JPG
No. E7111 at Vryheid, KwaZulu-Natal, 16 August 2007
Type and origin
Power type Electric
Designer Hitachi
Builder Hitachi & Dorbyl
Model Hitachi 7E1
Build date 1979-1981
Total produced 50
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 13,800 mm (45 ft 3.3 in)
 • Bogie 4,400 mm (14 ft 5.2 in)
Pivot centres 10,200 mm (33 ft 5.6 in)
Panto shoes 11,530 mm (37 ft 9.9 in)
Length:
 • Over couplers 18,430 mm (60 ft 5.6 in)
 • Over beams 17,480 mm (57 ft 4.2 in)
Width 2,906 mm (9 ft 6.4 in)
Height:
 • Pantograph 4,180 mm (13 ft 8.6 in)
 • Body height 3,941 mm (12 ft 11.2 in)
Axle load 21,000 kg (46,000 lb)
Adhesive weight 125,500 kg (276,700 lb)
Loco weight 125,500 kg (276,700 lb)
Power supply Catenary
Current collection Pantographs
Traction motors Six HS-1054-GR
 • Rating 1 hour 525 kW (704 hp)
 • Continuous 500 kW (670 hp)
Gear ratio 16:94
Loco brake Air & Rheostatic
Train brakes Air & Vacuum
Couplers AAR knuckle
Performance figures
Maximum speed 100 km/h (62 mph)
Power output:
 • 1 hour 3,150 kW (4,220 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 7E1
Power class 25 kV 50 Hz AC
Number in class 50
Numbers E7101-E7150
Delivered 1980-1981
First run 1980

The South African Railways Class 7E1 of 1980 is an electric locomotive.

In 1980 and 1981, the South African Railways placed fifty Class 7E1 electric locomotives with a Co-Co wheel arrangement in mainline service.[1]

Manufacturers[edit]

The 25 kV AC Class 7E1 electric locomotive was designed for the South African Railways (SAR) by Hitachi, while Dorbyl in South Africa supplied the mechanical components. The first six locomotives, numbered E7101 to E7106, were built by Hitachi in Japan in 1979, while forty-four more were built by Dorbyl in South Africa between 1979 and 1981, numbered in the range from E7107 to E7150.[2][3]

Like Union Carriage and Wagon, neither Hitachi nor Dorbyl allocated builder’s numbers to the Class 7E1 locomotives which it built for the SAR, but used the SAR unit numbers for their record keeping.[1]

Features[edit]

Appearance[edit]

SAR Class 7E1 E7133 ID.JPG

Since they were acquired solely for use on the Richards Bay coal line, where they would always work in multiple, they were built with single cabs. Following the Class 9E, which entered service in 1978, the Class 7E1 was the second single cab mainline electric locomotive to be acquired by the SAR. Until the Class 9E was introduced in 1978, all South African mainline electric locomotives were dual cab units.[1]

The two sides of the Class 7E1 are sufficiently different in appearance that, when coupled end to end, a pair of them appears at first glance to be two different locomotive types. The left side is smooth, while the right has several large grilles.[1]

Pantographs[edit]

The locomotive's pantograph placement is unusual, in not being equidistant from the locomotive ends. The contact shoe centre of the no. 1 end pantograph is 5,280 millimetres (17 feet 3.9 inches) from the longitudinal centre of the locomotive, while that of the no. 2 end pantograph is 6,250 millimetres (20 feet 6.1 inches) from the centre.[1]

Brakes[edit]

Control of traction and rheostatic braking on the Class 7E1 is by stepless solid-state electronics. The electrical equipment was designed for high power factor operation, obtained by the switching in of power-factor correction capacitors.[2]

Unlike the Classes 7E and 7E2, where thyristors are used, these locomotives use silicon-diode rectifiers.[4]

In the period from the early 1990s until about 2007, various modifications to improve downhill braking capacity were done to the Coalink line's Hitachi-designed locomotives. The first set of upgrades were done on the fifty Class 7E1 locomotives. They retained their Class 7E1 classification after modification.[2][3]

Bogies[edit]

Like the Class 6E1 and Class 7E, the Class 7E1 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.[2]

Service[edit]

The Class 7E1 was placed in service on the 25 kV AC Ermelo-Richards Bay Coalink line, where most of them still work.[2]

Illustration[edit]

The main picture shows no. E7111’s right side and no. 2 end, in SAR Gulf Red and yellow whiskers livery. The cab end, left side and other liveries which were applied to the Class 7E1 are illustrated below.

References[edit]

  1. ^ a b c d e 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. ^ a b c d e Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 129–131. 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. 51, 61. 
  4. ^ Jane's Train Recognition Guide