South African Class 7E4

The Spoornet Class 7E4 of 2001 is a South African electric locomotive.

In 1983 and 1984, the South African Railways placed sixty Class 7E3, Series 1 electric locomotives with a Co-Co wheel arrangement in mainline service. These were followed by another twenty-five Class 7E3, Series 2 locomotives in 1984 and 1985. Beginning in 2000, Spoornet rebuilt seventeen of these dual-cab locomotives to single-cab locomotives and reclassified them to Class 7E4.^[1]

Manufacturers

The 25 kV AC Class 7E3 electric locomotives were designed for the South African Railways (SAR) by Hitachi and built in South Africa by Dorbyl, who also supplied the mechanical components.^[2][3]

Sixty Series 1 locomotives were delivered by Dorbyl in 1983 and 1984, numbered in the range from E7216 to E7275, and twenty-five Series 2 locomotives in 1984 and 1985, numbered in the range from E7276 to E7300. Like Union Carriage and Wagon, Dorbyl did not allocate builder’s numbers to the locomotives it built for the SAR, but used the SAR unit numbers for their record keeping.^[2]

Modification and reclassification

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 was done on the fifty Class 7E1 locomotives.^[1]

Beginning in 2000, seventeen Class 7E3 locomotives, sixteen Series 1, numbered in the range from E7260 to E7275, and one Series 2, no. E7276, underwent significant modifications. This included the installation of Hitachi micro-processor controls with improved rheostatic brakes, auxiliary inverters designed and built by Fuji Electric, Thelma and Cutler-Hammer rheostat grids, fans by Donkin Fans in Port Elizabeth, and conversion from double-cab to single-cab, since the no. 2 end cab space was required for some of the new equipment which was installed. These single-cab locomotives were reclassified to Class 7E4 and the first of them entered service early in 2001.^[1][4]

Features

Appearance

The two sides of the locomotive are sufficiently different in appearance that a pair of them, coupled end to end, appears at first glance to be two different locomotive types. The left side is smooth, while the right side has several large grilles.^[2]

Pantographs

The locomotive's pantograph placement is unusual, in not being equidistant from the locomotive ends. The contact shoe centre of the front pantograph is 6,155 millimetres (20 feet 2.32 inches) from the longitudinal centre of the locomotive, while that of the rear pantograph is 5,920 millimetres (19 feet 5.07 inches) from the longitudinal centre.^[2]

Brakes

Control of traction and rheostatic braking on the Class 7E4 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.^[3]

Unlike the Classes 7E and 7E2 Series 1 and 2, where thyristors are used, these locomotives feature silicon-diode rectifiers.^[5]

Bogies

Like the Class 7E, the Class 7E4 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]

Service

Since 1978, 25 kV AC was introduced on all new mainline electrification projects bar one, the exception being the Orex iron ore line from Sishen to Saldanha, where 50 kV AC is used. The Class 7E4 locomotives all serve on the 25 kV AC Coalink line from Ermelo via Vryheid to the Richards Bay Coal Terminal.^[1][3]

The Blue Train

In the SAR and Spoornet eras, when the official liveries were Gulf Red and yellow whiskers for the SAR, and initially orange and later maroon for Spoornet, many selected electric locomotives and some diesel-electrics were painted blue for use with the Blue Train, but without altering the layout of the various paint schemes. Blue Train locomotives were therefore blue with yellow whiskers in the SAR era, blue with the Spoornet logo and the name "SPOORNET" in Spoornet’s orange era, and blue with the Spoornet logo, but without the name "SPOORNET", in Spoornet’s maroon era. Later, in Spoornet’s blue era, there was no need for a separate Blue Train livery, while in the Transnet Freight Rail (TFR) era, one Class 14E and the surviving Class 14E1 electric locomotives were eventually repainted in blue during 2012 for use with the Blue Train.^[1][6][7]

While it is doubtful that the intention was to have a Class 7E4 in blue train livery for blue train hauling on the Richards Bay line, the ones observed, numbers E7272 and E7275, were nevertheless painted in Spoornet’s maroon era Blue Train livery after being rebuilt, possibly to make them easier to identify at a glance.^[7]

Illustration

• 
  No. E7275 at Vryheid, 16 August 2007
• 
  No. E7272 at Nsezi near Richards Bay, 8 December 2013

References

Wikimedia Commons has media related to South African Class 7E4.

Locomotives of South Africa
Steam	7' ¼" gauge East London 0-4-0VB Table Bay 0-4-0ST Table Bay 0-4-0T Table Bay 0-4-0WT 4' 8½" gauge Cape 0-4-0T Blackie Cape 0-4-2 Cape 2-4-0T CGR 0-4-0ST Aid Natal 0-4-0ST Durban Natal 0-4-0WT Natal Natal 4-4-0T Perseverance 3' 6" gauge Tank engines CGR 0-4-0ST 1873 CGR 0-4-0ST 1874 CGR 0-4-0ST 1881 CGR 0-4-0ST 1881 Coffee Pot CGR 0-6-0ST CGR 0-6-0T CGR 2-6-0ST 1900 CGR 2-6-0ST 1902 CGR 1st Class 0-4-0ST 1875 CGR 1st Class 0-4-0ST 1876 CGR 1st Class 2-6-0ST CGR 1st Class 4-4-0T CGR 2nd Class 4-4-0T CGR 3rd Class 2-6-0T CGR Railmotor CSAR Class C CSAR Class E CSAR Rack 4-6-4RT CSAR Railmotor Durban's Congella Durban's Edward Innes Durban's John Milne Durban's Sir Albert Port Elizabeth 0-4-0ST Kowie Railway 0-6-0T Kowie Railway 4-4-0T Metropolitan & Suburban 4-6-2T NGR 2-6-0T Durban & Pietermaritzburg NGR Class I 2-6-2T NGR Class K 0-4-0ST NGR Class K 0-6-0ST NGR Class K 2-6-0T NZASM 10 Tonner NZASM 13 Tonner NZASM 14 Tonner NZASM 18 Tonner NZASM 19 Tonner NZASM 32 Tonner NZASM 40 Tonner PPR 26 Tonner PPR 35 Tonner Portuguese SAR Class A SAR Class B SAR Class C SAR Class C1 SAR Class C2 SAR Class D SAR Class E SAR Class F SAR Class G SAR Class H SAR Class H1 SAR Class H2 SAR Class J SAR Class K SAR Railmotor SAR Dock 0-4-0ST SAR Dock 0-4-0T SWA 2-8-0T 3' 6" gauge Tender engines CGR 1st Class 2-6-0 1876 BP CGR 1st Class 2-6-0 1876 Kitson CGR 1st Class 2-6-0 1879 CGR 1st Class 2-6-0 1891 CGR 1st Class 4-4-0 CGR 1st Class 4-4-0TT CGR 2nd Class 2-6-2TT CGR 3rd Class 4-4-0 1883 CGR 3rd Class 4-4-0 1884 CGR 3rd Class 4-4-0 1889 CGR 3rd Class 4-4-0 1898 CGR 3rd Class 4-4-0 1901 CGR 3rd Class 4-4-0 1903 CGR 4th Class 4-4-2 CGR 4th Class 4-6-0TT 1880 CGR 4th Class 4-6-0TT 1882 CGR 4th Class 4-6-0TT 1882 Joy CGR 4th Class 4-6-0TT 1884 CGR 5th Class 4-6-0 1890 CGR 5th Class 4-6-0 1891 NGR Havelock NGR Class I SAR Class Exp 1 SAR Class Exp 2 SAR Class Exp 3 SAR Class Exp 4 SAR Class Exp 5 SAR Class Exp 6 SAR Class S SAR Class S1 SAR Class S2 SAR Class 1 SAR Class 1A SAR Class 1B SAR Class 2 SAR Class 2C SAR Class 3 SAR Class 3A SAR Class 3B SAR Class 4 SAR Class 4A SAR Class 5 SAR Class 5A SAR Class 5B SAR Class 6 SAR Class 6A SAR Class 6B SAR Class 6C SAR Class 6D SAR Class 6E SAR Class 6F SAR Class 6G SAR Class 6H SAR Class 6J SAR Class 6K SAR Class 6L SAR Class 6Y SAR Class 6Z SAR Class 7 SAR Class 7A SAR Class 7B SAR Class 7C SAR Class 7D SAR Class 7E SAR Class 7F SAR Class 8 SAR Class 8A SAR Class 8B SAR Class 8C SAR Class 8D SAR Class 8E SAR Class 8F SAR Class 8R SAR Class 8X SAR Class 8Y SAR Class 8Z SAR Class 9 SAR Class 10 SAR Class 10A SAR Class 10B SAR Class 10C SAR Class 10D SAR Class 11 SAR Class 12 SAR Class 12A SAR Class 12B SAR Class 13 SAR Class 14 SAR Class 14A SAR Class 14B SAR Class 14C 1st SAR Class 14C 2nd SAR Class 14C 3rd SAR Class 14C 4th SAR Class 15 SAR Class 15A SAR Class 15B SAR Class 15C SAR Class 15CA SAR Class 15E SAR Class 15F SAR Class 16 SAR Class 16A SAR Class 16B SAR Class 16C SAR Class 16D SAR Class 16DA 1928 SAR Class 16DA 1930 SAR Class 16E SAR Class 17 SAR Class 18 SAR Class 19 SAR Class 19A SAR Class 19B SAR Class 19C SAR Class 19D SAR Class 20 SAR Class 21 SAR Class 23 SAR Class 24 SAR Class 25 SAR Class 25NC SAR Class 26 SAR Katanga SWA 2-8-0 3' 6" gauge Articulated engines CGR Fairlie CGR Kitson-Meyer SAR Class FC SAR Class FD SAR Class GA SAR Class GB SAR Class GC SAR Class GCA SAR Class GD SAR Class GDA SAR Class GE SAR Class GEA SAR Class GF SAR Class GG SAR Class GH SAR Class GK SAR Class GL SAR Class GM SAR Class GMA SAR Class GO SAR Class HF SAR Class KM SAR Class MA SAR Class MB SAR Class MC SAR Class MC1 SAR Class MD SAR Class ME SAR Class MF SAR Class MG SAR Class MH SAR Class MJ SAR Class MJ1 SAR Class U 2' 6" gauge Cape Copper John King & Miner Cape Copper Britannia Cape Copper Caledonia Cape Copper Clara Cape Copper Condenser Cape Copper Scotia Namaqua Copper Pioneer Walvis Bay 2-4-2T Hope 2' & 600mm gauges ACR Class NG-G16A CGR NG 0-4-0T CGR NG 0-6-0T CGR NG 4-6-2T CGR Type A 2-6-4T CGR Type C 0-4-0T NGR Class N 4-6-2T SAR Dutton SAR NG 0-4-0T SAR Class NG1 SAR Class NG2 SAR Class NG3 SAR Class NG4 SAR Class NG5 SAR Class NG6 SAR Class NG7 SAR Class NG8 SAR Class NG9 SAR Class NG10 SAR Class NG-G11 SAR Class NG-G12 SAR Class NG-G13 SAR Class NG-G14 SAR Class NG15 SAR Class NG-G16 SWA Class Ha SWA Class Hb SWA Class Hc SWA Class Hd SWA Jung SWA Zwillinge
Electric	Amcoal Class E38 SAR Class ES SAR Class ES1 SAR Class Exp-AC SAR Class 1E SAR Class 2E SAR Class 3E SAR Class 4E SAR Class 5E s1 SAR Class 5E s2 SAR Class 5E s3 SAR Class 5E1 s1 SAR Class 5E1 s2 SAR Class 5E1 s3 SAR Class 5E1 s4 SAR Class 5E1 s5 SAR Class 6E SAR Class 6E1 s1 SAR Class 6E1 s2 SAR Class 6E1 s3 SAR Class 6E1 s4 SAR Class 6E1 s5 SAR Class 6E1 s6 SAR Class 6E1 s7 SAR Class 6E1 s8 SAR Class 6E1 s9 SAR Class 6E1 s10 SAR Class 6E1 s11 SAR Class 7E SAR Class 7E1 SAR Class 7E2 s1 SAR Class 7E2 s2 SAR Class 7E3 s1 SAR Class 7E3 s2 Spoornet Class 7E4 SAR Class 8E SAR Class 9E s1 SAR Class 9E s2 SAR Class 10E SAR Class 10E1 s1 Spoornet Class 10E1 s2 SAR Class 10E2 SAR Class 11E SAR Class 12E Spoornet Class 14E Spoornet Class 14E1 TFR Class 15E Spoornet Class 16E Spoornet Class 17E Spoornet Class 18E s1 TFR Class 18E s2 TFR Class 19E TFR Class 20E TFR Class 21E TFR Class 22E
Gas-electric	SAR Gas-electric
Diesel	3' 6" gauge Diesel-electric PRASA Class Afro 4000 SAR Class DS SAR Class DS1 SAR Class 31-000 SAR Class 32-000 SAR Class 32-200 SAR Class 33-000 SAR Class 33-200 SAR Class 33-400 SAR Class 34-000 SAR Class 34-200 SAR Class 34-400 SAR Class 34-500 SAR Class 34-600 SAR Class 34-800 SAR Class 34-900 SAR Class 35-000 SAR Class 35-200 SAR Class 35-400 SAR Class 35-600 TFR Class 35-800 SAR Class 36-000 SAR Class 36-200 SAR Class 37-000 Spoornet Class 39-000 TFR Class 39-200 TFR Class 43-000 TFR Class 44-000 2' gauge Diesel-electric SAR Class 91-000 3' 6" gauge Diesel-hydraulic SAR Class 61-000 3' 6" gauge Electro-diesel Spoornet Class 38-000
List of South African locomotive classes South African locomotive numbering and classification