South African Class 4E
|South African Class 4E|
No. E238 at rest at the Salt River Depot, Cape Town, 7 January 1966
|Designer||General Electric Company|
|Builder||North British Locomotive Company|
|Serial number||26859-26898 |
|UIC classification||1Co+Co1 interlinked bogies|
|Gauge||3 ft 6 in (1,067 mm) Cape gauge|
|Bogies||6.833 m (22 ft 5 in) wheelbase|
|792 mm (31.2 in)|
|Wheel diameter||1,295 mm (51 in)|
|Wheelbase||18.390 m (60 ft 4 in)|
|Length||21.844 m (71 ft 8 in)|
|Height||3.924 m (12 ft 10.5 in) pantographs down|
|Axle load||13,209 kg (13 long tons) per pony axle
21,845 kg (21.5 long tons) per traction axle
|Locomotive weight||157,488 kg (155 long tons)|
|Traction motors||Six GEC WT580|
|Transmission||21/75 Gear ratio|
|Top speed||97 km/h (60 mph)|
|Power output||Per motor:
377 kW (506 hp) 1 hour
313 kW (420 hp) continuous
2,262 kW (3,033 hp) 1 hour
1,878 kW (2,518 hp) continuous
|Tractive effort||322 kN (72,000 lbf) starting
185 kN (42,000 lbf) 1 hour
141 kN (32,000 lbf) continuous
|Train brakes||Air & Vacuum|
|Railroad(s)||South African Railways|
|Power class||3 kV DC|
|Number in class||40|
|Nicknames||Groen Mamba (Green Mamba)
Groot Mamba (Large Mamba)
Between 1952 and 1954 the South African Railways placed forty Class 4E electric locomotives with a 1Co+Co1 wheel arrangement in service on the mainline from Cape Town across the Hex River rail pass to Touws River in the Karoo.
The 3 kV DC Class 4E electric locomotive was designed for the South African Railways (SAR) by the General Electric Company (GEC) and built by the North British Locomotive Company (NBL) between 1952 and 1953. They were delivered between 1952 and 1954 and were numbered in the range from E219 to E258. The Class 4E was amongst the most powerful electric locomotives in the world at that time.
These dual cab locomotives have two large grilles on one side and a passage linking the cabs on the opposite side. When observing the locomotive from the side with the grilles, the number 1 end would be on the right. Like the Classes 1E, 2E and 3E, the Class 4E has bogie mounted draft gear and an articulated inter-bogie linkage, therefore no train forces are transmitted to the locomotive body.
The Class 4E has a 1Co+Co1 wheel arrangement, with an additional bissel truck (pony truck) at the outer end of each of the two three-axle powered bogies. While the Classes 32-000 and 32-200 diesel-electric locomotive types also used this wheel arrangement, it made the Class 4E unique amongst South African electric locomotives.
The Class 4E was specifically built for use on the mainline from Cape Town across the Hex River rail pass to Touws River, from where Class 25 and Class 25NC steam locomotives took over across the stretch of unelectrified mainline to De Aar and from there to either Kimberley or Bloemfontein.
The first locomotives to be delivered were placed in service on the Natal mainline while electrification from Worcester to Touws River was being completed, but they eventually had to be withdrawn from Natal because the severe curvature of the Natal mainline caused their frames to crack.
Number E219 was the first Class 4E locomotive to be relocated to Cape Town, where it initially ran on the 1.5 kV DC power that was at that stage still being used for the Cape Town suburban trains, until the upgrading of the lines to 3 kV DC was completed in November 1954. This restricted its load capacity and mobility.
One Class 4E locomotive even briefly served on the Western Transvaal system while being relocated from Natal to the Cape in 1957, when that system was granted permission to use number E247 for between four and six weeks before the locomotive was forwarded on to Cape Town.
Hex River tunnel scheme
The Class 4E purchase was part of a scheme to eliminate the 1 in 40 (2½%) gradients and severe curves of the Hex River rail pass, that entailed the construction of a series of four tunnels through the Hex River Mountains. The tunnel system would have enabled a single Class 4E locomotive to haul 1,000 ton trains up the resulting 1 in 66 (1½%) gradients.
The Hex River Tunnels scheme (Hexton) was initially started in 1945, but was deferred indefinitely in 1950 as a result of financial constraints. The tunnel scheme was briefly resuscitated in 1965 but was deferred once again in 1966. Work was eventually resumed in 1974 and included the remodelling of the lower section of the deviation between De Doorns and Osplaas stations as well as the construction of the short twin tunnels. This was completed in 1976, at which point financial constraints resulted in yet another postponement. Authority to proceed was only given once again in late 1979.
When the project was resumed, the eastern portal of the longest tunnel was relocated a short distance to the southeast of the original site, while the location of the western portal remained as originally planned during the first attempt. The tunnel system was opened on 27 November 1989, by which time the Class 4Es were already retired after having spent their entire careers double heading trains up the Hex River rail pass.
The Class 4E was delivered in a bottle green livery all over with red buffers. The colour and the almost 22 metres (72 feet) length of the Class 4E quickly earned it the nickname Groen Mamba (Green Mamba). This changed to Groot Mamba (Large Mamba) when the much shorter Class 5E was introduced in 1955 and nicknamed Klein Mamba (Little Mamba).
Soon after they entered service, however, Hex River Valley farmers complained that the bottle green all over colour scheme made the locomotives difficult to see when they were approaching through the vineyards. Yellow lines were then added all around the locomotive to improve its visibility, with various line patterns being used before eventually settling on the V shaped whiskers on the ends that extended onto the sides, and multiple lines around the number plates on the sides. The attractive whiskers livery was eventually adopted for all the electric locomotives of the SAR.
Beginning in 1960, a Gulf Red and yellow whiskers livery gradually replaced the green and yellow.
The NBL works numbers of the Class 4E are shown in the table.
The main picture shows number E238 at rest at the Salt River Depot in Cape Town on 7 January 1966 while the following pictures serve to illustrate some of the liveries used on the Class 4E during its service lifetime.
- Electric locomotive numbering and classification
- Hex River Tunnels
- List of South African locomotive classes
- North British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser
- 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
- Locomotives of the South African Railways (Leith Paxton & David Bourne, 1985), pp126-127, ISBN 0-86977-211-2
- South African Railways & Harbours Photo Journal, Vol. 6, p15, by Les Pivnic
- South African Railways & Harbours Photo Journal, Vol. 19, p9, by Les Pivnic
- Hex River Tunnels
- South African Construction World, July 1990, pp. 60-61
- Railways of Southern Africa Locomotive Guide, 2002 Edition, (Compiled by John N. Middleton), 4E photograph, as amended by Combined Amendment List 4, January 2009
- South African Railways & Harbours Photo Journal, Vol. 7, pp16-17, by Les Pivnic