South African Class 6E1, Series 7

Manufacturer

The 3 kV DC Class 6E1, Series 7 electric locomotive was designed and built for the South African Railways (SAR) by Union Carriage and Wagon (UCW) in Nigel, Transvaal. The electrical equipment was supplied by the General Electric Company (GEC).

The 150 locomotives were delivered between 1977 and 1979, numbered in the range from E1746 to E1895. UCW did not allocate builder’s or works numbers to the locomotives which it built for the SAR and used the SAR unit numbers for their record keeping.

Bogies

The Class 6E1 was built with sophisticated traction linkages on their 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. This feature is controlled by electronic wheel-slip detection devices and an electric weight transfer relay, which reduce the anchor current to the leading bogie by as much as 50A in notches 2 to 16.

Brakes

The locomotive itself used air brakes, but it was equipped to operate trains with air or vacuum brakes. While hauling a vacuum braked train, the locomotive's air brake system would be disabled and the train would be controlled by using the train brakes alone to slow down and stop. While hauling an air braked train, on the other hand, the locomotive brakes would engage along with the train brakes. While working either type of train downgrade, the locomotive's regenerative braking system would also work in conjunction with the train brakes.

When the locomotive was stopped, the air brakes on both bogies were applied together. The handbrake or parking brake, located in Cab no. 2, only operated on the unit's last axle, or no. 7 and 8 wheels.

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 marked as the no. 2 end. A corridor along the centre of the locomotive connects the cabs, which are identical apart from the fact that the handbrake is located in cab 2. A pantograph hook stick is stowed in a tube mounted below the lower edge of the locomotive body on the roof access ladder side. The locomotive has three small panels along the lower half of the body on the roof access ladder side, and only one panel on the opposite side.

Series identifying features

The Class 6E1 was produced in eleven series over a period of nearly sixteen years. While some Class 6E1 series are visually indistinguishable from their predecessors or successors, some externally visible changes did occur over the years. Series 1 locomotives had their sandboxes mounted on the bogies, while Series 2 to 11 had their sandboxes mounted along the bottom edge of the locomotive body, with the sandbox lids fitting into recesses in the body.

The Series 6 and Series 7 locomotives are visually indistinguishable from each other, but can be distinguished from all the older series models by the rainwater beading which was added above the small grilles on the sides just to the right of the side doors. Beginning with Series 8, all subsequent series had a large hatch door on each side to the right of their side doors.

Crew access

The Class 5E, 5E1, 6E and 6E1 locomotives are notoriously difficult to enter from ground level since their lever-style door handles are at waist level when standing inside the locomotive, making it impossible to open the door from outside without first climbing up high enough to reach the door handle while hanging on to the side handrails with one hand only. Crews therefore often chose to leave the doors ajar when parking and exiting the locomotives.

Late model Series 7 locomotives were equipped with side doors on which the outside door latch handle is mounted near floor level, with a simple drawer pull type handle at mid door level. No. E1845 and later locomotives were observed with the lower mounted door handles. No. E1882 is one observed exception, with a high mounted door handle, although this may have been the result of a door replacement.

Service

The Class 6E1 family saw service all over both of the 3 kV DC mainline and branchline networks, the smaller Cape Western network between Cape Town and Beaufort West, and the larger network which covers portions of the Northern Cape, the Free State, Natal, Gauteng, North West Province and Mpumalanga.

Reclassification to Class 16E

During 1990 and 1991, Spoornet semi-permanently coupled several pairs of otherwise largely unmodified Class 6E1 locomotives, reclassified them to Class 16E and allocated a single locomotive number to each pair, with the individual locomotives in the pairs inscribed "A" or "B". The aim was to accomplish savings on cab maintenance by coupling the locomotives at their no. 1 ends, abandoning the no. 1 end cabs in terms of maintenance and using only the no. 2 end cabs. Most pairs were later either disbanded, with the locomotives reverting to Class 6E1 and regaining their original numbers, or rebuilt to Class 18E.

Twelve known Series 7 locomotives were part of such Class 16E pairs.

Modification to Class 17E

Class 17E locomotives were modified and reclassified from Class 6E1, Series 7, 8 and 9 locomotives during 1993 and 1994. Key modifications included improved regenerative braking and wheel-slip control, to improve their reliability on the steep gradients and curves of the Natal mainline. Unlike the unmodified but reclassified Class 16E locomotives, the Class 17Es retained their original unit numbers after reclassification.

A stumbling block was that the regeneration equipment at many of the sub-stations along the route was unreliable, and since there was no guarantee that another train would be in the same section to absorb the regenerated energy, there was always the risk that line voltage could exceed 4.1 kV, which would make either the sub-station or the locomotive trip out. As a result, the subsequent rebuilt Class 18E locomotives were not equipped with regenerative braking.

Fourteen Series 7 locomotives are known to have been modified and reclassified to Class 17E, their numbers being E1749, E1775, E1776, E1777, E1778, E1801, E1803, E1805, E1810, E1822, E1826, E1827, E1832 and E1843.

Rebuilding to Class 18E

In 2000, Spoornet began a project to rebuild Series 2 to 11 Class 6E1 locomotives to Class 18E, Series 1 and Series 2 at the Transnet Rail Engineering (TRE) workshops at Koedoespoort. In the process, the cab at the no. 1 end was stripped of all controls and the driver's front and side windows were blanked off to have a toilet installed, thereby forfeiting the locomotive's bi-directional ability.

Since the driving cab's noise level had to be below 85 decibels, cab 2 was selected as the Class 18E driving cab, primarily based on its lower noise level compared to cab 1, which is closer and more exposed to the compressor's noise and vibration. Another factor was the closer proximity of cab 2 to the low voltage switch panel. The fact that the handbrake was located in cab 2, was not a deciding factor, but was considered an additional benefit.

Most of the Class 6E1, Series 7 locomotives which were used in this project, were rebuilt to Class 18E, Series 1 locomotives. The known numbers and renumbering details are listed in the table.

Illustration

All the Class 6E1, Series 7 locomotives were delivered new in the SAR Gulf Red and yellow whiskers livery. The main picture shows no. E1807 in Spoornet maroon livery, passing through Kaalfontein on 23 September 2009. Illustrated below are some of the other liveries in which Series 7 locomotives served.