South African Class 6E1, Series 11

Manufacturer

The 3 kV DC Class 6E1, Series 11 electric locomotive was designed and built for the South African Railways (SAR) by Union Carriage and Wagon (UCW) in Nigel, Transvaal, with the electrical equipment supplied by the General Electric Company (GEC).

Forty-five locomotives were delivered in 1984 and 1985, numbered in the range from E2141 to E2185. These were the last Class 6E1 locomotives to be built. 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.

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 and a large hatch door on the roof access ladder side, and only one small panel and a large hatch door on the opposite side.

Series identifying features

The Class 6E1 was produced in eleven series over a period of nearly sixteen years. While some of the 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 locomotives had their sandboxes mounted along the bottom edge of the locomotive body, with the sandbox lids fitting into recesses in the body.

Series 8 and later locomotives could be distinguished from all older models by the large hatch door on each side, below the second small window to the right of the side door on the roof access ladder side, and below the first window immediately to the right of the door on the other side.

The Series 9 to Series 11 locomotives were visually indistinguishable from each other, but could be distinguished from all earlier models by the rainwater drainage holes on their lower sides. These holes were usually covered by so-called buckets, but the covers were absent on a few locomotives. Another distinction was the end doors, which were recessed into the doorframes on Series 9 to Series 11 locomotives, compared to earlier models, which had their end doors flush with the doorframes. In addition, on Series 9 and later models, the split side window on the driver's assistant side was replaced by a single rectangular side window with rounded corners. Finally, unlike all earlier models, all four doors on Series 9 to Series 11 locomotives had rounded corners.

Crew access

The Class 5E, 5E1, 6E and earlier 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.

Side doors with two interconnected latch handles on the outside, such as those which were introduced on the Class 7E1, with one outside handle mounted near floor level and the other at mid-door level, were also introduced on Class 6E1 locomotives, beginning with Series 9.

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.

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.

While the earlier Class 6E1, Series 2 to 7 locomotives had been built with a brake system consisting of various valves, connected to each other with pipes, commonly referred to as a "bicycle frame" brake system, the Class 6E1, Series 8 to 11 locomotives were built with an air equipment frame brake system, commonly referred to as a brake rack. Since the design of the rebuilt Class 18E locomotives included the same brake rack, the rebuilding project was begun with the newer series 8 to 11 locomotives, to reduce the overall cost of rebuilding.

The Class 6E1, Series 11 locomotives which were used in this project, were all rebuilt to Class 18E, Series 1 locomotives. All forty-five Series 11 locomotives were rebuilt by April 2005.