South African Class 17E

The South African Class 17E of 1993 is a South African electric locomotive from the Spoornet era.

During 1993 and 1994 Spoornet modified several Class 6E1, Series 7, 8 and 9 locomotives to improve their braking and traction reliability for service on the Natal mainline. These modified locomotives were reclassified to Class 17E.^[2]

Manufacturer

The 3 kV DC Class 6E1 electric locomotive was built for the South African Railways (SAR) by Union Carriage & Wagon (UCW) in Nigel, Transvaal, with the electrical equipment supplied by the General Electric Company (GEC). UCW did not allocate works numbers to the locomotives that it built for the SAR, but used the SAR unit numbers for their record keeping.^[3]

Class 6E1 characteristics

To ensure the maximum transfer of power to the rails without causing wheelslip, the Class 6E1 was built with sophisticated traction links between the bogies and the frames and equipped with electronic wheelslip detection. These traction struts and linkages were to become a distinguishing feature of most subsequent South African electric locomotive models.^[4]

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 number 2 end. A passage 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.^[1]

Operation

The locomotive is controlled via resistors over which the voltage is dropped in a configuration of series and parallel electrical circuits. The circuit breakers that switch these circuits work under very high power and voltage and are all pneumatically operated for insulation purposes. Compressed air is required to open or close the switch actions and air is also used for the weak field cam switch that also switches under very high currents.^[5]

Upon starting off and in the low notches the major part of the voltage is dropped over the banks of resistors and all four traction motors are in series. As the driver notches up, some of the resistor banks are cut out via the pneumatically operated switches and the voltage increases across the traction motors. The more resistors that are cut out as the driver notches higher, the more power is developed by the traction motors. At around 22 to 28 kilometres per hour (14 to 17 miles per hour) the locomotive switches to a parallel combination, where the two traction motors per bogie are in a series electrical circuit while the two bogies are in parallel electrical circuit. Eventually, when all resistors are cut out, the locomotive is operating in full-field.^[5]

Series identifying features

Series 6 and Series 7 locomotives are visually indistinguishable from each other, but can be distinguished from the older series models by the rain water beading above the small grilles on the sides just to the right of the side doors. Series 8 locomotives can be distinguished from 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.^[1]

The Series 9 locomotives 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, although the covers were absent on several locomotives. Further distinctions were the end doors that were recessed into the doorframes on Series 9 locomotives, compared to earlier models that had the end doors flush with the doorframes. In addition, unlike all earlier models, all four doors on Series 9 locomotives had rounded corners.^[6]

Modification to Class 17E

Class 17E locomotives were modified and reclassified from Class 6E1, Series 7, 8 or 9 locomotives during 1993 and 1994. Key modifications included improved regenerative braking and wheelslip control to improve their reliability on the steep grades and curves of the KwaZulu-Natal mainline.^[2]

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.^[7]

Unlike the Class 16E locomotives, which were renumbered and reclassified but otherwise unmodified semi-permanently coupled pairs of Class 6E1, Series 3 to Series 9 locomotives that merely had their number 1 end cabs abandoned in terms of maintenance, the Class 17Es retained their original unit numbers after reclassification, but with a "17E" marking applied below the locomotive’s unit number behind the driver’s side window.^[2]

Apart from the "17E" markings, they are visually indistinguishable from unmodified Class 6E1s. Those in SAR Gulf Red and yellow whiskers livery that still carried number plates even still showed "6E1" on the plates. Altogether one hundred and thirty-nine Class 6E1 locomotives were modified to Class 17E, of which fourteen were Series 7, fifty-five Series 8 and seventy Series 9.^[2]

Rebuilding to Class 18E

Cab 1 of Class 18E no. 18-328, ex Class 17E no. E2071, Sentrarand, 22 September 2009

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 number 1 end was stripped of all controls and the driver's front and side windows were blanked off in order to have a toilet installed, thereby forfeiting the locomotive's bi-directional ability.^[2][8]

Brake rack in Class 18E no. 18-089

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.^[8]

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 in order to reduce the overall cost of rebuilding. ^[8]

Between 2002 and 2007 all but three of the Class 17Es were rebuilt to Class 18E, Series 1. The exceptions are numbers E1778, E1803 and E2035 which are presumed to have been scrapped. The table shows their Class 6E1 series and numbers, Class 18E numbers and year of rebuilding.

Markings illustrated

The main picture shows Class 17E number E1826, ex Class 6E1, Series 7, at Capital Park in Pretoria on 28 September 2006. The "17E" markings below the locomotive numbers on this and the following picture were the only means to visually distinguish Class 17E locomotives from unmodified Class 6E1 locomotives.

• 

  Class 17E no. E1913, ex Class 6E1, Series 8, at Capital Park, Pretoria, 28 September 2006

See also

• Electric locomotive numbering and classification
• List of South African locomotive classes
• South African Class 6E1, Series 7
• South African Class 6E1, Series 8
• South African Class 6E1, Series 9
• South African Class 16E
• South African Class 18E, Series 1
• South African locomotive history

References

Wikimedia Commons has media related to: South African Class 17E or Class 18E rebuilt from Class 17E

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