South African Class ES1
|South African Class ES1|
|Class ES1 shunting locomotive, circa 1930|
|AAR wheel arr.||B|
|Gauge||3 ft 6 in (1,067 mm) Cape gauge|
|Wheel diameter||38 in (965 mm)|
|Wheelbase||10 ft 5 in (3.175 m)|
|Length||22 ft (6.706 m) over headstocks
24 ft 5 in (7.442 m) over couplers
|Height||10 ft (3.048 m)|
|Axle load||12 long tons (12.3 t) 3⁄20|
|Locomotive weight||24 long tons (24.6 t) 5⁄20|
|Electric system(s)||208 cell battery|
|Transmission||5.4:1 Gear ratio|
|Power output||50 hp (37 kW)|
|Tractive effort||8,500 lbf (38 kN) 1 hour|
|Career||South African Railways
|Power class||235V, 196A|
|Number in class||1|
|Number||E123, renumbered E502|
In 1924 the South African Railways placed a single Class ES1 battery-powered shunting locomotive in service at the construction site of the Colenso power station. In 1927 the power station and the locomotive was sold to the Electricity Supply Commission (ESKOM), and in 1937 the locomotive was purchased back from ESKOM for use at the Danskraal locomotive depot.
During the electrification of the Glencoe to Pietermaritzburg section of the Natal mainline, a mountainous single track line that carried heavy mineral traffic towards the port of Durban on an alignment with severe gradients and tight curves, the Colenso power station was built by the South African Railways (SAR) to supply the power for this line. A single battery-powered electric shunting locomotive, the only battery-powered locomotive to ever see service on the SAR, was purchased from English Electric in 1924 for use at the power station construction site.
The centre-cab locomotive had a Bo wheel arrangement, with the two axles being driven by two 37 kilowatts (50 horsepower) traction motors, operating at 235 volts and powered by a 208 cell nickel-iron alkali type battery with a 435 amp-hour capacity.
The locomotive remained in service at the Colenso power station after 1927, when the power station and all its equipment, including the battery locomotive, was sold to the Electricity Supply Commission (ESKOM), the state-owned South African national power corporation.
In 1937 the locomotive was purchased back from ESKOM by the SAR, designated Class ES1 with running number E123, and stationed at the Danskraal locomotive depot at Ladysmith where it was used as a shunter to move unpowered steam locomotives. Nicknamed "Queen Mary", it was later renumbered to E502. It remained in service at Danskraal until it was withdrawn from service in 1978.
- South African Railways Index and Diagrams Electric and Diesel Locomotives, 2’0” & 3’6” Gauge, circa 1940, as amended
- Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. p. 135. ISBN 0869772112.
- "South African Railways Power Plant". Electric Railway Journal 60 (24): 914. 9 December 1922. Retrieved 15 September 2010.