Data from "Stephenson - circa 1951", The History of the Steam Locomotives that have Served The Electricity Supply Industry in South Africa, Eskom, pp. 41-43, archived at [], last accessed 23 July 2020, pp. 52-54. Works numbers were 7398, 7677, and 7685.
7677 is the subject of this chapter in ESCOM's history of South Africa's electricity supply industry locomotives. According to the diagram, 7398 served Johannesberg and the Orlando Power Statios, while 7585 went to Swartkops Power Station.
Unfortunately, this stubby, high-boilered switcher did not perform particularly well. The diagram suggests some reasons why. One was the relatively steep incline to the cylinders, which drove on the rear driving axle and turned small drivers. The other is a short wheelbase compared to the boiler and saddle tank's combined height.
EMSCO's history outlined the problems:
"Stephenson has inside steam chests and valve gear making it difficult to work on these parts. She was rather a rough riding engine, she hunted badly, side swinging kicked the track out of line.
'Operating in a yard presented no problems but on a long run she was like a bucking bronco!"
ESCOM's author described Stephenson as "very well-travelled" in a career that eventually led her to Umgeni Steam Railway Museum in Pinetown.
Principal Dimensions by Steve Llanso of Middle Run Media | |
---|---|
Class | Stephenson |
Locobase ID | 20764 |
Railroad | ESKOM |
Country | South Africa |
Whyte | 0-4-0ST |
Number in Class | 1 |
Road Numbers | |
Gauge | Std |
Number Built | 1 |
Builder | Stephenson & Hawthorns |
Year | 1951 |
Valve Gear | Stephenson |
Locomotive Length and Weight | |
Driver Wheelbase (ft / m) | 5.50 / 1.68 |
Engine Wheelbase (ft / m) | 5.50 / 1.68 |
Ratio of driving wheelbase to overall engine wheelbase | 1 |
Overall Wheelbase (engine & tender) (ft / m) | 5.50 / 1.68 |
Axle Loading (Maximum Weight per Axle) (lbs / kg) | 31,360 / 14,225 |
Weight on Drivers (lbs / kg) | 62,692 / 28,437 |
Engine Weight (lbs / kg) | 62,692 / 28,437 |
Tender Loaded Weight (lbs / kg) | |
Total Engine and Tender Weight (lbs / kg) | |
Tender Water Capacity (gals / ML) | 840 / 3.18 |
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 0.95 / 1 |
Minimum weight of rail (calculated) (lb/yd / kg/m) | 52 / 26 |
Geometry Relating to Tractive Effort | |
Driver Diameter (in / mm) | 42 / 1067 |
Boiler Pressure (psi / kPa) | 165 / 1140 |
High Pressure Cylinders (dia x stroke) (in / mm) | 14" x 22" / 356x559 |
Tractive Effort (lbs / kg) | 14,399 / 6531.28 |
Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.35 |
Heating Ability | |
Tubes (number - dia) (in / mm) | 124 - 1.75" / 44 |
Flues (number - dia) (in / mm) | |
Flue/Tube length (ft / m) | 9.85 / 3 |
Firebox Area (sq ft / m2) | 55 / 5.11 |
Grate Area (sq ft / m2) | 8.50 / 0.79 |
Evaporative Heating Surface (sq ft / m2) | 623 / 57.88 |
Superheating Surface (sq ft / m2) | |
Combined Heating Surface (sq ft / m2) | 623 / 57.88 |
Evaporative Heating Surface/Cylinder Volume | 158.94 |
Computations Relating to Power Output (More Information) | |
Robert LeMassena's Power Computation | 1403 |
Same as above plus superheater percentage | 1403 |
Same as above but substitute firebox area for grate area | 9075 |
Power L1 | 2646 |
Power MT | 186.10 |