South African Railways 2-8-4 Locomotives in South_Africa

Class Details by Steve Llanso of Sweat House Media

Class 24 (Locobase 2923)

Data from South African Rys & Harbours 8 -1941Locomotive Diagrams supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange collection; "South African Class 24 2-8-4" in Wikipedia at [], last accessed on 19 September 2022; and A E Durrant (1972). Works numbers were 23313-24312 in 1949-1950. (3675 was the 2,000th locomotive delivered by NBLC to South African railways, a benchmark celebrated by naming it Bartolomew Dias.)

Designed by Chief Mechanical Engineer (CME) Dr. M M Loubser over a ten-year period, these were only Berkshires on the SAR. Many were concentrated in the SouthWest Africa area. Impressive engines running on 45-lb/yard (22.5 kg/m) rail. (As big as they were Locobases 3839, 3842-3843 (Japan), 4329 (Kenya) trailed tenders, 6480 (Chile), and 3722 (Argentina). In most dimensions, these were half-size versions of the Class 23 Mountains.

Baldwin's General Steel Castings plant in Eddystone, PA supplied the cast-steel main frames with integral cylinders and the six-axle tender's Buckeye bogies. Firebox heating surface included 16 sq ft (1.49 sq m) of arch tubes.

Although the 24s delivered good steam power, dieselization and electrification considerably shortened their likely service lives to an average of 15 years or less. The upside for posterity soon appeared as 23 of the 24s wound up in displays or operational heritage operations in South Africa. In addition, the 3620 traveled across the Pacific to New Zealand's Main Line Steam Trust in 1997.

Four years later, it crossed the Tasman Sea to Cairns, Australia1. Not long after it began service, 3620 was idled for restoration for 13 years. Russell Newman posted the following update on 7 March 2021:

"After 13 years out of action the ex South African Railways Glasgow North British Locomotive Company built Class 24 2-8-4 No. 3620 has successfully completed its test runs at the Bellarine Peninsular Railway in Victoria State. During the locomotive's restoration, several major changes and additions have been made to No. 3620 which is now equipped with air brakes and oil firing, along with a bell, smokebox headlight and front numberplates being fitted at its owner Mr Ian Welch's request."

The engine then re-entered service to pull the six light-blue carriages on the Q Train's "Rail Restaurant".

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID2923
RailroadSouth African Railways (SAR)
CountrySouth Africa
Number in Class100
Road Numbers3601-3700
Number Built100
BuilderNorth British
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)13.48 / 4.11
Engine Wheelbase (ft / m)31 / 9.45
Ratio of driving wheelbase to overall engine wheelbase 0.43
Overall Wheelbase (engine & tender) (ft / m)65.26 / 19.89
Axle Loading (Maximum Weight per Axle) (lbs / kg)25,761 / 11,685
Weight on Drivers (lbs / kg)100,127 / 45,417
Engine Weight (lbs / kg)163,296 / 74,070
Tender Loaded Weight (lbs / kg)126,673 / 57,458
Total Engine and Tender Weight (lbs / kg)289,969 / 131,528
Tender Water Capacity (gals / ML)5399 / 20.45
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 9.90 / 9
Minimum weight of rail (calculated) (lb/yd / kg/m)42 / 21
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)51 / 1295
Boiler Pressure (psi / kPa)200.20 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)19.02" x 25.98" / 483x660
Tractive Effort (lbs / kg)31,360 / 14224.67
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.19
Heating Ability
Tubes (number - dia) (in / mm)76 - 2.52" / 64
Flues (number - dia) (in / mm)24 - 5.512" / 140
Flue/Tube length (ft / m)17.75 / 5.41
Firebox Area (sq ft / m2)138.96 / 12.91
Grate Area (sq ft / m2)35.95 / 3.34
Evaporative Heating Surface (sq ft / m2)1636 / 151.99
Superheating Surface (sq ft / m2)380 / 35.30
Combined Heating Surface (sq ft / m2)2016 / 187.29
Evaporative Heating Surface/Cylinder Volume191.49
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation7197
Same as above plus superheater percentage8565
Same as above but substitute firebox area for grate area33,106
Power L111,454
Power MT1008.79

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