Data from Holland (Vol II, 1972).
This class was designed by Hazlett M Beatty to cope with 1.25% grades on the Beaufort West-De Aar service in the west. The first two, 903-904 built by Kitson, showed themselves powerful and reliable engines. They were joined a year later by four slightly larger engines -- 905-906 -- delivered by Beyer, Peacock, & Co.
NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | 5A/5B - Karoo |
| Locobase ID | 2920 |
| Railroad | Cape Government |
| Country | South Africa |
| Whyte | 4-6-2 |
| Number in Class | 2 |
| Road Numbers | 903-904 |
| Gauge | 3'6" |
| Number Built | 2 |
| Builder | several |
| Year | 1903 |
| Valve Gear | Stephenson |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 10.83 / 3.30 |
| Engine Wheelbase (ft / m) | 28.20 / 8.60 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.38 |
| Overall Wheelbase (engine & tender) (ft / m) | 49.10 / 14.97 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 28,560 / 12,955 |
| Weight on Drivers (lbs / kg) | 85,568 / 38,813 |
| Engine Weight (lbs / kg) | 134,736 / 61,115 |
| Tender Loaded Weight (lbs / kg) | 71,680 / 32,514 |
| Total Engine and Tender Weight (lbs / kg) | 206,416 / 93,629 |
| Tender Water Capacity (gals / ML) | 3390 / 12.84 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 5.50 / 5 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 48 / 24 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 60 / 1524 |
| Boiler Pressure (psi / kPa) | 180 / 1240 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 18.5" x 26" / 470x660 |
| Tractive Effort (lbs / kg) | 22,691 / 10292.48 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.77 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 154 - 2.25" / 57 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 14.52 / 4.43 |
| Firebox Area (sq ft / m2) | 115 / 10.69 |
| Grate Area (sq ft / m2) | 26 / 2.42 |
| Evaporative Heating Surface (sq ft / m2) | 1427 / 132.62 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 1427 / 132.62 |
| Evaporative Heating Surface/Cylinder Volume | 176.41 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 4680 |
| Same as above plus superheater percentage | 4680 |
| Same as above but substitute firebox area for grate area | 20,700 |
| Power L1 | 4455 |
| Power MT | 344.34 |