South Australian Railways 2-8-4 Locomotives in Australia
Class Details by Steve Llanso of Sweat House Media
Class 720B (Locobase 5688)
Data from Douglas Colquhoun's entries presented in the Australian national railway museum site: [
] (visited 14 October 2003). See also [
], last accessed 8 March 2015.
The only "Berkshires" in Australian service, these were enlargements of the "Mighty 700s". Five were delivered in 1930-1931, Three each in 1938, 1939, 1942, and 1943. Before the class's retirement in 1958-1960, the least-used of the class had accumulated 411,097 miles in service. Of those delivered in the early 1930s, the class leader covered 729,376 miles before its 14 April 1960 withdrawal.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | 720B |
| Locobase ID | 5688 |
| Railroad | South Australian Railways |
| Country | Australia |
| Whyte | 2-8-4 |
| Number in Class | 17 |
| Road Numbers | 720-736 |
| Gauge | 5'3" |
| Number Built | 17 |
| Builder | Islington |
| Year | 1930 |
| Valve Gear | Walschaert |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 15.50 / 4.72 |
| Engine Wheelbase (ft / m) | 37.08 / 11.30 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.42 |
| Overall Wheelbase (engine & tender) (ft / m) | 73.25 / 22.33 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 44,454 / 20,164 |
| Weight on Drivers (lbs / kg) | 172,704 / 78,337 |
| Engine Weight (lbs / kg) | 277,312 / 125,787 |
| Tender Loaded Weight (lbs / kg) | 232,960 / 105,669 |
| Total Engine and Tender Weight (lbs / kg) | 510,272 / 231,456 |
| Tender Water Capacity (gals / ML) | 10,800 / 40.91 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 19 / 17 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 72 / 36 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 57 / 1448 |
| Boiler Pressure (psi / kPa) | 220 / 1520 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 22" x 28" / 559x711 |
| Tractive Effort (lbs / kg) | 44,460 / 20166.74 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.88 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | |
| Firebox Area (sq ft / m2) | 360 / 33.46 |
| Grate Area (sq ft / m2) | 46.80 / 4.35 |
| Evaporative Heating Surface (sq ft / m2) | 2975 / 276.49 |
| Superheating Surface (sq ft / m2) | 751 / 69.80 |
| Combined Heating Surface (sq ft / m2) | 3726 / 346.29 |
| Evaporative Heating Surface/Cylinder Volume | 241.49 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 10,296 |
| Same as above plus superheater percentage | 12,355 |
| Same as above but substitute firebox area for grate area | 95,040 |
| Power L1 | 19,568 |
| Power MT | 999.17 |