Data from Howell, Comparative Statistics of the Australasian Railways, Journal of the Royal Statistical Society, March 1899, pp. 98-99 and John Garner's [], last accessed 7 September 2008.
These radial tanks were rebuilds of rebuilds. At first, in 1892, the NZGR shops enlarged the F class with larger cylinders and side tanks replacing the saddle tank; these were the Fa. In 1897, the shops produced a new locomotive to a modified design that was further modified with a trailing axle and a piston valve set into the slide-valve chest. In 1902, six more followed from Addington. Thirteen more Fb were created when Fa were modified beginning in 1903, after which all 20 locomotives were designated Fa.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | Fb / Fa |
| Locobase ID | 9571 |
| Railroad | New Zealand Government Railways |
| Country | New Zealand |
| Whyte | 0-6-2T |
| Number in Class | 20 |
| Road Numbers | |
| Gauge | 3'6" |
| Number Built | 7 |
| Builder | NZR shops |
| Year | 1897 |
| Valve Gear | Stephenson |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 10.50 / 3.20 |
| Engine Wheelbase (ft / m) | 16.50 / 5.03 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.64 |
| Overall Wheelbase (engine & tender) (ft / m) | 16.50 / 5.03 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |
| Weight on Drivers (lbs / kg) | 56,448 / 25,604 |
| Engine Weight (lbs / kg) | 65,632 / 29,770 |
| Tender Loaded Weight (lbs / kg) | |
| Total Engine and Tender Weight (lbs / kg) | |
| Tender Water Capacity (gals / ML) | 960 / 3.64 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 1.80 / 2 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 31 / 15.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 36.50 / 927 |
| Boiler Pressure (psi / kPa) | 160 / 1100 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 12" x 18" / 305x457 |
| Tractive Effort (lbs / kg) | 9658 / 4380.80 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 5.84 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | |
| Firebox Area (sq ft / m2) | 50 / 4.65 |
| Grate Area (sq ft / m2) | 10.70 / 0.99 |
| Evaporative Heating Surface (sq ft / m2) | 530 / 49.26 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 530 / 49.26 |
| Evaporative Heating Surface/Cylinder Volume | 224.94 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 1712 |
| Same as above plus superheater percentage | 1712 |
| Same as above but substitute firebox area for grate area | 8000 |
| Power L1 | 3222 |
| Power MT | 377.51 |