New Zealand Railways class R
Double Fairlies were used on the winding and steep lines in New Zealand as early as 1872. From 1878 Avonside also manufactured Single Fairlies, which were easier to maintain with a single, larger boiler and a single driving bogie. These were the 18 members of class R and the seven members of the heavier class S.
The class R was able to prove that it was technically capable of reaching a speed of 53 mph or 85 km/h. However, due to the laterally movable bogie, the running smoothness was very poor. However, since the speeds were generally significantly lower, the locomotives could be used successfully. They later received larger water tanks and a new boiler with higher pressure.
The retirements of the class R took place between 1919 and 1944. Three machines were handed over by the NZR to the Sanson Tramway. R 28 was used for shunting in the port of Timaru until 1940. Today she is the only surviving R and only Single Fairlie in New Zealand and is located in Reefton. She was actually planned to be made operational again by 2018, but there is currently nothing further to read about the progress.
Technical data
General
| Property | as built | new boiler |
|---|---|---|
| Built | 1878-1879 | |
| Manufacturers | Avonside | |
| Wheel arrangement | 0-6-4T (Single Fairlie) | |
| Gauge | 1,067 mm (Cape gauge) | |
Dimensions and weights
| Property | as built | new boiler |
|---|---|---|
| Wheelbase | 6.66 m | |
| Service mass | 30.5 t | |
| Adhesion mass | 17.3 t | |
| Rigid wheelbase | 2.06 m | |
| Axle load | 5.8 t | |
| Water capacity | 3,255 l | 4,092 l |
Boiler
| Property | as built | new boiler |
|---|---|---|
| Grate area | 1.115 m² | 1.301 m² |
| Evaporative heating surface | 56.485 m² | 68.87 m² |
| Total heating surface | 56.5 m² | 68.9 m² |
Power plant
| Property | as built | new boiler |
|---|---|---|
| Driver diameter | 914 mm | |
| Boiler pressure | 9 bar | 11 bar |
| Expansion type | simple expansion | |
| Cylinders | two, 311 x 406 mm | |
Power
| Property | as built | new boiler |
|---|---|---|
| Power source | steam | |
| Estimated power | 205 kW (279 PS) | 336 kW (457 PS) |
| Top speed | 85 km/h | |
| Starting effort | 32.8 kN | 40.3 kN |
Calculated values
| Property | as built | new boiler |
|---|---|---|
| Factor of adhesion | 1 : 5.17 | 1 : 4.20 |
| Optimal speed | 39 km/h | 51 km/h |
| Power-to-weight ratio | 6.7 kW/t | 11.0 kW/t |
| Adhesive weight/Total | 1 : 1.76 | |
| Tractive force/Heating surface | 1 : 12.12 | 1 : 12.24 |
| Grate area/Heating surface | 1 : 50.66 | 1 : 52.94 |