NZR Kb class
|
|||||||||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||||||||
| Type and origin | |
|---|---|
| Power type | Steam |
| Builder | NZR Hillside Workshops, Dunedin |
| Build date | 1939 |
| Specifications | |
|---|---|
| Configuration | 4-8-4 |
| Gauge | 3 ft 6 in (1,067 mm) |
| Wheel diameter | 54 in (1.372 m) |
| Wheelbase | 34 ft 10 in (10.62 m) |
| Length | 69 ft 8 in (21.23 m) |
| Width | 8 ft 6 in (2.59 m) |
| Height | 11 ft 6 in (3.51 m) |
| Adhesive weight | 56.0 long tons (56.9 t; 62.7 short tons) |
| Loco weight | 94.8 long tons (96.3 t; 106.2 short tons) |
| Tender weight | 52.9 long tons (53.7 t; 59.2 short tons) |
| Total weight | 147.7 long tons (150.1 t; 165.4 short tons) |
| Fuel type | Coal |
| Fuel capacity | 7.5 long tons (7.6 t; 8.4 short tons) |
| Water cap | 5,000 imp gal (23,000 L; 6,000 US gal) |
| Firebox: • Firegrate area |
47.7 sq ft (4.4 m2) |
| Boiler pressure | 200 psi (1,379 kPa) |
| Feedwater heater | ACFI |
| Heating surface | 1,984 sq ft (184.3 m2) |
| Superheater: |
|
| • Heating area | 485 sq ft (45.1 m2) |
| Cylinders | 2 driving 2 booster |
| Cylinder size | 20 in × 26 in (508 mm × 660 mm) |
| Performance figures | |
|---|---|
| Power output | 1,400 hp (1,000 kW) |
| Tractive effort | 30,815 lbf (137.07 kN) 36,815 lbf (163.76 kN) with booster |
| Career | |
|---|---|
| Number in class | 6 |
| Numbers | 965 - 970 |
| Locale | South Island of New Zealand, mainly the Midland line |
| First run | 1939 - 1940 |
| Last run | December 1968 |
| Retired | 1967 - 1969 |
| Current owner | Mainline Steam |
| Disposition | Withdrawn; 1 preserved |
The NZR KB class of 1939 was a class of mixed traffic steam locomotives that operated on New Zealand's railway network. They were built by the New Zealand Railways Department (NZR) after the success of the K class to meet the increasing traffic demands on the Midland Line in the South Island. The locomotives had a wheel arrangement of 4-8-4 and first appeared with distinctive streamlining, mainly to hide their ACFI feedwater systems.
Following the success of the K class in the North Island, there was a need for similar locomotives to operate the Midland Line, primarily between Springfield and Arthur's Pass. These new locomotives incorporated a number of improvements upon the K class, including a re-designed plate frame to eliminate cracking issues the K class experienced; roller bearings on all wheels; hydrostatic lubrication throughout; and the inclusion of the ACFI feed-water system that had been pioneered on K 919. The ACFI equipment's aesthetic appearance had been criticised, hence the KB and contemporary KA classes were both fitted with shrouding to obscure it.
The KB class were technically very similar to the KA class, but were distinguished by the inclusion of a booster on the rear axle of the trailing bogie and Nicholson thermic syphons in the firebox. The use of the booster, first proposed for the K class in 1932, was mainly due to steeper gradients and heavy freight trains on the Midland Line, especially Cass bank. Additional piping and sanding equipment for the booster gave the KB a slightly different appearance to the KA. The booster was intended solely for use at low speed, and some class members ultimately had the booster removed due to problems such as jamming in gear, reducing the locomotive's top speed.
...
Wikipedia