NZR KB class

The NZR K^B class of 1939 was a class of steam locomotive that operated on New Zealand's railway network with a wheel arrangement of 4-8-4. They were built for service in the South Island after the success of the K class to meet the increasing traffic demands of New Zealand Government Railways, and were almost totally similar to the North Island K^A class locomotives, except for a special two-cylinder auxiliary "booster" in the rear bogie, the associated piping and equipment for the booster, and the addition of 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 certain lines in the South Island. The locomotives were all built in 1939 by NZGR Hillside Workshops in Dunedin, and unlike their K & Ka Class counterparts, were not converted to oil-firing during the 1940s-50's.

The locomotives first appeared with distinctive stream lining, mainly to hide their ACFI feedwater systems. This streamlining was removed by maintenance staff during the late 1940s - 50s.

The class was largely used on the Christchurch - Arthur's Pass section of the Midland Line. This section became known as "K^B country" in New Zealand railway jargon. They did however sometimes venture onto the Main South Line, mainly during the Second World War.

However, with the introduction of diesel locomotives and railcars the class saw declining use in their final years. The end came following the introduction of the DJ class in 1968, the K^B class were all withdrawn.

Preserved locomotive

External links

• New Zealand Steam Locomotives - K^B class