New Zealand Kb Class – Out Now

2023 celebrates 100 years since the opening of New Zealand’s Alpine Railway, The Midland Line or ‘Kb Country’ as it was, and sometimes still is, affectionately known as – and what better way to celebrate than with the mighty Kb class itself for Train Simulator Classic! Available now on the Steam Store.

From the day the Otira Tunnel opened in 1923, traffic on the Midland Line was heavy and constant, causing traffic and scheduling issues from day one. In the early years, the line was almost exclusively worked by ‘Ab’ class 4-6-2 Pacifics, but the loadings were so great that many trains required more than one engine, necessitating duplicate crewing, extra maintenance and additional fuel usage. Delays were common, with trains arriving at either end of the trip in excess of an hour late.

Heavier locomotives, however, weren’t possible until the many viaducts and bridges of the Midland Line were upgraded to support them, an expensive exercise that was put off for a number of years. In the meantime, more powerful ‘G’ class Pacifics, built from cut-down 4-6-2+2-6-4 Garratt Locomotives made their way to the Midland Line, but by the mid 1930’s trains were again being double-headed to keep up with the tonnage.

Meanwhile, from 1932, the New Zealand Government Railways’ own workshops at Hutt in Wellington had begun turning out 4-8-4 ‘K’ class locomotives, a triumph of local loco engineering. The K’s were being put to use throughout the North Island and proving their worth, built to the absolute limits of New Zealand’s small loading gauge, the K’s made an imposing sight as they tackled the grades of the North Island Main Trunk.

As the Depression of the 1930s ended, traffic across the network increased and the New Zealand Railways elected to construct a further two batches of locomotives, 10 for the North Island and 6 for the South Islands Midland Line – these six would differ from their North Island counterparts by being fitted with a ‘Booster Engine’ – which drove the rear axle of the trailing bogie under the cab, giving the locomotives up to another 6000 lb of tractive effort for starting heavy trains or slogging them up hills and the fitting of ‘Thermic Syphons’ to draw cold water from lower in the boiler across the top of the fire. And so, in June of 1939 the first of the ‘Kb’ class 4-8-4’s for the Midland Line rolled out of Dunedin’s Hillside workshops to begin service.

The small fleet of Kb’s were fast into service, from the first, Kb 965, entering in June of 1939 the last, Kb 970, entering traffic that December. Originally fitted with ACFI feedwater heaters and a large metal casing to shroud it, and to add some art-deco styling, the Kb made an impressive sight compared to the smaller Pacifics which it was to replace. The impact of the Kb was as big as the engine itself, with trains immediately running ahead of time, by up to half an hour, instead of consistently late.

Over the years the outward appearance of the Kb was to change considerably with the fitting of Exhaust Steam Injectors and the removal of the ACFI feedwater equipment and shrouding – transforming them from a giant, rolling square to the more traditional of locomotive shapes. The Booster Engines proved continuously problematic, largely due to their hard-to-access nature for maintenance – requiring the entire bogie be removed from the locomotive. However, they remained fitted to the fleet, sometimes in various states of operation, right up until the final years of steam on the Midland Line where they began to be removed as they ceased operating.

In June of 1968, with the arrival of the DJ class of Diesel Electrics and the Midland Line becoming officially dieselised, the Kb’s departed their old home of Springfield and found themselves running goods trains on the Main South Line – though occasionally a Kb would still find its way back to their home of almost 30 years, to tackle the mountain grades once more. But the time of steam was over and over the next year or so the Kb’s met the gas axe, with Kb 968 remaining as the sole survivor of this small, unique class of locomotives.

In Train Simulator Classic, experience the Kb Class in their waning years before the advent of dieselisation, brave the elements and conquer the Midland Line in this imposing and powerful steam mountain workhorse. Pick up the route and the new loco on the Steam Store.