NEW ZEALAND RAILWAY STEAM 6




New Zealand Railways employed about eleven hundred steam locomotives in all. Early ones were from British builders followed by an early mid period of American suppliers, mainly Baldwin, then a mixture of home and North British building. Haulage requirements were growing so fast that successive new acquisitions rapidly became inadequate in power and numbers. Growth of the railway system was sustained by the relatively under developed main trunk roads of the times that were unsuited to heavy motor truck traffic. The main trunk Auckland-Wellington railway was single line that started to become clogged with the growing frequency of relatively lightly loaded trains, thus it was thought that if the power of each engine was doubled, train weights could be doubled and traffic density halved accordingly. So with that thinking, the highly successful South African Garratts were examined and it was seen that without increasing the driving axle loadings all of the above could be achieved. South African traditions were not followed and a home spun design and order for three vaguely similar locomotives was placed with Beyer-Peacock and delivered in 1928. Three years later I viewed one of these machines abandoned in rotten row at Taumarunui locomotive depot. It had handsome lines but all that glitters is not gold.

In my time at Taihape I was to meet drivers who had driven and fired these locomotives on their stamping ground between there and Taumarunui. From the information gleaned the boilers were really good steamers as long as the mechanical stokers kept going. The coal feed worm frequently failed through the presence of stones and steel scraps in the coal causing drive breakages. The engines could travel quite fast providing the Gresley linked middle cylinder valve did not over-run and throw the engine into violent wheel-spin. The water tankage was insufficient and on 1/40 grades the water flowed from the higher to the lower tank. Time was consumed with frequent stops to refill. In their brief existence two firemen were often carried to take over from the sure to fail mechanical stokers. But that was not all, the crossing loops of the time were too short to accommodate the trains that could be hauled and the draw-gear of most of the existing wagons was too light to withstand the newly imposed forces.

These locomotives were of 4-6-2+2-6-4 wheel arrangement. The driving wheels were 57” diameter and the 6 cylinders (three to each power unit) were 16.5” bore x 24” stroke. The boiler pressure was 200 PSI, the fire grate area 58 square feet. The tractive effort was 51580 pounds and the engine weight was 146.8 tons. In the wake of this failed experiment there has been and still is ongoing speculation as to what if they had met expectations! The system might not have seen the “K” series of locomotives. Perhaps if the Garratt concept had made use of the chassis and running gear of the time tested “Ab” and “Wab” locomotives carrying a slightly smaller boiler with a 48 square feet grate aimed at a more conservative tractive effort of say 42000 pounds they may have become the dominant class.

In 1940 the so called civilized world went mad when the most technically advanced nations entered hate relationships and commenced hurling tons of iron and explosives at each-other and smashing up national infrastructures. This turn of events took me into a three year spell working steam and diesel locomotives on the military railway in the North African desert.