Beyond these bulkheads was the ‘free’ end of the engine. The radiators were positioned on either side, with part bulkheads to provide extra stiffness in the body, and similar, part bulkheads were provided at the other end of the engine room, separating the control equipment from the engine and generator. Immediately behind the cab was a full width 3ins thick bulkhead, heavily insulated, and the door into the engine room was double glazed, to provide protection for the crew from excess noise and heat.
In March 1964, Nigeria placed an order for 29 of the same ‘Zambesi’ design, again using the same Sulzer 6LDA power unit, which was the heart of the NT Class design ordered from Sulzer in the same year. The order for three locomotives was placed in 1964, and many aspects of the design, including the power unit were based on an design that Sulzer-AEI had already supplied to Africa for the Nyasaland and Trans-Zambesia Railway in 1962/3. Compared with the ‘Zambesi’ design delivered around the same time, the NT Class was some 12tons lighter. The effect of the weight of the locomotive and train speeds demanded particular consideration with the bogie design to minimise rail stress, and the effect of bogie movement and axle loads. On top of this they needed to run on lightweight track – 60lbs/yard – with demanding curves in places. The locos needed to operate in a harsh environment, with a hot dry climate and temperatures that exceeded 100 deg F for days on end, and frequent sand and dust storms. The basic design of these locomotives was a joint effort between Sulzer in the UK and SLM in Switzerland, with the overall operational needs laid down by Australia’s Commonwealth Railways to run on the 3ft 6ins gauge line from Port Augusta to Alice Springs.
The power units were supplied from Barrow-in-Furness, on the south-western extremity of the English Lake District, from Vickers Armstrong’s engineering works, and electrical equipment from AEI in the midlands, with the whole package put together by Tulloch in Australia. In this example, which is one of international co-operation, no less than three separate companies were involved in the design and construction of 13 diesel locomotives for freight and mixed traffic duties. But, as I’m sure many of us will remember from school geography, the continent of Australia is very dry, and posed many problems for steam train operations – especially on this route – so it was something of a blessing when diesel traction arrived. The story of the line from South to North in Australia is fascinating one, and the line where ‘The Ghan’ operated – and indeed operates to this day as a private company is even more interesting. In fact, even before the full route had been opened, the Central had been taken over as a section of the Commonwealth Railways, which was already operating the standard gauge route from Port Augusta to Kalgoorlie.