Commonwealth Railways NSU Class - History

History

By the end of World War 2, the Commonwealth Railways, like every other operator, were surviving on a ragged and worn out collection of rollingstock on their Central, North and Trans Australian lines. Some of the narrow gauge locomotives were fifty or more years old, and the rolling stock not much the younger. George McLeay, then Federal Minister for Fuel, Shipping and Transport, made recommendations to Cabinet in 1950, for the approval of some £4.7 million for upgrading the CR's fleet of both narrow and standard gauge locomotives and rollingstock.

The CR called for tenders, to be submitted by 15 November 1950, for the manufacture, delivery and handing over, in running order, of 14 locomotives for the 1067 mm narrow gauge lines.

The specifications called for certain requirements, the main four being;

• Axle load of no greater than 10.5 tonnes (10.3 long tons; 11.6 short tons);
• Electric transmission;
• Tractive effort at least 21,000 pounds-force (93.4 kN);
• Tri-axle bogies.

Other specifications called for a machine that was able to withstand the rigours of the hostile Central Australian environment, including temperatures upwards of 45 °C, not only for one day, but up to nine at a time, cooling systems able to cope with poor quality water and dust-laden air. They were expected to have a range of 850 miles (1,370 km).

Thirteen companies submitted over thirty designs. However, as the specifications were rigid, most did not get past the first stage of the selection procedure.

The CR's Mechanical Branch also seemed to take preference for slower revving engines. The Sulzer plant finally selected ran at 750 rpm at idle, whereas one design submitted by A. E. Goodwin ran at 1500 rpm. Finlay noted the "CR Mechanical Branch appeared not to have been overly excited about high revving engines, as it feared they would lead to high repair bills. 1000 rpm was considered fast enough". Finlay also notes that the seemed preference for slower speed engines, as well as the requirement of an electrical transmission, resulted in the failure of many of the submitted tenders.

It was initially planned to run the new locomotive from Oodnadatta to Alice Springs and back without having to refill, hence the range of 850 miles (1,370 km). This later proved to be impractical and a 20,000-imperial-gallon (91,000 l; 24,000 US gal) fuel tank was installed at Alice Springs.

In 1951, the CR departed from their apparent tradition of using "well proven" designs, and awarded the contract to build the class of locomotives, later to be known as the NSU, to the Birmingham Railway Carriage and Wagon Company Ltd (BRCW). The Sulzer/BRCW design had won over the English Electric Company's (EE) submission. Whilst EE were obviously a better known company (in Australia), having built many other pioneering Diesel Electrics, Sulzer plants had been used widely in the UK (the earliest UK Sulzer diesels were the Armstrong-Withworth "Universal's" of the 1930s,) and Europe and other exported units, and would go on to power some 690 British Railways machines, using both the 6LDA plant, and later and larger in-line and V- units.

The BRCW tendered a design using a Sulzer 6LDA-28 engine (a six cylinder, in-line, pressure charged unit) that had been derated from 1035 hp at 750 rpm to 955 hp at 750 rpm, powering Crompton Parkinson electric engines set in an A1A-A1A pattern. The diesel engines used in the NSU class were amongst the last engines built built by Sulzer at their Winterthur plant, for use outside of Europe. Later engines were (bar a few exceptions) built under contract by Vickers-Armstrongs, Barrow-in-Furness, England.

In addition to the fourteen units for the CR the BRCW also built an eventual total of six identical units for the Sierra Leone Development Co., West Africa. Five were built with the CR units, and an additional unit was commissioned in 1962.

Part of the Contract with BRCW stipulated that, in view of its 42 years of experience in loco design, Sulzer were to accept full responsibility for the design and performance of the completed loco. The CR had knowledge of Sulzer since the appointment of Deane as its Engineer in Chief of Construction of the Trans line. Deane had proposed in the early days of the TAR that dieselisation was the way to go, and had considered early Sulzer designs then. (Some have suggested that the CR worked with the South Australian Railways to trial diesel traction). However, the technology was not developed enough to be reliable. Deane was a generation ahead of his time.

"Modern Technology" abounded in the unit including chrome connecting rods in the engine, the use of the Sulzer Load Regulating system ("which always ensures that the engine operates....under the most favourable conditions" ), Sulzer Anti-slip Brakes, Serck cooling system elements, dust resistant engine room and filtered air fed traction motors as well as the usual safety systems.