There is a famous rail route that runs over 1,800 miles from Adelaide / Port Augusta in South Australia to Darwin in the Northern Territory by way of the equally world-renowned town of Alice Springs. The history of railway development in Australia might be described as a patchwork of different shapes, sizes, lengths and ownership, and this route is also home to the “The Ghan Express”, or more commonly “The Ghan”, which has an equally chequered history.
The line was built in various stages between 1879 and 1929 – by which date it had reached Alice Springs – was opened between Port Augusta and Alice Springs as the Central Australian Railway and built to the narrow gauge of 3ft 6ins – thus adding to the country’s complement of rail gauges. 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.
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. 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.
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. 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.
General Design & Ordering
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 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. On top of this they needed to run on lightweight track – 60lbs/yard – with demanding curves in places.
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. Compared with the ‘Zambesi’ design delivered around the same time, the NT Class was some 12tons lighter.
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. 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 bodies of these locomotives had a very different design and construction than many of the more conventional designs of the day – as a rectangular full width box, the bodysides were created as stressed skin forms, or semi-monocoque. Fabrication of the assembly used rolled steel sections, covered with sheet steel panels, and to provide the rigidity against deformation, a series of closely spaced vertical pillars and horizontal rails was used.
This provided a fully integral structure, with the bodysides connected by headstocks, bolsters, crossbars, deck plates, and bulkheads separating the cab at one end from the radiator compartment and engine room. The coupler height was a particular issue with the NT Class and to handle buffing loads of up to 150 tons, a triangular fabrication was installed at each end behind the drawgear.
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. 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. Beyond these bulkheads was the ‘free’ end of the engine.
In its final form, the cab was placed at the No.2 end of the loco, although there had been some consideration of the design having a cab at each end. The reason given for the cab at the No.2 end was again to do with the nature of the track it would run on, and having the cab at the No.2 end would make for better weight distribution. Another interesting departure from the original design in the NT class was that after the first order was delivered, the following two orders and 10 locomotives were built with a body some nine inches wider.
The engine, an uprated version of the 960hp 6LDA28 series fitted into Class NSU locos, was exhaust pressure charged and intercooled, delivering 1,400hp, and running at 800 rpm. At the time of their construction 4-stroke medium speed engines were commonly used in the UK and many countries, and the Sulzer engines were all built in the Engineering Works of Vickers-Armstrongs in Barrow-in-Furness. By the time these engines were built in Barrow, the works had already constructed around 1,000 of 6, 8 and 12 cylinder types for British Railways, and of course many for other countries, including the ‘Zambesi’ design for Africa.
For the NT Class though, fitting the engine and generator assembly in the body of the loco really drove the design, since to meet the height requirement specified by the design it was necessary to mount the engine below the deck plating. This meant that a conventional underframe could not be used, and the loco’s bodysides would be the main load bearing elements, taking both traction forces and equipment loading through cross stretchers. Hence the stressed skin technique.
The engine itself required major changes to the workplace at the Vickers site in Barrow, and a large proportion of the engineering output there was focussed on building diesel engines, including marine types, along with cement plant, boilers, armaments and equipment for nuclear submarines. In fact Vickers, Barrow first Sulzer engine order was received in 1947, but in 1955 orders began to be received in large numbers from British Railways, which led to the company creating a separate Traction Division to manage the design, build, testing and inspection of the Sulzer engines. According to a commemorative brochure to mark the 1,000th engine:
“The manufacture of Sulzer engines can generally be undertaken on general purpose machine tools but specialised techniques have been developed to assist the large scale productions and inspection of these engines. Extensive use is made of jigs and tools to ensure the interchangeability of all finished parts.”
In the 1960s, Vickers, Barrow was a very busy works, and by the time the Australian order for 6LDA Sulzer diesels arrived, they had already built 1,000 of the Sulzer LDA design. The power unit was used in the earlier A1A-A1A locos built for Commonwealth Railways over a decade earlier.
As a 4-stroke design, Sulzer engines were already easy on fuel, but for the Australian order, the ‘Zambesi’ variant provided lower fuel consumption, and showed good consumption over the full working range. The cylinder block was described as being “… of the wet liner type …” with a single camshaft on the outside operating the valve gear and fuel injection pumps. Fibre glass inspection panels and a full length steel cover on each side of the engine provided access to fuel pumps and crankcase. The latter was built from a number of transverse cast steel members welded to mild steel fabricated longitudinal elements.
The engine was completed by being mounted on side girders, fabricated in a box section, and extended at one end to provide a mounting for the generator. The design and manufacture of the engine provided a significant contribution to reducing the overall weight, and the subsequent impact loading on the lightweight rail used on the narrow gauge networks. In addition, by comparison with the NSU Class, the new locomotive’s power unit provided some 50% more power, and had been tested to achieve a 1,540hp over 1 hour on test at the Test House in Barrow.
The electrical equipment – generator and 6 traction motors were supplied by AEI. The generator, an AEI TG 5302W was mounted at the far end of the loco from the cab and connected to the engine with a solid coupling. The generator armature shaft connected to an auxiliary drive gearbox mounted on the main generator’s end frame of the main generator in a clover leaf format and provided three separate auxiliary drives. One of these was located vertically above the main generator shaft, the other two below to the left and right respectively. The auxiliary generator provided power for lighting, control systems and battery charging.
Immediately behind the cab/engine room bulkhead the cooling radiators were sited on either side of the loco, together with the combined fuel, lubricating oil and water pump set. For cooling the engine only one circuit was used for cooling the engine, lubricating oil and charging air. The advantage claimed by the builders for this simple system was that under all conditions of load the temperature of the engine water, lubricating oil and charging air would be kept at the correct value. This equipment was supplied by Serck and claimed to provide ample margin for operation under the extreme climate conditions of the line.
With so few partitions and bulkheads, ventilation of the engine room was an important aspect of keeping operating and maintenance costs low, as well as combating the harsh environment. The outside air was drawn from the top of the roof at the rear end of the locomotive through an axial flow fan and passed through filters into the engine compartment, effectively providing a positive pressure environment, to exclude fine dust and sand. Additional air flow was provided via the traction motor blowers.
Running Gear and Transmission
Below decks so to speak, the locomotive body and power unit was carried on a pair of 3 axle bogies. The bogie proper was a mixture of cast and fabricated components in a design intended to provide a good ride quality, with the metal-to-metal contact elements replaced by in rubber, and other non-metallic materials. The basic assembly followed the same pattern as the ‘Zambesi’ class for Africa, where rolled mild steel sections and plates were welded into sub-assemblies to form a box-section frame.
Primary springing used helical coil springs between the equalising beams and the bogie frame, with four sandwich rubber units widely spaced providing secondary springing, and hydraulic dampers fitted at each primary spring location. The secondary springing also reduced the weight transfer during periods when the loco was working hard or exerting higher tractive effort.
The bogies of course carried the clasp type brake gear, and this was operated by Australian Westinghouse air-brake system, and followed standard Commonwealth Railways practices. Another weight saving aspect of the design was the aluminium fuel tank, which was “U” shaped in order to allow space to fit the inter-bogie control mechanism. This latter’s purpose was designed to reduce the wear on tyre flanges when running through tight curves, by ensuring the wheels were at the best angle to the rail. This assembly consisted of a pair of yoke arms, running on rollers supported by a body mounted bracket, with the yoke arms on each bogie were connected by a coupling. The braking system on the new NT Class was pretty standard for the 1960s, with clasp type tread brakes and rigging, operated by Australian Westinghouse supplied air-brakes.
Each bogie carried three AEI Type 253AZ 149hp traction motors driving each axle, in the conventional nose suspended, axle hung arrangement. Again, these were the same as fitted to the ‘Zambesi’ design – 4-pole, series wound, and with 3 pairs permanent connected in series, with three stages of field weakening. The final drive to the wheels was achieved using a pinion on the motor shaft driving the axle mounted solid spur gear wheel with a ratio of 92/19, and the whole assembly was enclosed in a sheet steel casing.
Overall control is electro-pneumatic, with the relays/switches located in the control cubicle at the ‘B’ end of the locomotive providing the operation of the different stages of traction motor field weakening. The cubicle was effectively sealed from the rest of the engine/generator compartment and supplied with air taken from the traction motor blowers, at a slightly higher pressure.
The output from the engine to the main generator used a hydraulic load regulator, linked to the engine governor, and an 18 notch master controller, mounted in a pedestal style in the cab regulated the engine speed and power. The train crew were provided with a range of visual and audible alarms for earth faults, wheel slip, high water temperature and low oil pressures, amongst other alarms.
The NT Class were equipped to operate in multiple, and up to three locos could be coupled together and driven from one cab, whilst it was also possible to operate in multiple with the earlier NSU Class A1A-A1A design. It was claimed at the time of their introduction that, at 1400hp, they were the most powerful diesel locos for their weight anywhere in the world.
Numbering & Operations
The first order for the three new NT Class locos was driven by increased passenger and freight traffic, and as a result Commonwealth Railways placed its order for a locomotive type with Tullocch Ltd of Rhodes, Sydney. The design needed to be innovative because of the quite badly laid 3ft 6ins gauge tracks of the Central Australia Railway. The first three were set to work on the section of line between Maree and Alice Springs.
Overall, at first glance, the orders for the NT Class appear quite haphazard – the first 3 in 1964, then an order for 3 more in 1966, and a final order for 7 in 1968, bringing the total to 13. The second order was placed to meet an expected increase in iron ore traffic from the Frances Creek mine on the Northern Australia Railway, and as the tonnage taken out of the Frances Creek mine continued to increase the third order was placed.
The first of the new 1400hp diesels was delivered to the Central Railway for service on the demanding route through the Flinders Range mountains between Port Augusta, Maree, Oodnadatta and Alice Springs. When NT65 was delivered in April 1965, it was decided to name the first of the class after the then Transport Minister- Gordon Freeth – and it remained the only named example of diesels on this route.
NT65 to NT67 were delivered from the Tulloch Works on standard gauge transfer bogies to Broken Hill, where the 3ft 6ins gauge bogies were fitted, and working initially from Quorn, through the Pichi Richie Pass to Port Augusta. In addition to passenger traffic, the coalfields to the northwest of the Flinders Range provide significant freight traffic, and where before a pair of the older NSU diesels would be used, the same working would need only a single NT.
The same process was followed for delivery of the remaining locomotives between 1966 and 1968, and, given that the standard gauge route to Alice Springs was by then in operation, the NTs destined for the Northern Railway were shipped overland from Alice. This involved removing the NTs bogies, and carrying the three new locos on low loaders across country along the Stuart Highway.
The second order for three more NT class locos were sent to the Northern Railway, which were joined by another five from the third order. The remaining two NTs were retained for duties on the Central Railway. The final seven were all intended for the Northern, as the output of iron ore continued to grow rapidly, and which led to the transfer of one of the class on the Central – NT67 – as a temporary measure.
In 1971 the Central was again seeing some new motive power – the Clyde built NJ Class locos, which allowed for the remaining NTs to be sent to the Northern, where they saw out their final years.
The Northern Railway was just over 300 miles long from Darwin to Birdum, but no connection to Alice Springs. In the south, services operated over the Central Railway consisted of passenger and freight, running from Port Augusta to Maree, on to Oodnadaata and finally Alice Springs, a distance of over 770 miles.
Iron ore from the Frances Creek was at the heart of a very serious accident, with no fewer than four NT Class engines involved on 4th November 1972, and which led to the loss of three complete locomotives, and damage to the fourth.
The Darwin Accident
This was the Northern Territory’s worst rail accident and involved four NT Class locos, and this recorded quote provides an interesting description:
“Just after 5am on a November morning in 1972, a train fully loaded with iron ore crashed into a stationary train at Darwin’s Frances Bay rail yards. One railway official said, “I never saw anything like it. I ran down there expecting to be pulling bodies out of the wreckage.” But incredibly, there were no casualties, even among the crew of the runaway train, who had realised it was out of control and jumped out in time. However the accident destroyed over $1 million worth track and rolling stock.”
The locos involved were NT68, 70, 71 and 75. NT70, 71 and 75 were written off after the accident, and although NT68 survived, it survived only another 6 years in service, and was scrapped in 1978.
By the 1970s the Northern and Central Railways had been vested in the Commonwealth Railways, and a decade after NT65’s arrival, four were operating on the Central and the remaining nine on the Northern, all became assets of Australian National.
For the NT Class locos it could be argued, their time was almost up before they were put to work, since with the closure of Central Railway in sections from 1957 to 1972, the majority of ‘narrow gauge’ workings took place in the Northern Territory. All of the NT Class were transferred north in the 1970s, but not for more than a few years, until 1976.
By 1976 the Northern Railway was closed, leaving NT’s redundant, and with the closure of the vestiges of the 3ft 6ins route from Alice Springs to Maree in 1981, there was nowhere for them to go. Except, there were still trains to haul on the Eyre Peninsula Railway, in what became South Australia’s Port Lincoln Division. The remaining NT’s were joined there by the six newer NJ Class that were delivered to the Central Australia line from 1971.
One of the NT Class locomotives has been rescued and preserved on the Pichi Richi Railway. NT76 was officially withdrawn in 1989, and is now operational on this heritage railway, along with an older sibling from the NSU Class. The Pichi Richi Railway has its headquarters at Quorn – where the NT Class was first fitted with its ‘narrow gauge’ bogies, and operates through the Pichi Richi pass in the Flinders Range down to Port Augusta.
So we know of at least one Barrow-in-Furness built Sulzer diesel engine that is still operational – some 12,000 miles away – and approaching its 60th birthday on the picturesque and dramatic line that was home to the original “Ghan Express”.
Useful & Essential Links
I am indebted to the Pichi Richi Railway, Jeremy Browne, Julian Sharp and Chris Carpenter for additional information, and some excellent images whilst researching this small offering on what you could say was a tenuous connection between Barrow-in-Furness and Alice Springs. The vastness of the Australian interior, and the amazing work of the people who designed, built and completed the railway across the continent was matched by the diesel engines, train crew and everyone involved in operating a railway in such a hostile environment. Thankyou.