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/ Eight years after their introduction in 1981, the high-speed XPTs have become the mainstay of passenger services in NSW. The design is essentially a copy of the British Rail HST (High Speed Train). THE EVOLUTION OF ELECTRIC RAILWAYS Rail enthusiasts may be aware that the NSW State Rail Authority's XPT is very similar in appearance to the British Rail HST which inspired it. However, the British trains are longer, more powerful and sometimes reach 200km/h which is much higher than the XPT's running speed. By BRYAN MAHER The year 1972 ushered in something of a minor railway revolution in Europe. It was the year when Britain first ran the HST or High Speed Trains. These are high speed diesel electric trainsets. At the same time, France was on the way to very fast electric traction which would even- tually culminate in the TGV. In Japan, since 1964, the ShinKansen railway had been providing five trains per hour (day time) on what was then the world's fastest timetable. Their through trains were averaging nearly 200km per hour. The Japanese achieved such high speeds by building dedicated tracks with very gentle curves having a minimum radius of 4 kilometres. In fact, "Shin-Kansen" literally means " new lines" because they are separate from the original tracks and system. PT.17: NSW XPT EXPRESS PASSENGER TRAINS 88 SILICON CHIP British Rail took another approach to the design of very high speed trains. Instead of going for separate tracks with gentle curves, they aimed to use existing tracks which had fairly easy curves anyhow (by Australian standards, at least]. To get very high speed capability, British Rail designed special trains capable of tilting the car body in towards the centre of each curve. The idea is akin to a motorcycle banking in a turn. Trains have been doing this for a long time, of course, with super elevated tracks, whereby the outer track on a curve is higher than the inner track. This shifts the weight of the train to compensate for centrifugal forces when going around curves. By tilting the car body in proportion to the train speed, the train would effectively provide its own super elevation. Engineering problems in the hydraulically-powered tilt-body design proved very stubborn though, which held back the development of the APT or Advanced Passenger Train. In the meantime, British Rail continued with the HST. British Rail HST 42 HST train sets were initially ordered but, due to economic constraints in Britain at the time, this was subsequently cut to 32. The HST consists of a dieselelectric locomotive at each end and eight passenger cars in between. These trains endeared themselves to the travelling public, their high speed and frequent operation providing excellent service between London and Newcastle, Edinburgh, Hull and York. With 18 trains each way daily between Newcastle~ upon-Tyne and London alone, who would want to use their car? Each HST locomotive is powered by a Paxman-Vaienta 1.678MW (2250hp] diesel engine directcoupled to an AC alternator. The output of the alternator is rectified by silicon diodes to provide the DC supply for the four series traction motors. In the first 32 trainsets, the traction motors were supplied by Brush and some sets were extended to 10 cars. GEC Traction supplied the DC The XPT is a departure from normal Australian rail practice in using 4-wheel bogies and a high-speed diesel engine. The engine is a 12-cylinder turbocharged 4-stroke design rated at 1.48MW and has a maximum speed of 1500rpm. motors for a later order of a further 14 trains. In each train, control of the front and rear locomotives is from the driver's cabin at either end, so these trains need never be turned around. On the Newcastle run, the HST trains regularly achieved average speeds of 133km/h, with peak speeds of 170km/h. For this reason the HST trains in England are labelled "Inter City 125" trains, alluding to their 125mph design capability. The high travelling speed and the fast turnaround time at terminal stations enable these British HSTs to move an incredible number of people. British Rail claim that some trains often travel 1700km per day. Considering that 600-700km of this distance is covered at a speed of 170km/h (or more), tJ:\e diesel engines and traction motors certainly earn their keep! The NSW XPT With all these high performance goings-on in other parts of the world, how could Australia not join in? 1981 was a good year for Australian rail. Not only were two major improvements to Melbourne's city and suburban rail systems opened, but in New South Wales the SRA (State Rail Authority] put the first trial XPT or Express Passenger Train on the rails on 24th August. By 6th September, 1981 the trial XPT was running around New South Wales and had set an Australian rail record speed of 183km/h. By 1982, XPTs were in regular service on most NSW main lines. Today they are the backbone of NSW express passenger services, running between Sydney and Armidale, Tamworth, Grafton, Dubbo, Canberra and Albury. Connecting trains and air conditioned coaches feed all branch lines. XPT performance The NSW-SRA XPT trains are modelled on the British Rail HST design but are slightly lower powered. However, as the train set in NSW is usually only five passenger cars plus two locomotives, high speeds are still possible in some areas. The trains, manufactured by Comeng of Granville, Sydney, are available in two versions: the standard version rated at 160km/h maximum and a high-speed version rated at 200km/h maximum. However, in New South Wales MARCH 1989 89 In standard form, the XPT has a locomotive at both ends and five passenger cars. Speeds up to 160km/h are regularly achieved. The XPT presently holds the Australian rail speed record of 183km/h. the considerable number of sharp curves places a limit on the maximum usable speed. For example, on the Blue Mountains, the Hawkesbury Bank between the Hawkesbury River and Cowan, or between Murrurundi and Quirindi, the steep terrain has resulted in sharp curves with the track radius being as tight as 161 metres. Often there are consecutive reverse curves too, which slows things up even further. The 579km run from Sydney to Armidale includes two of the aforementioned sections, so that the 73.9km/h overall average speed with 22 stops is very creditable. Loco specifications Like the British HST, the New South Wales XPT has two diesel electric locomotives, one at each end. Each loco is powered by a Paxman Valenta turbocharged 4-stroke diesel engine. This is rated at 1.480MW (1984hp) at ambient temperatures up to 40°C and any 90 SILICON CHIP elevation up to 1000 metres. The 12 cylinders have a 19.7cm bore and 21.6cm stroke. The engine runs at a relatively high speed compared to other Australian diesels. It idles at 750rpm and has a maximum speed of 1500rpm. Two alternators The diesel engine is direct coupled to two alternators, one for traction and one for auxiliaries. The main alternator and associated silicon rectifiers provide the DC supply for the four Brush traction motors, each a 4-pole DC series type. The traction motors are not mounted within the bogies (as in many other locomotives). Instead, the traction motors are each mounted on the mainframe, with drive to the wheels being via flexible couplings and gear boxes with a 20:65 ratio. Wheel slip and slide detectors are fitted. Each locomotive can provide 84 kilonewtons tractive effort at a 1-hour rating or 77kN continuously. Two locomotives working a 5-car train can provide 240kN starting tractive effort, making for good acceleration. The weight of each locomotive in working trim is 74 tonnes which is really quite light for a diesel of this power. It is built for speed rather than lugging ability. Diesel fuel capacity is 4500 litres. The whole locomotive (except for the driver's cab) is of welded carbon steel, the hody sides being of stressed steel skin. The normal train of five passenger cars with two locomotives weighs a total of 354 tonnes. Bogies The bogies for the locos and cars are designed for high speed running (up to 2ookm/h) with safety and comfort. The suspension system has each axle box attached to a horizontal swing-arm link and maintained in position by a coil spring suspension in parallel with dampers (shock absorbers). The bogie frames carry the car body on a flexicoil pneumatic secondary suspension. The locomotive bogies run on heat-treated rolled-steel monobloc wheels. These are fitted with castiron brake discs in the form of cheek plates and each wheel is fitted with a disc brake caliper. The axles are made of solid forged steel and run iri tapered roller bearings. Brakes The braking system is the Westcode type EP, backed up by the "shadow" emergency brake system. Maximum retardation rate is 0.90 metres per second per second. The disc-brake calipers are air-driven and are fitted with composition brake blocks. Readers may ask why conventional brake blocks are not applied to the running wheels rather than using disc brakes. After all, cast iron brake blocks have been used for a century and are still used today by most freight trains as this method keeps the wheel surfaces clean and in good order. Two disadvantages accrue from the use of cast iron brake blocks. First, repeated stopping results in fast brake block wear and second, cast iron dust flowing from the brake blocks during braking permeates the atmosphere below the train. If this fine conducting dust gets into the traction motors, contactors or control resistances it can lead to electrical breakdowns. For this, reason, non-conducting composition brake blocks are now used on most high-performance trains. But composition brake blocks have the nasty habit of polishing the running surfaces of the wheeltyres. This leads to locomotive wheel slip during acceleration and during braking for both locomotive and carrige wheels. The complete solution invoked by modern train designers is to use composition brake blocks applied via air calipers to cast iron brake discs attached either to the side faces of the running wheels (as per photo) or to inboard discs on the axles. This picture shows the new-high speed hogies used on the XPT. Notice the polished steel cheek plates on both sides of the. running wheels. These function as the train disc brakes. Auxiliaries The auxiliary alternator is direct-driven by the loco's diesel engine and provides a 3-phase AC supply, regulated to 415 volts at any engine speed in the working range. This power is used for all train electrical equipment, such as squirrel-cage induction motors for air conditioning and ventilation, fluorescent lighting and cooking in the buffet car. In addition, the engine compartments and traction motors are force-ventilated with filtered air, while the driver's compartments at each end of the train are airconditioned. To allow for the sometimes very dusty atmosphere of western and southern NSW, the induced air supply for the diesel engine cylinders needs to be doubly filtered otherwise engine wear would be a real problem. British HSTs don't have to contend with either the dust or the high temperatures experienced by the Australian XPT. The manufacturers have provided for easy maintenance and replacement of components by building the driver's cab, electrical This picture shows the driver's winds_creen after testing with a large projectile at 240km/h. The heavy laminated glass is fractured hut no penetration has occurred. MARCH 1989 91 View inside the driver's cabin, showing all the major controls for the XPT. The cabin is air-conditioned to ensure comfortable conditions for long-distance high-speed operation. control cabinet, diesel engine/alternators, engine cooling radiator and the brake/air compressor gear as separate modules. These can all be easily removed and replaced so the loco need not be out of service for long periods. For fire safety, the electrical control and equipment ea binet and the diesel engine/alternator section are provided with automatic fire extinguishing equipment. Coach interiors The lightweight cars perform beautifully and are very well accepted by the travelling public. Normally fitted with groups of four fixed seats on each side of the centre aisle, the wide windows and air conditioning give a pleasant and enjoyable travelling experience. Alternative seating offered by the manufacturer includes groups of three seats, or recliners and/or rotating comfort seats, with or without tables. Individual reading lights complement the car fluorescent lighting. Toilets are provided at each end of each car with hot and cold water at the wash basins. 92 SILICON CHIP The buffet occupies half a car and is fully fitted with electric equipment for preparing meals. A guard's compartment is provided at each end of the train. Driver's cab The driver's cab is a resiliently mounted, glass-reinforced plastic module, resulting in effective isolation of the driver from the noise, heat and vibration of the diesel engine. The nose cone contains two large anti-collision buttresses to protect the driver in the event of frontal impact. To allow safe operation at 160 or 200km/h it is essential that the front end of the driver's cab be proof against accidental strike at speed by a bird or any object. (Occasionally rocks, bottles and other rubbish may fall or be thrown onto a train from overhead bridges and tunnel entrances). To ensure driver confidence and safety, the train manufacturer, Comeng, constructed a full-size timber mock-up of the driver's cab and tested the driver's window with missiles projected at 240km/h. The driver's cab is fitted with central controls plus meters for air pressure, motor current and train speed. To ensure a clear view, the front window is fitted with a heater-demister, windscreen wiper and washer. Comparing the XPT and HST Fundamentally, the XPT and British HST are quite similar although the former runs on radically different bogies to cope with the much rougher Australian tracks. The British, with their much larger population, can afford to provide more money for track straightening as each line carries many more trains. Furthermore, nowhere in the British system are mountains encountered as in Australia. These facts prevent the NSW XPTs from ever matching the high average speeds achieved in Britain. ~ Acknowledgement: thanks to Comeng of Granville, Sydney and the NSW-SRA for their assistance and photos.