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THE EVOLUTION OF ELECTRIC RAILWAYS The locos, rolling stock, tracks, plant and methods used by the Pilbara iron ore railways are the most advanced in Australia. The efficiencies attained with their very large "unit" trains are far above those acbieved on State-owned rail systems. By BRYAN MAHER Last episode we saw how the longest and heaviest trains in Australia, many of 31,000 tonnes, run on three privately owned iron ore railways in the Pilbara region of Western Australia. Hauling these- trains are the most powerful diesel electric locomotives in the country. In harsh, hot, dusty conditions these huge trains run great distances at speeds up to B0km/h, PT.26: THE PILBARA IRON ORE RAILWAYS (2) 82 SILICON CHIP THIS PHOTO SHOWS HAMERSLEY'S enormous wagon yard and workshop facilities at the Seven Mile Yard near the port of Dampier in the far north of Australia. The company owns 2470 ore wagons and 47 large diesel electric locomotives. Keeping all this rolling stock running reliably is a big operation in itself. sustained for hour after hour. The locomotives, rolling stock and tracks are subjected to very high loadings as the emphasis is always on maximising throughput. Given the environment, the isolation dictates that each of the three railway companies provides its own facilities, including workshops for heavy engineering repairs and maintenance. The big supercharged diesel engines are particularly heavy at around 180 tonnes, resulting in high loadings of 29.9 tonnes per axle. Mostly the locomotives are used as triple headers to pull the trains while triple bankers are often added at the rear on heavy uphill sections. These high loco weights plus the heavy wagons used require the strongest possible rails and strong sleepers with solid track foundation. Hamersley Iron presently owns and operates 47 mainline diesel electric Co-Co locomotives in the 2.7MW class. The railway headquarters are at the 46-track Seven Mile Yard, 11km east of Dampier. Here are located train holding, fuelling and storage facilities, heavy workshops. the central train controller and administration. Diesel engine loading All locos have to work very hard, whether they are pulling loaded ore trains to port or empty trains back to the mines. For the return journey from Dampier, the empty trains weigh 5400 tonnes which is a very heavy load as far as conventional railways are concerned. On the uphill drag to the mines, the locos work at full throttle for 270km of the 288km distance from Dampier to Mt. Tom Price, on grades up to 1.5%. Then with diesel engines idling, full regenerative brakes are used over the whole 98km downhill run to Paraburdoo. Loaded trains call for the diesel engines to run at full throttle for 3½ hours ascending from Paraburdoo to Mt. Tom Price. From there on to Dampier the train is on full regenerative brakes all the way except for an 18km uphill stretch at full throttle. So even when the diesel engines are idling, the traction motors are still heavily loaded because full regenerative braking means the same motor current as full traction power. When capital investment is taken into account, the most cost-effective way to use any machinery is to run on full load all the time. Except in the Pilbara, this is almost never done on other Australian railways. All trains in the eastern states give their traction motors a onehour rating at full current, with continuous rating at a lower figure, typically 92 % . However, on the Pilbara ore lines and on Hamersley trains in particular, traction motors carry full current 100% of the time for 7 or 8 hours almost without a break. On DECEMBER 1989 83 Locomotive maintenance AT THE PORT OF DAMPIER the ore wagons are unloaded in a huge rotary dumper which handles two wagons at a time, without uncoupling them from the train. This photo shows the hydraulic wagon positioner which works on rails outside the main tracks. To withstand such heavy and consistent use, these diesel electric locos require regular and thorough maintenance to their engines, traction motors, wheel sets and bearings. The workshops at Seven Mile comprise a loco running shed (trip service) and heavy maintenance and wagon repair sections. After each run locomotives are inspected, refuelled, their sand boxes filled, and then rescheduled. Usually this service is performed on three locos together as a triplehead set. Lubricants and treated coolant water are topped up and safety features checked. At fortnightly intervals air filters are cleaned and oil and water samples are tested. Lubricating oil filters are tested by measuring their hydraulic impedance by the oil pressure drop across them. Traction motor covers are removed, so that the commutators and brushes can be inspected. At 30,000km intervals, which amounts to just 40 round trips, every locomotive is thoroughly checked and adjusted. As required, components such as turbochargers, pumps or fittings are changed at the 240,000km service. Diesel engines are normally changed and overhauled at the 1,000,000km interval. At all times computer programs check measurements and data to predict any need for changes or repairs. Diesel rebuilds AERIAL VIEW OF THE ROTARY DUMPER facility at Dampier. It takes about four hours to unload a typical 30,000-tonne train. empty trains the percentage is only slightly less. The timetable shows one particular train leaving Paraburdoo mine at 4am and travelling non-stop at continuous full motor current (either full traction or full regenerative braking) until 10:30am. 84 SILICON CHIP After a 12-minute halt at a crossing loop this train then resumed full motor current until arrival at the Seven Mile Yard at 11.20am. Apart from that short crossing loop halt, the traction motors were on 100% full load current all the time. Diesel engines are completely rebuilt in the heavy engineering bays. Our photo indicates the enormous size of these V16 Alco designed engines. Alco have favoured the 4-stroke principle while the latest EMD SD50S super series have turned to 2-stroke diesels to produce more power from the same engine weight. One heavy maintenance bay has shop. floors raised to loco running board level to facilitate access to engines. The shop is provided with two 75-tonne capacity overhead travelling cranes with 15-tonne auxiliary hoists, plus bridge and column cranes. Oil, water, air etc are laid on to automatic dispensing apparatus. The six 448kW DC traction motors on each locomotive are the most critical components. Mounted down in the bogies they are the electrical components most subject to dirt and vibration. And the motors run close to the ballast and rails which in summer are at sustained high temperatures, up to 74°C. When major repairs are needed, the motors are removed, disassembled and serviced. Armature rewinding is about the only work sent to outside contractors in the cities. All other electrical repairs, including complete bogie rebuilds, are done in Hamersley's Seven Mile shops. Load testing Before and after diesel engine overhauls, the direct coupled traction alternator electrical circuit is disconnected from the traction motors and fed to a bank of fan cooled 3MW resistors as a dummy load. The diesel engine and alternator HAMERSLEY LOCOS ARE BASED ON AMERICAN designs but have been considerably upgraded to cope with the rigorous conditions in the Pilbara and the requirement for full throttle operation for up to eight hours at a time. This unit is rated at 2.9 megawatts (3900hp). are then run at full speed and the power dissipated in the resistors is measured. This is the most valid direct measurement of diesel engine power output and is a critical full load test for the alternator. Such testing is essential when the -consequences of a breakdown on the line are considered. Just imagine how expensive it would be if a 31,000 tonne train broke down on the single track line hundreds of kilometres from anywhere. Heavy wagons Now let's consider the ore wagons on Australia's longest trains. These are all eight wheelers, weighing 120-128 tonnes fully loaded, meaning each axle carries 30-32 tonnes. Many of these wagons are made by Comeng of Granville, Sydney. They are 9.34m long, 3.31m high and 3.29m wide and weigh 20.6 tonnes empty. Hamersley has 2470 of these ore wagons. To service all their ore wagons, Hamersley has a continuous main- tenance program. A trackmobile brings groups of 12 wagons into the shop where they are speedily but thoroughly serviced and lubricated, with wheelsets being changed where necessary. Up to 24 wagons are serviced each day. The brake gear is changed every 5 or 8 years. All wagons are monitored frequently in the running yard to detect any needed repairs. Wheel profiling For longest wheel and rail life and least running friction, optimum wheel profile should be maintained. Wheel tyres sometimes wear more at centre tread whereas the correct slightly tapered shape is needed for least friction on curves and true running on tangential track. Should a wheel ever drag due to sticking brakes the tyre quickly develops heat-hardened flats which make lathe turning difficult. Hamersley's Seven Mile yard includes mills and lathes for restoring wheelsets of locos and wagons to optimum profile. The lathes are situated both above ground and below droptrack pits. DECEMBER1989 85 THE PILBARA RAILWAY TRACKS are continuous ribbons of steel, from mine to the port of Dampier. The rails are laid in 400 metre lengths, before being welded. Special trains are needed to carry such long loads to where they are needed. Rotary dumping Whereas most eastern states empty their coal wagons through hopper doors in the floors, this method is unsatisfactory in the case of iron ore. Iron ore has a much higher density than coal and the extra weight would mean damaged hopper doors if the ore were dumped into this type of wagon. Therefore, the ore wagons have solid steel bottoms, sides and ends, all fully welded. Each truck must be tipped bodily to dump the load. This is done in a rotary dumper, a very large cylindrical rotating frame containing a rail track section. In operation, a fully loaded train is hauled through this cylindrical frame, moving a distance of two wagon lengths at a time. As pairs of wagons pass into the cylindrical frame, the whole cylinder - rail section, wagons and all - rotates to dump the 212 tonnes of iron ore into an underground hopper. During this process, the wagons are held on the rails within the dumper as it rotates. Since the dumper rotates on the same axis as the train drawbar couplings, there is no need to uncouple the wagons for dumping. Thus, the train is never broken. 86 SILICON CHIP The rotary dumper itself is a cylinder as big as a small house. It measures approximately 12 metres in diameter and 19 metres long, with each end having an opening the size of a railway tunnel through which the train passes. The train is fed through the dumper by a hydraulically operated car positioner which runs on a wide track parallel to the trainline. The positioner shunts back and forth as demanded by the dumper, each time pushing the train along the track by attachment at the wagon sides. The rate of unloading is 7000 tonnes per hour. On that basis, it takes about four hours to unload ·a typkal train. Heavy track The Pilbara iron ore lines are notable not only for the very high axle loading of their locomotives but also for all their rolling stock. As noted above, the axle loading for each and every ore wagon is 30-32 tonnes. This means that very heavy track is required. The iron ore lines in WA began using 59kg/m rail in the 1960s and at that time it was as heavy as anywhere in Australia. This was progressively replaced after 10 years use with 68kg/m headhardened BHP rail which is laid in 400-metre lengths. After laying, these lengths were welded to form unbroken rails 382km long. There's no clickety-clack on these railways. You might well ask how continuously welded track does not seriously distort due to expansion and contraction in the wide temperature range of the Pilbara. The answer is that it is firmly held in place by the concrete sleepers and heavy track ballasting. By 1986, all Hamersley track sleepers had been changed to concrete. Straight track sections can wear unevenly because at a constant high forward speed, wagons tend to set up a transverse oscillation. Corrective measures include rail grinding in selected places to restore the rail profile, the use of BHP head-hardened rail, and the maintenance of optimum wheel tyre cross-section. The track is aligned by laser survey and the Plasser track dynamics and geometry car which takes measurements in both horizontal and vertical directions. Accurate straight rail is important in reducing flange-rail friction on long heavy trains. Steel sleepers In contrast to the Hamersley Iron Railway, the Mt. Newman Railway has used thousands of steel sleepers, pressed from heavy plate by the BHP company. To allow for signalling track circuits, patented rail insulating pads and track fasteners hold the rails to the sleepers. Bridges Hamersley has many river and creek crossings. In fact, there are 20 steel bridges and 442 culverts. The longest river crossing is at the Fortescue River on a causeway of 30 culverts, each 3.66m in diameter. The longest steel bridge in WA is Hamersley's Spring Creek bridge between Paraburdoo and Mt. Tom Price. The span of 165m is 46m high above the (usually dry) creek bed. This 878 tonne bridge was built in 42 days. Though for most of the year there is no water at all in these creek THIS MASSIVE MACHINE WAS USED in Hamersley's extensive program to change all railway sleepers to concrete types. The machine spreads the rails, lifts out the old sleepers, installs the new concrete units and then repositions the rails, all without cutting. beds, during cyclones they are subject to ·flash flooding due to extremely heavy downpours. This means that tracks, bridges and approaches must be built to withstand cyclonic winds and the tremendous destructive forces of occasional flooding. Signals and communications A 22kV power line provides 240V supply for CTC signalling over the whole route. Also carried on the cyclone-proof power line poles are conductors for the CTC telemetry system, carrier trunk phone lines and direct telephone connections from every signal to central control. Between the power line above and the communications line below is strung an aerial earth wire which acts as a 50Hz shield. This construction is unique in Australia. The telemetry system at 28kHz and 12kHz links the 25 signal relay rooms along the track. The 200 signals are multiple aspect colour light displays for speed indication and control, with route signalling near crossing loops and yards. Track point operation is by 24V DC motors in remote areas and by 110V AC trailable point motors in the main Seven Mile yard at Dampier. central control room. Radio messages then warn the train driver. Should any equipment drag from running trains, dragging equipment detectors (DEDs) inform central controllers. Communications Communication between all trains, track maintenance and support staff is maintained using 9 UHF radio channels in the 480/481 MHz band. Trackside radio repeaters are linked by a 6. 7GHz 960 channel microwave system involving 10 microwave repeater stations over the 386km distance. Hamersley leases 60 channels of this microwave system. As well as supporting the UHF repeaters, the microwave system provides signal telemetry system backup, voice, facsimile and computer communications. ~ HBDs and DEDs Hot bearings on running trains are measured by hot box detectors (HBDs) mounted at sleeper level. Any hot wheel bearings on a passing train will automatically trigger the track-mounted temperature detector, raising an alarm in the Acknowledgements Our thanks to Hamersley Iron and Mt. Newman railways, and Comeng of Granville, NSW for data, photos, drawings and permission to publish. DECEMBER1989 87