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THE BIG PULL.. AND PUSH

1st January 2004, Page 40
1st January 2004
Page 40
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Page 40, 1st January 2004 — THE BIG PULL.. AND PUSH
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Which of the following most accurately describes the problem?

CM'S Aussie correspondent Steve Brooks has gone walkabout to track down a 400

tonne Kenvvorth roadtrain. They don't come bigger, or tougher, than this.

The vast expanse of Australia's Northern Territory known as the Tanami is definitely not for the fainthearted, especially when it comes to running trucks. It's hot, hostile and for the most part just plain hard. But while it might look like just another piece of scorched,sterile outback the Tanami has a hidden secret —gold!

And Down Under, wherever there's gold you'll find entire communities devoted to getting the precious metal out of the ground. In the Tanami's case that means communities like those serving The Granites and Groundrush mines, rich outposts of the expansive Newmont Mining Corporation about 550km north-west of Alice Springs, Nothing comes easy in the Tanami, even for big outfits like Newmont. For instance, when you're extracting just 0.18 ounces (fig) of gold from every tonne of ore cracked from the ground, simply hauling enough rock to the processing plant to justify the massive investment in people, plant and equipment is a serious undertaking.

That's where Bulkhaul and its remarkable six-trailer roadtrains come in. Indeed, so impressive (and critical) are these huge haulers that Newmont's own PR blurb proudly proclaims:'Ore is transported to The Granites using the largest roadtrains in the world ...the 'train carries an average payload of 275 tonnes.'

Naturally there's more to Bulkhaul's roadtrains than their size (97m from nose to tail) or the tonnages they tote. Indeed, the body-andsix' combinations are the result of an engineering evolution that's set new parameters in productivity and performance for hauling ore in remote areas of Australia. Bulkhaul has been working in and around The Granites for more than 10 years, starting with conventional triple trailer combinations, before gradually advancing to 'body-andthree' and then 'body-and-four' rip. Up front Autocar,White and Western Star have all had a spell in the Tan arni sun, but nowadays Kenworth rules.

Despite those different marques one engine manufacturer Cummins— has remained the dominant power provider, particularly with its industrial 18.9-litre K-Series block. Originally developed for heavy mining machinery and excavator applications, over the years the K-series has endeared itself to Aussie roadtrain operators, especially those looking for a long engine life ahead of any concerns about weight over the front axle or the inherent lack of an engine brake. While the K-Series has proved a trusty servant for Bulkhaul, the search for evergreater productivity in recent years has seen the company push the roadtrain concept even further.Today it's running tri-drive Kenworth C510 body trucks, powered primarily by Cummins' QSK19 engines,hauling six side-tipping trailers, including one driven by its own 15-litre Signature engine! But we're getting a little ahead of ourselves.

Until some five years ago, Bulkhaul's operation at The Granites was well-served by 'bodyand-foue rigs punched by the aforementioned mechanically governed K-Series engines with 600hp and around 2,000Nm of torque on tap. Back then payloads of 200 tonnes and more were normal. and it was widely considered that the K-Series was doing a good job under tough conditions, with each notching 10,000-12,000 hours (up to two years) on operations before requiring a major overhaul.

Indeed. given the exceptional weights and ambient summer temperatures—commonly up to 50°C —plus round-the-clock operation on an 80km round trip from mine site to crushing plant, it wasn't hard to see why BulkhauI was pleased with the performance and durability of the big bore Cummins.

However, nothing stands still in transport. Prodded by the need for even greater operating efficiency and engine life, and spurred on by the availability of Cummins' advanced QSK19 engine (the K-Series' natural successor) Kenworth subsequently engineered and built the highly specialised C510 model. Designed specifically to withstand the heat and hardships ofThe Granites, the '510 is a classic homegrown Down-Under product from Kenworth's factory in Bayswater,Victoria.

Boasting such unique features as twin 1.23m' radiators fitted in series (one for the engine, the other for the after-cooling system) the C510 became the first truck to win a prestigious engineering award from the Society of Automotive Engineers.

It employs a hydraulically driven cooling fan that operates independently of the engine and idles continually at 600rpm until coolant temperature rises.leading to an increase in fan speed to achieve the required airflow. Surrounding the QSK is a bonnet that's almost half a metre longer than the standard C500 (and C501). with a dual-skin firewall to divert heat away from the cab and driverAnd with a weight over the front axle of around 7.5 tonnes, twin steering boxes are fitted. According to Jim Cooper, boss of 13ulkhaul's parent company GulfTransport, the C510 "is the finest truck ever built forAustralian conditions, and a real tribute to the skill of Kenworth and its engineering people".

While the QSK19 can be rated at up to 750hp, bringing with it a mind-numbing 3.050Nm of torque, driveline limitations restrict the Bulkhaul units to 600hp and a 'mere' 2,000Nm of torque at 1,300 rpm.Th us in pure performance terms the QSK delivers the same output as its mechanically-governed predecessor—but in most respects, that's where the similarities end.

The first QSK-powered C510 entered service at The Granites in late 1997, followed soon after by two more, all set up as tri-drive body trucks pulling four side-tipping trailers and driving through Eaton RTLO-22918 18-speed single-overdrive transmissions into heavy-duty Mentor drive axles.

While the C510s have been models of reliability virtually from day one. Bulkhaul wasn't about to leave it at that. It was obvious that pushing payloads even higher by simply adding one, or even two, more trailers,was impractical,purely on the grounds that the impact on driveline life would be hon-ific.

The trump card has been the poweredtrailer: a concept that promised the ability to haul up to six trailers and gross weights of 400 tonnes or more, and with demonstrable reductions in operating costs without hitting engine or drivehne life.

Like most good ideas, the powered trailer is a relatively straightforward engineering exercise. In Bulkhaul's operation atThe Granites.the sixtrailer combination was achieved by inserting a B-double between the second and third trailers in a four-trailer combination.

The rear trailer in the B-double pair is the powered unit, and in the initial installation a 400hp Cummins M11 wasmounted amidships between the trailer chassis rails and coupled to anAllison six-speed automatic transmission (configured to operate as a five-speed) feeding into Mentor's heavy-duty RT52-380 tandem-drive assembly. The radiator for the engine sits in its own cradle behind the tipping body of the trailer.

Smooth and simple in operation. the powered trailer system is surprisingly simple and stunningly smooth. The second engine is switched on and off by a standard key-operated ignition switch mounted in a secure box attached to the chassis rails of the powered trailer. It is only started when the combination is loaded. In the cab, a panel under the centre of the dash houses a hand throttle for the trailer engine, a selection panel for engaging the Allison auto, and instrumentation including a tacho and warning lights for coolant. diffs and transmission temperatures.

To pull away you simply throttle the trailer engine up to around 1,000rpm prior to lift off, and drive the truck normally before increasing trailer engine speed to around 1,500rpm as the combination picks up pace on its way to a maximum speed ofjust under 70km/h. On downshifts through the truck's transmission, use the hand throttle to marginally peel back trailer engine speed as the shift is made.

Overall,it's easy to understand how Bulkhaul drivers have quickly come to grips with the driven trailer, while from inside the cab lift-offs and general performance of the combined 1,000hp output are remarkably smooth.Also, noise levels on the inside are exceptionally low. At the unloading point, a tickle on the powered trailer's throttle helps the massive combination to crawl forward as it discharges its load, greatly easing the workload on the C510's clutch and driveline.

The C510 -pull-andpushrig runs on 50 wheels and is close to 97m long. From a distance it looks like a great mechanical centipede stoked to the gills on steroids.

The first of the 'body and six' combinations started work at The Granites in 2000 and almost immediately the results justified Bulkhaul's investment. Payloads jumped from around 200 to at least 270 tonnes. while the 'push' of the extra engine has allowed the outfit to run over the steepest section of the access road some two gears higher than the previous body-and-four combinations.There's also been a 10% improvement A Early powered trailers were powered by Cummins Ml is but these have recently been superseded by 15-litre ISX engines rated at 400hp in fuel efficiency on a cost per tonne/km basis, compared with existing body-and-four rigs.

Ironically, the very first six-trailer outfit to start working at The Granites wasn't fronted by a Kenworth C510 with a QSK19 engine; instead it had a relatively standard Kenworth C501 with a similarly "normal Cummins Signature 600.The move was prompted by simple economics-just as the six-trailer side-tipping roadtrain carries more payload,and requires significantly less capital outlay than a highly specialised off-road rear dump truck, so the C501 with a Signature 600 underneath was considerably cheaper than a custom-made C510 with its QSK power plant.

Today Bulkhaul operates no less than seven tri-drive trucks between The Granites and Groundrush sites, and all but one of them haul six trailers including a powered one. Currently. four of them are C510s with a QSK19 under the snout; the remainder are C50 Is with Signature 600s under the beak. Additionally.400hp 15-litre ISX engines have replaced the original MI Is in the powered trailers. with their power now fed into a tridrive assembly (instead of a tandem) while the lead trailer in the centre B-double group is now a quad-axle layout to enhance stability.

Despite the changes, the tare weight of each rig is still an impressive 120 tonnes and gri train weights regularly exceed 400 tonnes and that's running in a hot desert region./ they're kept busythe demand for ore ca upwards of 10,000 tonnes a day.

However, the biggest lesson to be learn from the Tanami experience is that there': simply no alternative to cubic capacity wt. weights are whopping and demands are d structive,and in this regard the cost-effect ness and durability of the QSK19 engines been remarkable.

Seven days a week Operating in two. 12-hour shifts. seven days a week, the trucks average around 240,000km (and approximately 6,000 et hours) annually. But according to Wade Russell, Bulkhaul's depot manager at T Granites, the first of the big bore Cumn engines notched up an incredible 27,001 hours more than four years in bodyfour, and body-and-six configuration bt being overhauled.

Not only that:from day one the QSK have required just 13 litres of top-up oi per month between service intervals, "and they've maintained that all the WE through," says Russell, who reports tha in the QSKs is changed every 250 hour "It doesn't matter whether they're rt fling loaded or empty, the engines are u heavy load all the time," Russell points "and for jobs like this, you need big cut. It's really as simple as that."


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