Equipment Type

Western Star 6900XD Proves a Real Rocker

Western Star says its 40-ton dump truck is a lower-cost alternative to traditional haul trucks, and time will tell if it's as tough and long-lasting. The extra-heavy-duty vehicle was introduced in 2008 and is based on a 6900XD with a commercial-style on-road cab. It includes a standardized power train and an integrated dump box.

November 01, 2009
Western Star 6900XD haul truck

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Off-road dumper rides rather smoothly, even empty, and is very easy to drive. Just remember that it's top heavy with 40 tons aboard and you're good to go.

J&J dump body on Western Star

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Stout J&J body is made of Hardox steel, and hoist tips it in 25 seconds at 1,000-rpm engine speed, according to specs. Tailgate stays stationary during dumping.
Western Star 6900XD haul truck

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Cab is from 4900 series and its gauges and controls are similar. Controls include switches for Jake Brake and a lever for the Allison's hydraulic retarder.

Specifications

Truck: Western Star 6900XD 40-Ton Dump, conventional-cab off-road 6×4 hauler, GVW 138,000 pounds

Engine: 14-liter Detroit Diesel Series 60, Tier 3 emissions certified, 500 hp @ 1,800 rpm, 1,550 lbs.-ft. @ 1,350 rpm, with Jake Brake

Transmission: 6-speed Allison 4500RDS fully automatic, with hydraulic retarder

Front axle: 28,000-lb Sisu-Fabco FSND 12G on flat-leaf springs

Rear axles: 110,000-lb AxleTech SPRC 1927 double-reduction, 11.23:1 overall ratio

Brakes: Meritor S-cam drum

Tires & wheels: Michelin 14R25 on 25×10-inch compactor rims and 25-inch 12-spoke centers

Body: J&J Dyna-Hauler/OTR, Hardox 400 and 450 steel construction, capacity 40 U.S. tons, 24 cu. yds. struck, 30 heaped

Western Star says its 40-ton dump truck is a lower-cost alternative to traditional haul trucks, and time will tell if it's as tough and long-lasting. The extra-heavy-duty vehicle was introduced in 2008 and is based on a 6900XD with a commercial-style on-road cab. It includes a standardized power train and an integrated dump box.

Aimed at quarry and dirt-haul operations with well-maintained roads, the three-axle 6900XD can carry the same loads as 35- to 40-ton rigid and articulated dump trucks but uses 35 percent less fuel, says Western Star, since 2000 a part of the Freightliner family. Fuel consumption of 7.13 gallons per hour has been recorded on hauls of more than 12 miles, representatives said. The truck's stated top speed is 43 mph, though it feels like it could go faster.

But there wasn't room for fast truckin' at the site of this recent demonstration, a rock quarry operated by Meckley's Limestone Products about an hour north of Harrisburg, Pa. The demo was staged in a corner that included an active pit and a climb up a quarter-mile grade that was as steep as 9 percent in one spot. I drove the 'Star maybe a dozen times up and down that grade, both empty and loaded, and found that it's pretty easy to handle.

The truck's J&J steel dump body is 128 inches wide, so the truck is too beamy for legal on-highway travel except aboard a flagged lowboy, which is how it got here. But it's a couple of feet narrower than the Cat and Euclid trucks that appeared briefly during the day. Compared to on/off-highway dump trucks, the 6900XD felt almost ponderous when loaded — after all, gross weight was close to the 138,000-pound ratings of its three axles — but rather agile when empty. (It competes with the Cat 770 and Terex TR34 and TR40.)

The 500-horse Detroit Series 60 propelled it well, and the 4500 series Allison 6-speed automatic smoothly sent power to the ground. While climbing the grade, the engine usually hovered at 1,500 to 1,600 rpm, right about at its "sweet spot" for power and economy, but revved to 2,000 rpm in the first few gears when starting the truck from a dead stop on the steepest part of the grade. The Detroit was an off-road EPA Tier 3 engine with no particulate filter, so there is some visible smoke. But it was nothing like the coal-black clouds emitted by diesels of yore.

AxleTech rear axles are double-reduction types that, with differential and hub gears, provide an overall ratio of 11.23 to 1, which is needed to move the truck loaded or empty. The Chalmers mechanical rear suspension rode fairly well, and the cab's rear is air mounted; that and the air-sprung driver's seat filtered out most shock.

Inside the tall cab it's fairly quiet, and any driver should be pleased with the appointments. Seat upholstery was a tough-looking but comfortable fabric, and most steel surfaces were covered with padded panels. The cab is wide enough to seat three people, and this demo truck had a two-man bench next to the driver's perch. Real-world work trucks would dispense with the extra seating except for training, but new drivers should need very little of that.

Instrument-wise, the usual speedometer and tachometer were flanked by an electronic display panel that housed warning lights, while an array of small analog gauges showed what was happening in the engine, transmission and axles. On the dash were rocker switches for everything that needed to be switched on or off, including the Jacobs Engine Brake. There was also an almost dainty lever to run the Allison's retarder.

So the 'Star has three means of deceleration: the Jake, the retarder and the service brakes. I list them in that order because that's how they're best used. On that steep downgrade, leaving the Allison in Drive would let the Jake cut off at 10 mph, but punching the autotranny into 1st gear would make the Jake slow the truck to about 4 mph. The Allison's retarder then almost stopped the truck, and could bring it to a halt on the level. So I seldom needed to step on the air-brake treadle, and linings should last a long time if the truck's driven that way.

The truck was painted bright yellow, just like any haul truck, but will it truly do the job and last as long as the Cats and Ukes of the world? Laverne Smeltz, who manages Meckley's fleet, thought so, and was considering the purchase of two of them. He said a 6900XD dump would cost "about half" what a comparable Cat does. And it should be much cheaper and easier to maintain because so many parts, such as the drum brakes and the Allison automatic, come from on/off-road trucks and can be bought in the aftermarket. So operators aren't confined to specialty parts from the haul-truck's builder.

The 6900XD is not unique, however, as it does face at least one similar model, Kenworth's C500, though Smeltz said no one from KW had ever called on him. Late next year Cat itself will have a new, similar sized truck, probably based on the International 5000i Paystar, a vehicle that's among the fruits of the recently inked alliance between Cat and Navistar International. So as the economy improves, watch your local quarry or big excavation site for signs of more competition among builders of these specialty vehicles.

 

Specifications

Truck: Western Star 6900XD 40-Ton Dump, conventional-cab off-road 6×4 hauler, GVW 138,000 pounds

Engine: 14-liter Detroit Diesel Series 60, Tier 3 emissions certified, 500 hp @ 1,800 rpm, 1,550 lbs.-ft. @ 1,350 rpm, with Jake Brake

Transmission: 6-speed Allison 4500RDS fully automatic, with hydraulic retarder

Front axle: 28,000-lb Sisu-Fabco FSND 12G on flat-leaf springs

Rear axles: 110,000-lb AxleTech SPRC 1927 double-reduction, 11.23:1 overall ratio

Brakes: Meritor S-cam drum

Tires & wheels: Michelin 14R25 on 25×10-inch compactor rims and 25-inch 12-spoke centers

Body: J&J Dyna-Hauler/OTR, Hardox 400 and 450 steel construction, capacity 40 U.S. tons, 24 cu. yds. struck, 30 heaped

 
 

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