Equipment Type

Volvo VNX Heavy Hauler Is Smooth and Steady

Specialized tractor expands Volvo’s Class 8 lineup to more customers

July 21, 2014

Volvo Trucks has a strong but comfortable way to move heavy loads: the VNX, a model that combines the frame of the VHD vocational truck with the cab and interior of VN highway tractors. The VNX was introduced early last year and went into production months later. The first ones went to dealers, and Construction Equipment had the opportunity to drive this one earlier this year. Heavy haul tractors do not comprise a big segment of the market, but Volvo wanted to expand its offerings into more applications.

Heavy haul tractors pull some heavy loads. The VNX is designed for gross combination weights of as much as 200,000 pounds. This VNX is approved for up to 125,000 because it had the I-Shift automated mechanical transmission, and the builder’s engineers are being cautious about what applications it’ll be sold to. For this drive, GCW was a mere 77,780 pounds with a full fuel tank as our load was composed of pallets of decorative cast blocks on a spread-axle flatbed trailer.

Volvo VNX Test Set

Truck: Volvo VNX64T-300, 6x4 daycab heavy-haul tractor, BBC 123 in., GVW 62,000 lb., GCW 125,000 lb., tare weight 19,353 lb.

Engine: Volvo D16, 16.1 liters (984 cu. in.), 600 hp @ 2,000 rpm, 2,050 lb.-ft. @ 1,100 rpm, w/ engine brake

Transmission: Volvo ATO3112D I-Shift automated mechanical, 12-speed w/ 0.78 to 1 overdrive 12th, w/ 17-in. Sachs organic single-face automated clutch

Front axle: 20,000-lb. Volvo VF20 w/ TRW THP60 dual integral power steering, on 20,000-lb. parabolic leafs

Rear axles: 46,000-lb. Meritor RT46-164EH w/ 3.56 ratio, on 46,000-lb. Hendrickson Primaax EX air-ride

Wheelbase: 190 in.

Brakes: Bendix Spicer S-cam, 16.5x6-in. front, 16.5x7-in. rear, w/ Bendix 6-channel ABS

Tires, wheels: Bridgestone M844 425/65R22.5 front, M726EL 11R24.5 rear, on Alcoa polished aluminum discs

Fuel tanks: Dual polished aluminum, 100-gal. left, 75-gal. right

DEF tank: 18.5-gal. polyplastic, left side

Fifth wheel: SAF-Holland FW35 air slide

Trailer: 48-ft. East BST aluminum flatbed

You may or may not agree when I say that Volvo styled the VNX right. It has a high stance and blocky lines that visually declare it to be a serious work truck. Wide wheels and tires on the steer axle, and the polished aluminum headache rack, underscore that. Yet the I-Shift transmission made the rig almost as easy as driving a long limousine.

Aside from looks and easy-does-it driving, the VNX’s attributes include plenty of power, steady steering, a smooth ride, and a driver-spoiling interior. I observed these on a jaunt through the hills near Asheville, in western North Carolina. We picked up the rig at the site of Volvo Construction Equipment’s old testing site nearby.

Wade Long, director for product marketing, said the VNX combines the frame and high stance of Volvo’s vocational model, the VHD, with the highway comfort of the VNL. Its forward mainframe sits 10 inches above the front axle’s centerline to provide good off-road clearance, and the chassis stands 4 inches higher than a VN; it looks just right with tall wheels and tires. But the cab is outfitted like a VN, so drivers are well housed for runs longer than what the VHD might be dispatched on. This tractor was a daycab, but two sleeper options are available.

The VNX comes with just one engine, the big 16.1-liter D16. This one was rated at 600 horsepower and 2,050 lb.-ft., and we never lacked for go-ability. I asked why a Cummins ISX15 wasn’t an option, as in the VNL.

“That would take away the efficiency of the Volvo integrated powertrain,” Long said, noting that the I-Shift can be had only with a Volvo engine. Using a manual gearbox would be less efficient, even if it’s necessary for higher gross-weight ratings of the VNX, but when a rig exceeds 100 tons its fuel economy becomes less important than durability.

Long had mapped a route, and for part of our travels we used “Future Interstate 26,” which apparently lacks some design details to merit full federal I-road status but sure seemed like a freeway to me. Here we put the VNX’s big D16 to a series of pulling tests. On upgrades of 6 percent and more, road speed dropped as low as 30 mph at 1,300 rpm. This I-Shift had the premium selector with an E/P (economy/performance) button, and when I punched it into P, revs climbed to 1,700 and we accelerated on at least one hill. Default is economy, but with the performance mode chosen before climbs began, the 6-percenters could be taken closer to 50 mph and 1,600 to 1,700 rpm.

It was a pleasantly cool day and the engine ran cool, at around 190F; the fan kicked in at 192 or so. Long pointed out that there was no perceptible loss of power with the large-displacement D16, even though the fan drained as much as 70 horsepower. With smaller engines, you can feel a power loss when a fan drive engages, ironically, just when you need power the most while climbing a hill.

With moderate pressure on the pedal, the I-Shift usually upshifted at 1,500 rpm or so, and often skip-shifted as load and terrain allowed. Accelerating from a standstill, the D16 caused the driveline to shudder while the tranny was in lower gears. I wondered if torsional vibrations were coming from the engine, but Long thought the axles were twisting slightly from the torque, sharpening U-joint angles and producing vibes. He later checked and found that because this was a pre-production vehicle, the driveline angles had not been completely “optimized” for the high ride height. Production trucks now are.

While cruise control was engaged, the tranny downshifted nicely but not aggressively on downgrades. But with CC turned off, I had to switch to M-for-manual and repeatedly punch the down button to keep revs up and the engine brake, which was controlled by a stalk on the right side of the steering column, working to the max. This was especially useful on descending off-ramps leading to stop signs. On the level, the engine cruised at 1,300 at 60 mph and 1,420 at 65, according to the gauges.

While P was engaged, the tranny readily downshifted from overdrive—12th to 11th, 10th and lower when needed—but was more reluctant when left in E. Downshifting could be done manually using the down arrow, or by pressing the accelerator almost to the floor, where my foot pushed the pedal past a detent and the tranny kicked down one or two ratios.

I remembered from a previous I-Shift drive to make sure the selector was in D while stopping on upgrades, because then its hill-holding function would engage. This applies the brakes and holds them for 3 seconds until I moved my foot from the brake pedal to the accelerator. If the selector’s in M, hill-holder doesn’t work and the rig can roll backward.

For two-lane work, Long directed me onto State Route 215 and then onto 251, and that got to be interesting. Highway 251 is narrow, and it hugs the banks of the French Broad River; in places there’s absolutely no shoulder between the pavement and steep drop-offs to the water. I was grateful for the VNX’s precise steering, utilizing dual TRW gearboxes, on the 20,000-pound front axle. The parabolic leaf springs over the steer axle were rated at 20,000 pounds and kept the front end steady while never feeling harsh. Highway 251 has many curves, and I had to use a bit of the opposing lane to drag the 48-foot trailer around the sharper ones, but traffic was light so it was no problem.

We missed the turnoff that would’ve taken us directly back to our starting point, so we meandered back toward it via more country roads. For several miles we ran right alongside an old rail line whose skimpy, rusted steel ribbons suggested abandonment; but it led to an active portion with shiny rails and freight cars parked at a large mill of some sort. Beyond that, the rails no doubt reached civilization. So did we, for we were soon trundling along streets in the outskirts of Asheville. Numerous arterial stops and traffic lights made me glad the tractor had an I-Shift.

In fact, I was happy for the opportunity to sample this VNX, which has the brawn for serious hauling but the comfort to do it over long distances.

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CE-Heavy-Duty Trucks Class 7 & 8 >26000 GVW
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