Taking the Volvo VNX Heavy-Haul Tractor Out for a Spin
Combine the frame from the vocational VHD with the comfort of the VN highway tractor and you have something strong for long hauls.
June 2014, TruckingInfo.com - Test Drives
How heavy is heavy haul? For Volvo Trucks’ VNX, it’s as much as 200,000 pounds gross combination weight. The one you see here is spec’ed to haul up to 125,000 pounds. As driven, however, with an East BST flatbed carrying palletized concrete blocks, this VNX was a much more normal 77,780 pounds gross combination weight with a full fuel tank.
My hosts had planned for a lowboy loaded with a piece of Volvo earth-moving machinery, but had trouble obtaining an overweight permit. However, normalcy worked as well as anything to highlight the VNX’s attributes — plenty of power, steady steering, a smooth ride, and a driver-spoiling interior — 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.
We’ve wanted to get our hands on a VNX to drive since they were introduced at the 2013 Mid-America Trucking Show. Units weren’t readily available after they began being assembled last fall at the New River Valley plant in Virginia. The first ones went to dealers in January and this one came up a few months later. It was impressive just to look at, and the Volvo I-Shift automated manual transmission made the tractor and trailer almost as easy as driving a long limousine. So I could just steer, brake, and turn the wheel, and observe how the vehicle handled on freeways and fairly narrow state highways.
Wade Long, director for product marketing, explained that 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 24.5-inch 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 also available.
While the VHD’s largest engine is the 12.8-liter D13 and the VNL can be had with the 14.9-liter Cummins ISX15, the VNX comes with just one engine, the 16.1-liter D16. Like other Volvo-branded diesels, it’s made by what used to be called Volvo Powertrain, which also builds Mack variants, in Hagerstown, Md. This one was rated at 600 horsepower and 2,050 pounds-feet, and we never lacked for go-ability.
Why no Cummins option? “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.
Anticipating flatbed and lowboy loads, the test tractor had an aluminum headache rack with steel supports. Access to the rear deck and air and electrical lines was very good.
Taking the Wheel
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, and the Swedish-inspired diesel felt stronger than a Scandinavian longship full of hard-rowing Vikings.
On upgrades of 6% and more, road speed dropped to 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 190 degrees; 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 – 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. Long later checked and found that because this was a pre-production vehicle, the driveline angles had not been completely optimized for the 4-inch-higher ride height — something that was adjusted on the production models.
While cruise control was engaged, the automated transmission downshifted nicely but not aggressively on downgrades. But with cruise 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 punched, the transmission 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 a detent is passed and the tranny kicks 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 the driver can move his foot from the brake pedal to the accelerator, and the rig won’t slip backwards.
For two-lane work, Long directed me onto the scenic byways of State Route 215 and 251, and that got to be fun. Highway 251 is on the narrow side of road engineering, and it hugs the banks of the French Broad River. In places there is no shoulder between the pavement and steep drop-offs to the water. I was grateful for the VNX’s precise steering, using dual TRW gearboxes, on the 20,000-pound front axle.
The taperleaf front suspension was soft enough at a 16,000-pound rating for a smooth ride, yet never yielded enough to where the tractor felt unsupported. 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 have 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 hefty but comfortable VNX, which has the brawn for serious hauling but the comfort to do it over long distances. What will it haul? Anything extra heavy and perhaps oversized, like machinery, double trailers of construction supplies, timber — you name it. How many VNXs Volvo will sell, and how well it will compete against rival heavy-haul tractors, including the Titan from sister company Mack, is something for the economy and the market to decide.