Test Drive: Optimized Lightweight VNL
Weight-saving components give this tractor more payload capacity, and it pulls very well.
March 2014, TruckingInfo.com - Test Drives
Weight is a precious commodity to truckers who haul bulk commodities. They need to carry as much payload as possible, so they strive to cut pounds from the vehicle without compromising reliability, durability or performance.
The Bulk-hauling Optimized series also includes shorter VNM tractors that, like VNL versions, come as a daycab and several sleeper types.
To help operators like them, Volvo has made lightweight tractors part of its new Optimized series. There are eight Optimized models, all designed for regional and bulk haulers that are focused on maximizing fuel efficiency and payload. There are four each in the VNM (medium-length hood) and VNL (long hood) series, including daycab and sleeper-cab models whose specifications save as much as 1,200 pounds compared to more typical component specs.
Saving weight also saves fuel, noted Chris Stadler, a product manager who briefed me on Volvo’s approach to both.
To evaluate the new Optimized line, I took a light-blue VNL430 for a drive on the roads near Volvo’s New River Valley plant in Virginia, where it was assembled and later staged for this demonstration.
This tractor had a mid-roof, 42-inch-long sleeper, which offers some stand-up living room for the driver while not towering over the tanker and hopper-bottom trailers it’s likely to pull. It saves several hundred pounds compared to a larger sleeper. A low-roof sleeper would save some pounds, but loses some spaciousness. A daycab would save even more, but many operations require sleepers for rest breaks and overnight stays.
Wide-base tires and wheels save 400 to 500 pounds and 1% to 4% in fuel compared to dual tires and wheels, industry testing has shown.
The tractor also had Volvo’s XE (for exceptional efficiency) package featuring the Volvo I-Shift automated mechanical transmission. The package became available in February with the Volvo D11 diesel. Other specs include a 6x2 tag-tandem on wide-base single tires; steel-and-iron brake drums; and aluminum hubs, wheels, frame crossmembers and air and fuel tanks. A Holland fixed fifth wheel is also aluminum. The tractor didn’t have aerodynamic fairings, which could save fuel at highway speeds but add weight, Stadler noted.
At 2,246 pounds, a D11 weighs about 400 pounds less than the more popular D13, according to John Moore, Volvo’s powertrain marketing manager. The D11’s highest rating is a healthy 405 horsepower and 1,550 pounds-feet of torque. Customers can opt for the more powerful D13, and can pick and choose the items on the Optimized list that best suit their operations.
Taking it for a drive
The tractor, hitched to a Walker 48-foot water tanker, was waiting outside after my briefing from Stadler and Moore. I climbed in and found that the VNL’s instrument and panel and controls were all pretty logical and easy to read and use. (Later I found that the HVAC system had difficulty keeping the side windows defogged and maintaining a comfortable temperature at our feet. Maybe it needed some adjustment.)
On this late January day it was unusually cold (for Virginia), with single-digit temperatures that caused a glitch: The diesel fuel in the tank was evidently clouding, and the wax crystals were plugging the fuel filter (“check filter,” warned a light on the instrument panel). We tried driving anyway, but under load the engine intermittently bogged down and wouldn’t develop anywhere near full power. So I turned the rig around and headed back to the parking lot. Brandon Borgna, Volvo’s PR manager, volunteered to chase after some fuel treatment, and meanwhile Moore and I spent time in a VHD dump truck (which I’ll write about another time).
A D11 diesel (this one rated at 405 horsepower and 1,550 pounds-feet) is newly available with the XE package. It’s strong but weighs about 400 pounds less than a D13.
Later we returned to the VNL and the fuel situation seemed fixed. The wave action of the water in the unbaffled tanker had me a bit baffled, because the sloshing’s vibes felt a lot like the engine’s shuddering when it was being choked off. But the filter warning light was out and full power was there, so we headed for the highway.
Moore pointed out that this I-Shift had the “gentle shift” option designed just for these kinds of slosh-prone loads. At first, I couldn’t discern much difference between this tranny and the one in the dump truck, which was very smooth. But after he mentioned it, I then observed that the tractor’s tranny seemed to shift more slowly, which is part of gentle shift. Drivers with more experience in tankers might feel the improvement more.
A mid-roof sleeper extends into the cab, providing stand-up room for people up to 6 feet tall. The I-Shift selector is conveniently mounted on the driver’s seat.
Our gross weight was under 72,000 pounds, plus maybe 400 pounds for the two of us. We weren’t hauling all we legally could, but it was enough to test the powertrain. The engine had plenty of oomph at low speeds, and the I-Shift made the most of what was sent to it.
The “I” in the transmission’s name means intelligent, and it is, picking the right ratio for each situation and skipping gears that aren’t needed. Usually it started in 3rd or 4th and skipped its way upward, though it used each of the higher gears. The selector is conveniently mounted on the right side of the driver’s seat, with lever positions labeled R-N-D-M. For most forward motion, D (for drive) did it all.
I used the M (for manual) setting and a thumb switch on the lever to downshift and get some engine braking as we drifted on a slight downgrade leading to a red traffic light. There the pavement was on a slight upgrade.
When it came time to move, I released the brakes and touched the accelerator, but we rolled backwards.
I learned that I should have put it back into D as soon as I was finished with what I wanted to do in manual. If I had been in D at that light, the Hill Start Assist feature would’ve kept the brakes on for three seconds after I released the brake pedal, keeping us from rolling backwards. In a block or so we took the on-ramp to Interstate 81 south, where we built up to highway speeds.
Testing the D11
With 405 horses the D11 certainly wasn’t underpowered, but so many engines I drive for these articles, like Volvo’s own D13, now make up to 500, and I could feel the difference. However, Stadler and Moore both said these specs aren’t really not meant for full gross weight all the time. They are designed more for runs that are out loaded and back empty, or a diminishing-load run.
The D11 was fine on the level but had to work on upgrades, where the speedo needle fell to 45 once or twice but usually stayed well above that. The speed limit was 70 mph, but I set the cruise control at 65, where in direct-drive 12th gear (and a 2.50 axle ratio) the engine cruised at a leisurely 1,150 or so rpm. This is part of the XE package’s “downspeeding,” which slows the engine by 200 rpm at highway cruising speed and saves about 3% in fuel, my hosts said, because there’s less friction inside the engine. Torque peak is at 1,050 rpm, so at cruise every pound-foot is available to keep a rig rolling.
But performance on upgrades requires horsepower that’s made at higher revs. A detent on the accelerator facilitates downshifting and a rise in rpm; all the horses begin pulling at about 1,500 and faster road speed is restored.
If the time’s available, a frugal driver might want to let the torque at low rpms do the work and save some fuel to enhance his status in his company’s bonus program.
No inter-axle driveshaft indicates the Meritor tandem’s rear axle is a non-driving “tag.” Weight can be transferred from it to the forward drive axle for improved traction. Instead of being slider-mounted, Holland aluminum fifth wheel is fixed – a common setup in bulk-hauling where loads are predictable.
With a moderate to light foot, all upshifts came at or below 1,500 and forward progress was entirely satisfactory. Best of all, much of the driving work – gear shifting – was taken care of and all I had to do was guide the rig along streets and down the road.
Although snow had accompanied the polar air earlier in the week, it was pretty much gone by the time of our drive, and all the pavement was completely clear. So we had no opportunity to test the traction capabilities of the Meritor 6x2, which can automatically transfer load-weight to the drive axle.
On this short demonstration run, all main elements of this Volvo’s weight-reduction strategy – the D11 diesel, the 6x2 drivetrain, and the wide-base single tires and wheels – worked very well. And the XE engine’s very low cruising rpms were entirely compatible with the I-Shift’s operation. These components combine to gain thousands of dollars in revenue per year for a tractor’s owner, and save more money in fuel. It sounds like a financially pleasing plan to me.