Equipment Type

Volvo I Shift Tackles The Rough Stuff

Volvo’s AMT has capabilities for getting out of off-road holes, but the driver needs to know about them

February 17, 2014

When it came on the North American market about seven years ago, Volvo’s I-Shift was approved for on-road use but not for on/off-road trucks, except by special OK from engineers at Volvo Trucks’ headquarters in Greensboro, N.C.

Since then, the I-Shift has been officially approved for the burly conventional-cab VHD, for Volvo Heavy Duty. Engineers have added a slew of special features that give drivers more control over what the transmission, and the truck it’s in, does. Volvo managers invited me to drive a VHD dumper where the truck was assembled, at the New River Valley plant at Dublin, Va.

In a large area behind the plant, workers are carving on- and off-road courses where their highway trucks can be demonstrated and tested by potential and actual customers. As you might guess, they’re using Volvo construction machines; but they’ve been idled by wet fall and winter weather, some of which hit a couple of days ahead of my visit toward the end of January. Several inches of snow had fallen—an unusual happening in Virginia—and polar air had descended. Although uncomfortable even for northerners like me, the frigid air was fortunate because it froze the ground and allowed us to venture onto the uncompleted course and motor over its trails instead of sinking into mud.

Test Set

  • Truck: Volvo Heavy Duty (VHD 64B-200) 6x4 conventional daycab, BBC 113.6 inches
  • Engine: Volvo D13, 12.8 liters (782 cubic inches), 500 hp @ 1,400-1,900 rpm (governed speed, 2,100 rpm); 1,750 lb.-ft. @ 1,050-1,500 rpm
  • Transmission: Volvo I-Shift ATO2612D, automated mechanical 12-speed overdrive w/ automated clutch
  • Front axle: 20,800-lb. Volvo VF20, on taperleafs
  • Rear axles: 46,000-lb. Meritor RT46-160 w/ 3.58 ratio, with locking diffs, on Volvo T-Ride mechanical suspension
  • Wheelbase: 200 in.
  • Brakes: Bendix S-cam w/ Bendix ABS
  • Body: Rhodes 18-foot polished aluminum dump bed

“Us” included John Moore, Volvo’s power train marketing manager, who was my guide on our jaunt over the frozen earth (he casually referred to it as “frozen tundra,” but Packer fans like me know that such sacred ground exists only in Green Bay, where it was even colder on this day). He piloted the VHD around what is for now a totally off-road course, because a loop for highway trucks is only partially graded and not yet paved. That’ll happen in spring and summer, which from this day, with Fahrenheit temps in the teens, seemed many months off. On rough sections, I held on tightly because although my passenger seat was wide—possible in the Volvo’s commodious cab—it was solidly bolted to the floor, so I could feel every bump. Later I moved to the air-ride driver’s seat and Moore bounced around.

Moore’s a mechanical engineer by trade, which helps in understanding what goes on inside an I-Shift and its electric controls, but here he concentrated on explaining some features available in the product’s Performance Plus option, which comes with a Premium selector. That includes an up (+) and down (–) thumb switch and a push button labeled E/P+. P means Performance; choosing it raises shift points so the engine revs faster to develop more horsepower. E means Economy, wherein the tranny upshifts sooner to save fuel. The Basic shifter has neither of those special switches but still includes the M function, which a driver can use to hold the gear he’s in.

Althrough the I-Shift can simply be placed in D and driven through all sorts of terrain, knowledge of how to use Performance Plus’s additional capabilities gives a driver some “outs” in tough situations. Two features, Rock Free and Power Launch, mimic what’s done by good drivers with manual transmissions. I-Shift just makes it easier, Moore said. He first demonstrated them, then let me try them from behind the wheel.

Rocking is done when the truck becomes stuck in mud and loose soil (or snow, if you’re lucky enough to be in it). You choose a lower gear, release the clutch and apply power to move forward, then declutch and let the truck roll back to where it was, then quickly repeat the powering and depowering. Gradually, you lengthen the tire furrows and make a pathway to escape. You can also rock in reverse gear.

With I-Shift’s Rock Free, you first punch the E/P+ button for the performance mode, then move the lever to M. Then goose the throttle to move ahead, let off the throttle to allow the truck to roll back, then repeat as needed. The clutch engages and disengages as the powering starts and stops. When the truck breaks free, you keep going. You can either leave it in M and upshift by thumbing the up (+) end of the switch, or shift to D and the transmission will automatically upshift as conditions allow. This feature will also work in R, where you’d use the accelerator and maybe touch the brake pedal; once free, you’ll stay in the one reverse gear until you’re clear of the trap.

Power Launch is done under similar conditions. With a manual tranny, you rev up the engine and quickly release (but don’t “pop”) the clutch pedal; power suddenly goes to the rear wheels, launching the truck out of the hole—you hope. With I-Shift, select P+ mode and shift to M; thumb down (-), get on the go-pedal—the electronics won’t let the engine rev past a safe 1,300 rpm—and quickly release the thumb switch. The clutch engages and the truck moves out; if not, do it again. If you need to power-back out of a hole, select P+, shift to R, hold the down (-) button, rev the engine, and release the (-) button to launch in reverse. I-Shift’s smoothness reduces the beating the driveline takes.

Neither time were we actually stuck, so Moore’s demonstration and my practicing were simulated. I can imagine these techniques would help if a truck were bogged down, and knowing how to perform them would give a driver an edge. If not, the guy or gal might play with the selector and the throttle and try for similar results. Drivers need some instruction before operating any auto-clutching automated transmission in rough conditions, or on pavement for that matter. Otherwise, it’s possible to abuse the clutch, though not near as badly as with a manual tranny.

Moore also showed me a third feature with a Performance Plus I-Shift, which is called Greatest Possible Downshift. You press and hold the down (-) button and change the gear selector from D to M. Then release the (-) switch. I-shift will make one large downshift instead of several smaller ones—useful when approaching a steep hill in off-road conditions when a higher engine speed is needed. I-Shift uses its grade sensor and vehicle mass calculations to determine the best gear to select. Press the up (+) end of the thumb switch, and the transmission will upshift whenever it can. That’s neat, except I prefer lower revs and might avoid this capability.

When we were done with the off-road course, we headed for the highway. Moore directed me onto nearby Interstate 81, and we headed south before doubling back via a winding frontage road and northbound I-81. The VHD was very nice to drive—quiet, good ride, excellent visibility—with plenty of power to move our gross weight of 63,480 pounds (18,639 of chassis, 615 of fuel, 3,126 for the Rhodes dump body, and 30,000 pounds of stone). In overdrive/12th gear, it cruised at 65 mph with the engine spinning at about 1,500 rpm, which is right for a vocational rating where higher revs are desirable (highway versions cruise at 1,150 to 1,350 rpm).

Even on the highway, the Premium selector’s thumb switch is valuable for commanding downshifts while exiting onto off-ramps and while going down hills, especially if the engine has a retarder. The Basic selector doesn’t have this, and even though I-Shift will automatically downshift as road speed slows, it doesn’t do so aggressively. So a driver has to use the service brakes more. The Basic selector also doesn’t have the E/P+ switch, but retains a kick-down feature that will downshift the tranny if the driver wants more power. There’s a detent in the accelerator that the driver can feel, and he’ll also feel whatever performance boost is on tap.

About seven out of 10 Volvos now have I-Shifts as they go out the doors of the New River Valley plant. It’s standard on all models now, and although a buyer can delete it in favor of an Eaton manual of some sort, the discounts aren’t huge. Choosing an LL-type manual gearbox on a VHD saves a couple of thousand dollars—not enough, in my opinion, to pass up this smooth auto-tranny. Volvo also offers Eaton’s AutoShift and UltraShift AMTs, so there’s no good reason to shift for yourself unless you really want to.

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