The iconic bulldog hood ornament has stood above the grilles of Mack trucks for decades. This year our annual week of equipment reviews, which takes place on the grounds of the Ag in Motion farm show every July, gave us a chance to follow one of those bulldogs down the road for a couple of days. Our intent was to find out what Mack’s 12-speed mDRIVE automatic-manual transmission — which was introduced about five years ago — is like to drive and how a truck equipped with one might fit into a farm fleet.
Saskatoon’s Redhead Equipment loaned us a new Mack 2018 Pinnacle model, which has a set-forward front axle riding on 24.5-inch rubber. The tandem-drive truck was equipped with a 20-foot Neustar grain box.
Brad Oliver, Redhead’s sales manager, says the mDRIVE is by far the brand’s most popular transmission, and it is the most frequently ordered type by customers spec-ing out farm trucks, because of its operator-friendly nature. The Pinnacle is most often the model of choice for farm trucks as well, because it offers at least six inches more ground clearance than the Anthem model, which has a setback front axle to allow for the improved front-end aerodynamics prized by long-haul highway trucks. The 24.5-inch tires, rather than the more common 22.5, add another 1.5 inches of clearance. So the Pinnacle is well suited for off-road work like hauling through farm fields or working on construction sites.
Underneath the hood, our Pinnacle had a 415 horsepower Mack diesel providing power, which the mDRIVE transmission routed through to the tandem drive axles. The mDRIVE transmission allows for both manual and automatic operation, both of which are controlled through push-button operation. And in automatic mode, the truck’s computer does most of the thinking for a driver. Just push “D” and apply some throttle, making it ideal for inexperienced farm workers who haven’t shifted 13- or 18-speed manual transmissions. Mastering those requires a little practice; the mDRIVE doesn’t require any more effort or skill than using the automatic transmission in a pickup truck.
When selecting “D” in the automatic mode, mDRIVE won’t necessarily start the truck off in first gear. Sensors on the suspension airbags inform the computer if the truck is loaded or not. If it isn’t, the transmission will start the rig off in a higher gear. During our un-laden road test, the mDRIVE usually started us rolling in third. The readout on the dash keeps the driver informed of what gear it’s in.
Shifting won’t necessarily follow single jumps either. Often after a third gear start, the Mack jumped to fifth, then to seventh, skipping gears as it continued heading for 12th. Even with those big ratio jumps, the shifts seemed pretty smooth. And it also allowed for very smooth creeping maneuverers, which is almost impossible to achieve on most older auto-shifts. They can really jerk a truck during attempts at very slow movements. The mDRIVE can also be ordered in 13- or 14-speed versions, which add low-end creeper gears. But those wouldn’t be needed on a typical farm truck.
There is also a feature that seems reminiscent of the “kick down” gear change common on 70’s era muscle cars. Push the throttle past the detent and the Mack gears down and throttles up to accommodate a quick acceleration when needed.
For those times when drivers would like to control gear selection, the mDRIVE easily permits that. Just push the “M” on the dash control panel and the transmission reverts to manual shifting. It’s even possible to do this on the go. The LCD display between the speedometer and tach lets the driver know if there are up or down gear changes available. If a driver tries to change to a gear the truck’s speed can’t accommodate, the computer won’t let it happen, so there’s minimal risk of causing driveline damage.
Overall, we liked the mDRIVE and the Pinnacle too. This truck model has a relatively short hood, although it is flat and doesn’t have the downward slope other models, such as a Freightliner FL Series, have that create a shorter blind spot ahead of the bumper. And Mack will be changing to an upgraded cab interior package on 2019 models compared to what our test truck offered. Nevertheless, following that chrome bulldog down the road was a pretty pleasant experience. And it would be especially nice for those with limited experience behind the wheel of a heavy truck, given the ease of operation of the mDRIVE.