mDrive HD Standard in Granite

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Mack Trucks has unveiled a heavy-duty version of its automated manual transmission. The new mDrive HD will be available as standard equipment on orders as of March in the Mack Granite model, offering improved performance for demanding on- and off-road applications, the company says.

The new transmission is designed and engineered to work exclusively with Mack MP7 and MP8 engines.

The 12-speed mDrive HD has an automated clutch, with operation controlled through a dash-mounted shift pad. For more demanding jobsite maneuvers, shifting can be done manually to hold a gear, downshift, or upshift.

Available in overdrive and direct drive, the transmission continuously monitors changes in grade, vehicle speed, throttle position, acceleration, torque demand, and gross vehicle weight. It automatically chooses the best gear for the road condition, allowing drivers to focus on the terrain rather than shifting gears, increasing safety on worksites.

The normal-duty mDrive was made standard in Mack Pinnacle models last October.

Compared to conventional automatic transmissions, Mack says the mDrive HD requires less service, significantly reducing maintenance needs.

Other features include low weight, said to be up to 237 lb lighter than other transmission offerings. But it has reinforced internal components, with stronger gears and synchros to withstand the more frequent shifting that’s often needed in construction applications.

The mDrive HD uses a transmission-mounted oil cooler, helping to maintain an optimal operating temperature, despite repeated, heat-generating shifts common on a jobsite. 

Unique software packages specific to the application are available. The ‘Enhanced Construction’ package provides optimal on/off-road capability and gives the driver full control over any terrain. ‘EZ Shift’ delivers smoother shifts for sensitive payloads like livestock or bulk liquids.

Interestingly the mDrive HD offers a ‘Rock Free’ feature. Should the vehicle become stuck, it allows the driver to rock the truck back and forth simply by pumping the accelerator.

And then there’s ‘Grade Gripper’. Working with the truck’s ABS system it allows the vehicle to momentarily hold a hill, giving the driver time to move his foot from brake to throttle without rolling backward.

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Rolf Lockwood is editor emeritus of Today's Trucking and a regular contributor to

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