Mack Trucks says its mDrive HD 13-speed automated manual transmission with a low-ratio creeper gear will be standard on Mack Granite models starting with production of the 2017 MP-8 engine. The 13-speed boosts productivity with improved performance and reduced weight, said Dennis Slagle, Mack’s president.

Since Mack announced the product in March, customer response has been overwhelmingly positive, encouraging Mack to make the 13-speed AMT standard on the Granite vocational model, he said. The transmission is also available on Pinnacle and Titan models.

“Since its introduction, the mDrive has become incredibly popular – starting first with highway and more recently with many heavy-duty vocational applications,” Slagle said. The introduction of the 13- and 14-speed [versions of the basic 12-speed] expands the range and performance in vocational applications so much so that it is only natural for it to become our standard offering in the Granite model.”

Available with direct or overdrive top gears, the mDrive HD 13-speed offers a low-reduction creeper gear ratio designed for easier startability on steep grades or when the truck is carrying an extra-heavy load, he said. This improved startability also allows customers to select a faster rear axle ratio to decrease engine rpm at highway speeds and save fuel.

All mDrive automated transmissions are monitored by GuardDog Connect, Mack’s proactive diagnostic and repair planning system used by more than 400 Mack dealers.

The mDrive HD has reinforced internal components and the same gear ratios as the basic 12-speed highway version.

Mack also announced in March the availability of the mDrive HD 14-speed, with a second ultra-low-speed reduction gear designed for curb pouring applications or low-speed maneuvering. Both transmissions offer up to four reverse gear overdrive top gear.

The low-reduction creeper and multispeed reverse gears are in a 5-inch extension added to the front of the transmission case. The creeper-gear case adds 90 pounds to the transmission, but it still weighs about 150 pounds less than a torque converter automatic, Mack specialists claim.

All Mack mDrive transmissions have received numerous updates for improved performance and durability, the company said. They include a more precise gearbox control unit, while a new clutch with a larger torsional damper helps reduce driveline vibration. Component wear monitors were also added to enable predictive maintenance.

“Response to the mDrive and mDrive HD has been tremendous,” said Roy Horton, director of product strategy. “Currently, mDrive penetration for Pinnacle axle back and axle forward models is at approximately 80% and 60%, respectively, while mDrive HD penetration for Granite models is about 20% and growing.”