Mack Trucks has announced two new versions of its Mack mDrive HD automated manual transmission (AMT). Available in direct or overdrive configurations, the new Mack mDrive HD 13- speed offers a low reduction gear ratio designed for easier starting on steep grades or when the truck is under heavy load, according to the company. The Mack mDrive HD 14-speed, available only in an overdrive configuration, adds a second ultra-low-speed reduction gear designed for curb pouring applications or low-speed, heavy-haul maneuvering. Both transmissions offer up to four reverse gear ratios.
The new Mack mDrive HD models share their architecture with the standard mDrive HD, including reinforced internal components and the same gear ratios for the 12 forward speeds. The addition of the low reduction and multispeed reverse gears is made possible by a short extension added to the front of the transmission case. The new mDrive HD models are less than five inches longer and 90 lbs. heavier than the standard mDrive HD, maintaining a weight advantage of nearly 150 lbs. compared with automatic transmissions, the company said.
For the first time, fleets will also now have the option to spec the mDrive HD in Mack Pinnacle models, including the new mDrive 13- and 14-speed models. The new low reduction gears not only improve performance in off-road, heavy haul and construction applications, they enable as well the use of a faster rear axle ratio to improve on-road fuel economy while maintaining startability.
In addition to the two new models, all Mack mDrive transmissions, including the standard mDrive and mDrive HD, also received numerous updates for improved performance and durability. The transmissions are controlled by a redesigned 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.
Mack also extended warranty coverage on all mDrive transmissions and clutches used in heavy- or severe- duty applications. Warranty coverage now extends to 36 months with unlimited miles for heavy-duty applications for both the mDrive and mDrive HD. For severe-duty applications, warranty coverage is extended to 12 months and unlimited miles for the mDrive, and 24 months, unlimited miles for the mDrive HD. The mDrive updates also included several improvements to power take-off (PTO) controls, including new main cab harnesses for all mDrive models, a reinforced range housing to handle higher PTO bending torque and an all-new cab-mounted Body Builder Module.
