The mDrive HD will be standard in Granite vocational trucks and tractors and available in the Titan extra heavy duty model. About 40 vehicles have been built with it on a limited production basis since January. All Macks are built in Macungie, Pa., and mDrives are assembled at Volvo Group’s drivetrain plant in Hagerstown, Md. Workers at that plant also build I-Shift vocational and highway automated transmissions for Volvo Trucks, Mack’s sister company.
Mack has a long heritage in vocational trucks, and the heavier duty mDrive was extensively tested before entering that product line, said Stu Russoli, the former vocational manager who just moved into marketing highway vehicles.
“We didn’t want to put it in construction applications until we knew it would stand up to frequent shifts and heat seen in off-road running,” he said. Aside from strengthened interior parts and the thicker oil, mDrive HD’s oil cooler was mounted to one side of the casing so it’s closer to the heat exchanger up at the radiator.
The three available operating modes are a function of programming mDrive’s electronic controls. They can be altered and parameters reset at Mack dealers. An available Performance button on a dash-mounted selector raises shift points and adds power and torque as engine revs rise, making a truck noticeably livelier during acceleration.
A 12-speed mDrive HD weighs 237 pounds less and costs “significantly less” than a similarly torque-rated Allison fully automatic torque-converter transmission, heretofore the only self-shifting alternative to a multi-speed manual in Mack vocational models, Dorwart said. A single-countershaft mDrive weighs about the same as a comparable Eaton manual transmission with twin countershafts and less than a triple-countershaft Mack manual. He and Russoli declined to cite price details.