Mack Aims mDrive HD Transmission at Construction Target

By Tom Berg, Truck Editor | May 1, 2015

Construction is among the main applications for Mack Trucks’ new mDrive HD automated manual transmission, the builder’s executives said Thursday in a presentation and driving demonstration in Allentown, Pa.

The mDrive HD will be standard in Granite vocational trucks and tractors, though customers may instead choose manual or Allison automatic transmissions, and optional in the Titan extra heavy duty model, said Stu Russoli, a marketing manager.

“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. The product will go into full production in mid-May, and is available only with Mack MP7, MP8 and MP10 diesels.

Introduced at the World of Concrete show in Las Vegas in February, mDrive HD is based on the on-highway automated transmission announced in 2010. Fuel savings are a primary reason that over half of customers for Mack road tractors now order that version, underscoring the industry wide trend toward automated transmissions in heavy trucks.

Mack officials hope the HD transmission, with stronger gears and synchronizers and higher-viscosity synthetic lube oil, will see similar penetration in vocational trucks. Ease of driving will expand the potential driver pool for vocational fleets, and help attract and retain good drivers, said Curtis Dorwart, Mack’s vocational segment marketing manager.

The 12-speed transmission has automated shifting and clutch operation, and three programmable modes: Enhanced Construction, Heavy Haul and Easy Shift, which are set at production but can be altered, along with other operating parameters, by service technicians at Mack dealers.

About 40 have been installed in Mack trucks and tractors since January. Some have gone to dealers and customers, and some, like the four at the event for press reporters, are on demonstration duty.

The mDrive HD is rated for engines with up to 2,060 lb.-ft., so can handle the 16-liter MP 10’s top output of 2,050 lb.-ft., said Curtis Dorwart, Mack’s vocational segment marketing manager. 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.

An 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.

An mDrive HD will handle most vocational applications, Russoli said, “but there are some where we’ll say, ‘You should stay with an 18-speed manual or stay with an Allison automatic,' and we’ll still offer them all.”

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.

(photos by Tom Berg)