Hill Climbing’s Easy for mDrive and ‘Downsped’ MP8 Diesel
C1 gear easily started this Granite dumper on a 15% upgrade. But so did the mDrive’s normal 1st gear. Photo: Tom Berg
“>
C1 gear easily started this Granite dumper on a 15% upgrade. But so did the mDrive’s normal 1st gear. Photo: Tom Berg
“>
Mack’s mDrive automated manual transmission is a fine piece of work and has gained considerable popularity with buyers of highway trucks since its introduction seven years ago. Now, with low-ratio gears added, it’s even more capable and should become more desirable for people who run vocational trucks.
That was my take-away after demonstrations and driving sessions at the builder’s Customer Center and nearby public highways in Allentown, Pa. Also shown off last week were some of Mack’s 2017 diesels, which are smooth and gutsy, though any performance differences with current engines are not obvious.
The mDrive is Mack’s version of the Volvo I-Shift, but it’s tuned to match the operating characteristics of Mack Power diesels, whose mechanicals are also shared with the sister company. Electronic calibration sets the engines and transmissions apart and carefully deliver what Mack customers want, executives say.
Creeper ratios within a 5-inch-long gear box added to the front of a basic 12-speed mDrive HD convert it to a 13- or 14-speed unit. That gives a truck greater startability, especially on upgrades, and/or the ability to move out with extra heavy loaded rigs, such as with long combination vehicles on turnpikes and elsewhere in the United States and Canada.
Startability was graphically demonstrated with a loaded Granite dump truck on a steep grade near the center’s oval track. Tim Wrinkle, vocational segment marketing manager, acted as instructor as I tried out the vehicle. First we ran around a short circle shot with potholes, humps and rough stone pavement. There was a whole lot of shakin’ goin’ on, and we were both grateful for our air-suspended seats.
The hill was meant to be the real test for the 14-speed mDrive. Wrinkle …Read the rest of this story
