Test Drive

Jack Roberts | May 01, 2011

My foot hovered over the brake pedal, waiting to pounce if our speed started to get away from me, but this transmission held its own. On a few really steep grades, an additional downshift to 10th gear was in order, and the mDrive easily met the challenge.

It was just as effective when climbing. It downshifted as needed with no casting about for the right gear. And once we were on the western edge of the Smokies, the mDrive worked with the cruise control, engine and engine brake to maintain speed without engine over-revs or sudden spikes in fuel use. All told, it’s a slick, intuitive system.


Transmission type: Two-pedal automated manual

Forward gears: 12

Maximum torque input capacity: 1,920 lb.-ft.

Transmission oil change interval: 500,000 miles

Automatic transmission fluid: 15 liters/75w80 synthetic for initial fill and replacement

Clutch: Dry, 17-inch single-plate organic clutch managed via the vehicle, engine and transmission electronic control units.

Direct drive ratios: 12 from 14.94-1.00

Overdrive ratios: 12 from 11.73-.78


The mDrive uses compressed air and electrical solenoids to perform shift functions, clutch control and countershaft brake functions. Its special features include:

AUTO NEUTRAL – Transmission shifts to neutral if the engine is turned off while still in gear or when parking brake is applied.

GRADE GRIPPER – Holds the service brake on grade until the throttle is applied.

GEAR SELECTION ADJUSTMENT – Starting gear and driving gear can be manually selected by using up/down button on premium shift pad.

POWERLEASH ENGINE BRAKE – Automatically downshifts to maximize engine brake performance.

EASY SHIFT – Provides smooth, precise gear shifts for cattle hauling, liquid bulk hauling, or applications where load shifting must be minimized.

Cruise’n Brake – Provides engine brake operation while in cruise mode until target speed has been reached.

LOW SPEED MODULATION CONTROL – Provides smooth low-speed control without the need to continually brake and accelerate.

MACKCELLERATOR – Allows the driver to manually raise the engine RPM while automatically shifting to a lower gear, affording higher RPM and increased horsepower to assist with a quick pass without taking hands off the wheel or eyes off the road.

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