Overdrive Magazine | Trucking Business News & Owner Operator Info
Issue link: http://read.dmtmag.com/i/85437
TEST DRIVE (Continued from Page 34) The mDrive doesn't just respond to the engine – it drives it. Gears are selected according to road conditions. The transmission has an inclinometer so that it knows if the truck is going up- or downhill. It knows what the driver wants through the throttle position and tells the engine what is needed. Starting out, it gradually closes the clutch for an impeccable response to the first squeeze of the throttle pedal. When it's time to shift gears, the transmission commands the engine to back off and break the torque flow. The transmission then float-shifts to the next gear, exactly matching engine revs to smoothly swap gears. In an upshift, the transmission PARTNERS IN BUSINESS The 2011-2012 Manual An in-depth, comprehensive source of information for running an owner-operator business, produced by the editors of Overdrive and the owner- operator business services provider, ATBS. only $1995 Order your copy at: www.pibmanual.com Visit www.piblive.com for more information about the Partners in Business program and upcoming seminars. 60 OVERDRIVE JUNE 2012 may call on the engine brake to slow the rpms, snapping shifts faster than even the best driver could. At Mack's Customer Care Center test track, when I accelerated up a 10 percent test hill from a standstill, the Mack just picked up gears as it accelerated away, block shifting one to three, then four and five to make the most of the transmission's capabilities. Such an extreme start was never necessary on the highway, but the transmission would often skip gears, either to make the most of the acceleration or to bring in the Powerleash engine brake for maximum retarding. At the same time, it worked toward optimum fuel economy. Negotiating Kentucky hills at start, the numbers on the dash display climbed to a very creditable 7.3 mpg. Then as we got into the serious climbs of West Virginia into Allentown, fuel economy crept back to 6.9 mpg -- not at all bad given the heavy load and the mountains. What's really nice is the way the mDrive handles the unexpected, like a car suddenly slowing in front of the truck or an obstacle in a corner. You can focus on dealing with the situation, confident that when you walk on the throttle again, you're going to be in the right gear. We started out mid-morning and took a break after four hours. When I pulled up at the Customer Care Center, gates I felt fresher and more alert than I had at the lunchtime stop. That says a lot for the Mack, and speaks well of the transmission. automotive and r cover Contributing Editor St eve St ed trucking, urgess has elated fields for more than 30 years.