Overdrive Magazine | Trucking Business News & Owner Operator Info
Issue link: https://read.dmtmag.com/i/85423
Allison turned truck journalists loose on their Indianapolis test track to pit their new TC 10 in head-to-head competition with current automated transmissions. Although the automated transmissions performed quite well, the new Allison had a clear advantage in con- sistent acceleration and snappy shifts. Drivetrain revolution Innovative approaches to drivetrain design promise more effi cient highway cruising. BY JOHN BAXTER V olvo recently shook up the standard view of how a drivetrain should behave. The truck maker introduced the XE13 option, a system combining a Volvo I-shift automated 12-speed overdrive transmission with axle ratios in the range of 2.64-2.69:1. This gives a 65-mph cruise rpm of 1,150 rpm, a little more than 200 rpm lower than most trucks built today, even when they have conservative gearing. Volvo calls the concept "engine downspeeding." It's among new developments from drivetrain manufacturers aimed at using less fuel to maintain desired highway speeds. The XE13, equipped with a 425- hp engine producing 1,750 lb.-ft. of torque, incorporates "modified software." What this means is the XE13 drivetrain produces good performance by downshifting at a higher road speed when climbing a grade, says Ed Saxman, marketing manager for Volvo Drivetrain. It downshifts at a speed that is adapted to fast gearing – typically, he says, at about 58 mph when geared for the most fuel-efficient 65 mph cruise. 34 OVERDRIVE MARCH 2012