, Land Line senior technical editor | Tuesday, September 09, 2014
MARSHALL, Mich. – Eaton introduced a line of transmissions Sept. 4 that offer dramatic improvements for trucking operations, including pickup and delivery and expediter applications.
Called Procision, the first dual-clutch transmission for Class 6 and 7 vehicles offers improved fuel economy, greater reliability, easier operations and improved safety features compared with current standard, automated manual transmissions (AMT) and torque converter automatic transmissions.
The two-pedal (accelerator and brake) 7-speed transmission can handle torque inputs to 660 lb-ft. In multiple tests in otherwise identically spec’d trucks weighing about 26,000 pounds and powered by Cummins ISB 6.7 liter engines, the Procision consistently beat comparable Allison-equipped fuel economy by 8 to 10 percent. Tests followed SAE protocols.
The Procision’s design life (miles that 90 percent of the transmissions exceed) is 400,000 miles, with service intervals for fluid and filter changes at 150,000 miles. The 25 pints of synthetic fluid lubricate, cool and assist the two sets of wet clutches’ operations. They carry a three-year warranty with no mileage limit.
The dual clutch design allows preselection of gears. When shifts are called for by the electronic control module, one clutch disengages as the one coupled to the next gear engages, resulting in virtually no break in torque application the way you get with manual transmissions or current AMTs. Shifts, both up and down, are quieter and far smoother; almost car-like.
Fifth gear is direct, and the top two are overdrive. The overall ratio is 10.13 to 1, with a 6.15 reverse ratio. Controls are similar to an AMT, with a manual selection mode and a low mode that allows downshifting only.
Multiple safety and convenience features are based on the control module’s ability to determine weight, grade angle and throttle positions (driver demand). When parked on a grade as great as 8 percent, shifting into gear activates Hill Helper to prevent the truck from rolling for up to 4 seconds. Both forward and reverse creep speeds are adjustable by authorized Roadranger personnel.
I was among the trucking press last week at the proving grounds. I drove up and down a number of specially constructed grades ranging from 3 to 20 percent, in both a Procision-equipped truck and one with an Allison. The Procision had no trouble climbing the 8 percent grade at a steady 5 mph with no throttle input. Going up 15 percent did require a two-pedal launch. Reverse creep is slower than forward, at 1.5 mph and 2.5 mph, respectively, on level ground.
When the new 7-speed transmissions are available on the North American market in mid-2015, expediter trucks will be among the first targeted markets.
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