That New Drive – How the PTU Transmission was Born

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Jeep Cherokee

When the new 2014 Jeep Cherokee was designed, Jeep drivetrain engineers knew that Jeep customers expect their vehicles to be capable and come with a true low-range. Not only did they do that, but this FWD-based drivetrain architecture features a true locking rear, a true low-range gear ratio, and the trail performance expected out of a Jeep product. How was the new PTU (Power Transfer Unit) Transmission created? We get a brief from Michael Kirk, Director of Manual Transmission, Drivetrain, and Axle Engineering.

2014 Moab Easter Jeep® Safari - Jeep Cherokee Dakar
The PTU Transmission is a fairly unique idea as not only is this a nine-speed, front-wheel-drive transmission with a rear output, but also it is the only FWD-based SUV with a true low-range and locking rear differential. The powertrain engineers first tried putting a low-range in just the PTU transmission, but it didn’t perform as desired, so they put a low-range on both the PTU and the RDM (Rear Drive Module, the rear axle). This means you will get a true neutral and a true “4-Low” selection since there is a low-range on both axles. Doing this also gave the Cherokee a 52:1 crawl ratio, which is a similar ratio to the Jeep Wrangler. While you won’t get that legendary articulation of the Wrangler, you’ll be able to tackle the same grades.

Check out more in the video where Michael Kirk talks more about the rough draft and winning the Walter P. Chrysler Award thanks to the innovative PTU Transmission.

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