Planetary Gear Trains: Notes
WARNING: This page is about a different car, the 2015 Jaguar XJ, 2014 Jaguar XJ, and 2013 Jaguar XJ. However, it is still accessible from the selected car via links, so may be relevant.
The 8 forward gears and the reverse gear are produced by a combination of four simple planetary gear sets, 3 clutches and 2 brakes. The front two gear sets share a common sun gear. Power is output always through the planetary carrier of the fourth gearset.
Five shift elements comprising 3 clutches and 2 brakes, are responsible for all 8 forward and reverse gears. High efficiency is achieved by the use of only 2 shift elements disengaged in each gear which reduces drag and so increases the efficiency.