Land Rover has been chosen as lead partner by South Carolina based ZF to build the world’s first 9-speed automatic transmission. Increasing the number of gear ratios from six to nine improves fuel economy significantly, with a corresponding reduction in CO2 emissions. Smaller ratio steps give ‘improved response during acceleration, improved shift quality, drive and refinement’ says Land Rover.
The lowest ratio in the 9HP is much lower than that of the existing six-speed transmission and is specifically designed for off-road use, towing and more extreme on-road conditions like gradients and altitude. Another welcome addition is the ability of the ZF 9HP box to skip-shift when downshifting, something the current six speed was not able to. This will paste a smile on your face when you down shift rapidly.
the ZF 9HP is also a clever auto box, capable of adapting to the mood of the driver. The transmission sharpens up during Need for Speed driving and slips seamlessly into a more economical mode when trundling around town. Fast-Off mode measures the rate of throttle release, anticipates further requests by the driver for high power, then holds the gear if necessary. If the driver requests a downshift when the vehicle is travelling too fast, the transmission will remember the request and make the shift when the speed drops to an appropriate level.
The new 9HP is also a masterclass in packaging. New hydraulic vane-type pump, patented dog clutches replacing bulkier conventional clutch packs, and an intelligently nested gear set have enabled this gearbox to be 7.5 kg lighter than the outgoing six speed model while growing only by 6mm.