Land Rover will demonstrate the world’s first 9-speed automatic transmission for a passenger car at the 2013 Geneva Motor Show next week.
The ZF 9HP transmission is specifically designed for transverse applications, and is one of the most efficient and technically advanced transmissions ever used in a production vehicle, according to the British brand.
Despite the extra three gear ratios, the 9HP is only 6mm longer and weighs 7.5kg less than the outgoing six-speed transmission, thanks to a number of innovative design features.
Increasing the number of gear ratios from six to nine gives significant improvement in fuel economy and a corresponding reduction in CO2 emissions. Smaller ratio steps give improved response during acceleration and improved shift quality while higher top gear not only reduces fuel consumption but the lower engine revs improve comfort and reduce noise when cruising at high speed.
The lowest ratio in the 9HP is far lower than the existing six-speed transmission and is specifically designed for off-road use, towing and more extreme on-road conditions like gradients and altitude.
Whereas the existing six-speed transmission makes shifts sequentially, the 9HP has a skip-shift function for much swifter downshifting under rapid deceleration or from greater driver input demands. The torque converter incorporates a multi-stage damper system for smoother pulling away and improved refinement.
The innovative adaptive shifting system matches the driver’s mood within seconds, sharpening up during brisk driving then slipping seamlessly into a more economical regime just as quickly when taking a more relaxed approach. Curve Mode, longitudinal acceleration and pedal position all control upshift prevention.
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.