Land Rover to demonstrate the world's first nine-speed automatic transmission
Land Rover will demonstrate the world's first nine-speed automatic transmission for a passenger car at the 2013 Geneva Motor Show. The ZF 9HP transmission is designed for transverse applications, and is one of the most efficient and technically advanced transmissions ever used in a production vehicle. Land Rover is the lead partner with ZF on this project. Increasing the number of gear ratios from six to nine will help reduce emissionsand improve efficiency. Smaller ratio steps also give improved response during acceleration, with improved shift quality and refinement. A higher top gear improves efficiency by lowering engine speed, which also improves comfort and reduces noise when cruising at highway speeds.The 9HP is quite robust and complements the all-terrain capability expected of a Land Rover vehicle while delivering exceptionally high levels of refinement and efficiency. The lowest ratio in the 9HP is lower than the existing six-speed transmission and is designed for off-road use, towing, and on-road conditions like steep gradients.
Whereas the existing six-speed transmission makes downshifts sequentially, the 9HP has a skip-shift function for much swifter downshifting to meet rapid deceleration demands. If the driver requests a downshift when the vehicle is travelling too fast for the selected gear, the transmission will remember the request and make the shift when the speed drops to an appropriate level. "Fast-Off" mode measures the rate of throttle release, anticipates further requests by the driver for high power, then holds the gear if necessary.
The torque converter incorporates a multi-stage damper system for smoother pull away and improved refinement. An innovative adaptive shifting system matches the driver's mood within seconds, sharpening up during brisk driving and then seamlessly shifting to a more economical program when taking a more relaxed driving approach. Additionally, "Curve Mode," detected acceleration/deceleration forces, and pedal position all control upshift timing.
The 9HP is masterfully packaged and despite the extra three gear ratios is only 0.24 inches (6mm) longer and actually weighs 16.5 lbs (7.5kg) less than the outgoing six-speed transmission. The compact packaging is achieved by using a number of innovative design features: A new compact hydraulic vane-type pump, two patented dog clutches replacing bulkier conventional clutch packs, and a nested gear set.
Land Rover and ZF are on-going partners in transmission development; having jointly developed fully integrated transmission solutions in the Range Rover, Land Rover LR4 and Range Rover Sport. The new nine-speed transmission will be produced at ZF's Gray Court facility in South Carolina, USA.
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