Land Rover will demonstrate the latest in a long line of technical firsts at the 2013 Geneva Motor Show with the announcement of the world’s first 9-speed automatic transmission for a passenger car. 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.
Land Rover is the lead partner on the project, working together with ZF which is widely recognised as the world leader in transmission technology.
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, improved shift quality, drive and refinement. The higher top gear not only reduces fuel consumption but the lower engine revs improve comfort and reduce noise when cruising at high speed.
The 9HP is extremely robust and perfectly complements Land Rover’s rugged all-terrain ability whilst delivering exceptionally high levels of refinement and efficiency. 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, giving the driver a heightened sense of control.
With extremely fast gear changes described by ZF as being; ‘below the threshold of perception’, the 9HP is not only highly responsive but versatile too. Whereas the existing six-speed transmission makes shifts sequentially, the 9HP has a skip-shift function for much swifter down-shifting 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.
“We are extremely excited about the 9HP which has been tailored exactly to dovetail with the unique attributes of our vehicles. It will add another layer of performance, refinement and efficiency, further enhancing Land Rover’s world class abilities,” said John Edwards, Land Rover Global Brand Director.
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 up-shift 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 down-shift 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 9HP is a masterpiece of packaging and despite the extra three gear ratios is only 6mm longer and weighs 7.5kg less than the outgoing six-speed transmission. The small package space is achieved by a number of innovative design features including a new hydraulic vane-type pump, which also contributes to improved efficiency, two patented dog clutches replacing bulkier conventional clutch packs, and an Intelligently Nested gear set.
Land Rover was chosen by ZF, one of the world’s most technically advanced transmission manufacturers, to be the lead partner on the 9HP and Land Rover engineers have worked in partnership with ZF engineers to jointly develop the transmission to suit the brand. The Land Rover transmission engineering team is already extremely experienced in engineering ZF products to suit Land Rover vehicles having integrated the 8HP with the Range Rover, Land Rover Discovery 4 and Range Rover Sport. The 9HP is produced at ZF’s Gray Court facility in South Carolina.