Land Rover plans to demonstrate the world’s first nine-speed automatic transmission for a passenger car next week at the 2013 Geneva Motor Show, in a pre-production prototype of its 2014 Range Rover Evoque sport utility vehicle.
Developed by ZF Friedrichshafen AG of Friedrichshafen, Germany, in collaboration with Land Rover, the ZF 9HP transmission will be a standard feature in the production 2014 Evoque, which is slated to debut at dealerships this fall.
Aside from more gears than any other passenger car transmission to-date, it incorporates an array of new, computerized functions that both boost the vehicle’s performance and increase fuel economy.
- Fast–Off Mode measures the rate of throttle release, anticipates further requests by the driver for high power, and holds the gear if necessary.
- Curve Mode detects pedal position, steering angle and lateral acceleration or deceleration forces, and delays upshifts (holds the gear) during aggressive cornering so as not to upset the vehicle’s balance in the turn.
- A skip-shift function hastens downshifting for rapid deceleration by eliminating the need to downshift sequentially. If the driver requests a downshift while the vehicle is traveling too fast for a lower gear, the 9HP remembers the request and executes the downshift when the vehicle has slowed to an appropriate speed.
- An adaptive shifting system adjusts the gear change style to match the driving style — from sharp and aggressive to relaxed and economical — within seconds.
Transmissions with more gear ratios are inherently more economical and efficient than those with fewer, and therefore also reduce emissions. “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,” Land Rover said in a press release announcing the demonstration. “The lowest ratio in the 9HP is lower than [that in] the [current Evoque’s] existing six-speed transmission and is designed for off-road use, towing, and on-road conditions [such as] steep gradients.”
According to Land Rover, the 9HP is “one of the most efficient and technically advanced transmissions ever used in a production vehicle” and is “masterfully packaged.” Despite having three extra gears, it is 16.5 pounds (7.5kg) lighter and only 0.24 inches (6mm) longer than the six-speed transmission it will replace. The compact design was made possible by several innovations, Land Rover said: a nested gear set; two patented “dog clutches” instead of bulkier conventional clutch packs; and a new compact hydraulic vane–type pump.
Land Rover was “the lead partner” in ZF’s development of the 9HP, the automaker said, also noting that the two companies earlier worked together to develop the transmissions used in Land Rover’s LR4, Range Rover and Range Rover Sport models.
The 9HP will be manufactured at ZF’s facility in Gray Court, South Carolina.