World's first nine-speed auto gearbox
The world's first nine-speed automatic transmission for a passenger car will be unveiled next week.
Land Rover revealed the technology overnight (NZ time) saying that the ZF 9HP transmission - designed for transverse applications - results in significant improvements in real world fuel economy with a change from six to nine gears and a corresponding reduction in CO2 emissions.
Smaller ratio steps are said to 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 lowest ratio in the 9HP is 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.
Land Rover adds that the 9HP, despite three extra 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 experienced in engineering ZF products to suit their vehicles having integrated the 8HP with the Range Rover, Discovery 4 and Range Rover Sport.