Land Rover to showcase world's first 9 speed autobox
Land Rover in technical collaboration with transmission technology leader ZF has developed the world’s first nine-speed automatic gearbox. The 9HP ZF automatic transmission has been designed for front transverse applications such as front wheel drive and all-wheel drive cars.
The idea behind developing a nine-speed gearbox was to improve fuel efficiency throughout the powerband of an engine. The ZF 9HP in essence is a torque converter gearbox with a tall ratio for the ninth gear that allows the engine to maintain low revs while cruising, thereby reducing fuel consumption and emissions. More gears also mean smaller step ratios for improved acceleration in the lower gears. The 9HP ZF autobox is also said to have improved shift quality and refinement.
While higher gears in the 9HP autobox have tall ratios the lowest ratio of the gearbox is far lower than that of the existing six-speed gearbox. This will help better low speed response of the engine during off-roading, towing and scaling steep gradients at high altitudes.
ZF states that the new nine-speed gearbox is capable of extremely fast gear changes that are ‘below the threshold of perception’. The gearbox is even capable of skipping gears while downshifting during rapid deceleration with the ‘skip-shift’ function. The gearbox also incorporates a multi-stage damper system for smoother pulling away and improved refinement.