Land Rover unveils first nine-speed automatic gearbox

The ZF 9HP gearbox is designed for transverse applications, and is said to be one of the most efficient and technically advanced transmissions ever used in a production vehicle. Land Rover says that increasing the number of gear ratios from six to nine brings significant improvements in fuel economy and a corresponding reduction in CO₂ emissions. Whereas the existing six-speed transmission makes downshifts sequentially, the 9HP has a skip-shift function to meet deceleration demands. If the driver requests a downshift when the vehicle is travelling too fast for the selected gear, the transmission remembers the request and makes the shift when the speed drops to an appropriate level. A '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, while an adaptive shifting system moves to a more economical programme when the vehicle is slowing down. The 9HP weighs in at 7.5kg less than the six-speed gearbox. Additional features include a new compact hydraulic vane-type pump, two patented dog clutches which replace bulkier conventional clutch packs, and a nested gear set.