Known as the ZF 9HP, the transmission is designed for transverse use as the most efficient and advanced transmission ever in a production vehicle. Land Rover has teamed directly with ZF on the transmission project.
The brand’s current line of vehicles all use a six-speed tranny, and boosting the number of gear ratios to nine will not only produce fewer emissions, but will also improve efficiency.
The smaller increment between ratio steps also enhances response during acceleration with quicker and highly refined shifting. The higher ratio of the top gear saves fuel by lowering engine speed and also reduces noise, thus adding to occupant comfort when cruising at freeway speeds.
The robust nature of the 9HP transmission expands upon the all-terrain prowess expected of a Land Rover while still delivering high levels of refinement and efficiency. The bottom ratio level in the 9HP is far lower than the current six-speed, optimizing the brand’s vehicles for their established forté – off-road use, towing and especially the steep grades found on some highways
The previous incarnation of the Land Rover six-speed would downshift in sequence, but the new 9HP can skip gears to accommodate more rapid deceleration. Should the driver try to downshift when moving too fast for a gear, the transmission will make the shift as soon as engine speed drops to the proper level.
A Fast-Off mode, by measuring the rate of throttle release, learns to anticipate the driver’s automotive performance style, i.e. the demand for additional power, holding a gear as needed to provide the desired torque.
The torque converter uses a multi-stage damper system to smooth acceleration from a standstill while the ingenious adaptive shifting system anticipates the driver's moves within seconds, providing crisp response for brisk driving but easily relaxing into a more economical mode when the driver chills out a bit.
In additional, the Curve Mode detects and analyzes acceleration and deceleration forces, along with pedal position, to control upshift timing.
The masterfully engineered 9HP is only 0.24 inches longer and remarkably weighs 16.5 lbs less than the six-speed transmission, despite the addition of three more gears. This spectacular feat is accomplished via a new compact hydraulic vane-type pump, two patented dog clutches (that replace bulkier standard clutch packs) and a nested gear set.
Land Rover and ZF will continue to collaborate on transmission development providing jointly developed fully integrated transmission solutions in the Range Rover, Land Rover LR4 and Range Rover Sport.
The new nine-speed transmission will be produced at ZF's Gray Court facility in South Carolina.