Just when you thought an eight-speed transmission was pretty mind-blowing, along comes a nine-speed. Why the sudden proliferation in ratios? Increasing fuel economy standards, and a desire by auto manufacturers to deliver that improved economy while still delivering the level of performance customers expect. The latest manufacturer to hop on the nine-speed bandwagon is Land Rover, which is showcasing a Range Rover Evoque at the upcoming Geneva motor show equipped with a ZF 9HP transmission. The transmission is made specifically for transverse drivetrain applications such as the Evoque and LR2, two vehicles that are expected to receive the new transmission, possibly as soon as the 2014 model year.
If that code sounds vaguely familiar, it's because it will soon also be offered in the Dodge Dart and the just-revealed 2014 Jeep Cherokee. However, Land Rover claims it was the lead development partner on the 9HP. As such, it made sure the high-tech transmission met its standards for durability, reliability, and smoothness, specifically under towing, off-road, and steep grades.
Among the unique features on the 9HP are a skip-shift feature, allowing the transmission to shift non-sequentially to select a lower gear for full-throttle acceleration, and a memory feature for gear selection, preventing the driver from selecting too low a gear when in manual mode, and software that anticipates driver behavior, measuring the rate of throttle release or pressure, and holding a gear if needed. Part of the software includes a "curve mode" detected acceleration and deceleration modifies shift patterns for optimized performance.
Despite having 50 percent more ratios than its predecessor, the 9HP is only a quarter-inch longer, and is actually 16.5 pounds lighter. This compact, lightweight packaging is made possible by a compact hydraulic vane-type pump, two dog clutches rather than conventional clutch packs, and a nested gearset.
Source: Land Rover