ZF Touts Flexible 8-Speed Transmission

ZF Friedrichshafen AG says its new 8-speed dual-clutch transmission can be adapted for all-wheel-drive and/or hybrid-electric applications.

The company is introducing the 8-speed gearbox in the Porsche Panamera awd sedan and its plug-in hybrid derivative that are currently being launched in Europe. The previous Panamera hybrid used an automatic transmission with a torque converter.

Designed for rear- and awd front-longitudinal applications, the new ZF dual-clutch unit can handle as much as 740 lb-ft of torque, according to the supplier. In awd mode, the front axle is driven by a hang-on clutch with a wet multidisk design operated under continuous slip with pressure varied as needed.

Power loss in non-hybrid rwd applications is reduced by as much as 28%, thanks in part to a high gear ratio spread of 11.17. The 8-speed gearbox also gets a demand-driven lubrication system and an optimized electronic control unit. Other purported benefits include faster shift times and improved efficiency.

The company says the system features a compact gear set design that allows a hybrid module—comprised of a 100-kW electric motor, torsional damper and a separating clutch with actuators—to be integrated into the clutch bell housing without increasing the overall length relative to its 7-speed dual-clutch unit. The module can accelerate a vehicle to speeds as fast as 86 mph solely on electric power.

The transmission control unit and related software were developed specifically for the 8-speed system. ZF says the control unit automatically reduces power consumption when operating in “Eco” mode and turns off the combustion engine at speeds of about 5 mph or less as the vehicle rolls to a stop.

ZF produces the transmission at its plant in Brandenburg, Germany.