The second generation of the 6-speed automatic transmission from ZF combines seemingly conflicting properties such as driving fun, high performance, and economical driving at the same time. Thanks to the use of a modern torque converter and improved software control and hydraulics, the 6HP features very quick shifting times. It is still one of the most responsive multi-ratio transmissions.
High efficiency and more demanding comfort requirements were the focal points in the development of the second 6HP generation. It was the first transmission for which ZF achieved gear change response times that are partly below the human perception threshold. Direct double shift operations are also possible without interruption. At the same time, the 6-speed transmission boasts high fuel efficiency.
Efficient torque converter
Modern torque converters make it possible to completely close the lock-up clutch immediately after start-up. In order to safely control the vibrations in the driveline in this process, ZF has installed specially developed torsional dampers. At the same time, with the early closing of the lock-up clutch, the connection of the engine to the driveline becomes noticeably more direct and the driver experiences a direct response from the vehicle when actuating the accelerator pedal.
Quick response time
Thanks to its hydraulic system, the 6-speed automatic transmission is able to execute all double shifting operations directly and, in part, to downshift as many as four steps without time loss. The optimal gear is selected by the optimized control electronics: Using data on the load condition, driving situation, and speed at which the pedal is pressed, the software "decides" whether one or more gears are shifted. The response time is always the same: If, at a speed of 70 km/h in sixth gear, a kickdown signal is issued, then the second generation 6-speed automatic transmission needs just 100 milliseconds to actuate the rapid gear change. ZF produces the 6-speed automatic transmission at the Shanghai location for Chinese automotive manufacturers. At present, approximately 300 units per day roll off the production line. By end of 2014 240.000 units had been produced in the China plant.