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The world's first six-speed automatic transmission for passenger cars was introduced to the market by ZF in 2001. The 6HP-family is based on a Lepelletier planetary gear set. An advanced version of these transmissions was launched in 2006. The 2nd generation offers significantly improved customer-relevant features such as reduced fuel consumption, response time and shifting speed. With regard to the increasing requirements especially in reduction of CO2 emissions, a new eight-speed transmission is now under development. The main targets for this transmission family are a further significant reduction in fuel consumption and emissions, good driving performance and state of the art driving comfort. The paper describes the transmission 8HP70, the schematic, main features and major design components. Key figures like transmission weight and size, fuel efficiency benefits and driving performance are shown compared to the 6-speed transmission of the 2nd generation.

With the introduction of the ZF “myTronic6” (6 HP 26) in 2001, the Division Car Driveline Technology of the ZF Friedrichshafen AG has developed and introduced a new 6 speed stepped automatic transmission for passenger cars. This paper describes the gear set concept, the mechanical design and specific functions of this transmission. The 6 HP 26 is part of the new 6- speed program which comprises 3 transmission types. It will replace the existing ZF 5 speed program completely within the next years.

With the introduction of the 5HP24 in early 1996, ZF has completed their product line for 5-speed transmissions. This transmission was especially developed for 8 cylinder engines and has achieved important improvements in fuel consumption, performance, comfort and reliability. This report shows, that 5-speed automatic transmissions result in a reduced fuel consumption, even in countries with speed limits. For example the 5HP24 incorporates the latest developments such as: converter wirth controlled slip clutch (CSC) measures to allow engine speed between 600 and 7200 rpm modern closed loop control shifting strategy performance improved Transmission Control Unit (TCU)