汽车自动变速外文翻译英文.docVIP

汽车自动变速外文翻译英文 PAGE 2 Vol. 20 NO.3 DRIVE SYSTEM TECHNIQUE September 2006 ZF began developing automated manual trans—missions for commercial vehicles early．The first product was a partially automated transmission with automatic pre—selection，which was introduced into the market in 1 984．Ten years later，an automated transmission followed with the introduction of the first AS Tronic；however，the driver still had to select gears．Its successor model was first e—quipped with an intelligent shift program，which has been in production since 1 998．Thus，a full yautomatic solution was offered in a heavy commercial vehicle for the first time． The chosen transmission concept for AS Tronic resulted in the most efficient solution possible for larger volumes．Extensive integration and remoral of unnecessary components opened up potential cost savings．As a group drive，AS Tronic is designed with an unsynchronized basic transmission and synchronized splitter and range change group，Figure2．In order to reduce the weight of the transmission，a design with two countershafts was chosen，which is optimal in this performance class in termsof weight．Due to a modular design and a basic transmission with 3 or 4 speeds，1 6一speed，1 2一speed，and 1 0一speed variants could be represented．In the basic transmission，the synchronizations were replaced with shift dogs，because the synchronization can take place by controlling the internal combustion engine in modern EDC engines．An additional transmission brake is then required for up—shifts，which is located on one of the two countershafts．A standard dry clutch is used．It is fully automatic SO that a clutch pedal is no longer neeessary．All automated components are pneumatically operated and are combined within modules that are integrated into the transmission housing．The coordinated operation of transmission，clutch，and engine takes place by electronic control，which is located in