The seven-speed sports automatic transmission
The seven-speed sport automatic from BMW allows extremely rapid gear changes in automatic as well as manual mode with no disruption of tractive force. This provides for exceptionally sporty as well as harmonious acceleration.
The background is the use of an innovative double-clutch transmission (DCT). This technology, which has its roots in motor sport, involves two separate drivetrains each with its own clutch. One for the even gears and one for the odd ones. For instance, when changing from the second to the third gear, the third gear in the inactive drivetrain is engaged. Then the clutch for this drivetrain is closed while the clutch for the active drivetrain (in second gear) is simultaneously opened. The
The DCT is implemented as a twin-shaft pair of wheels, in which all the cog wheels are in a row. The gear change is hydraulic. A combination of dry sump and injection lubrication is used in order to further optimise efficiency.
The sporty tight gradation of the seven gears provides the optimal gear ratio in every driving situation. And the seven-gear sport automatic can be driven in automatic or manual mode. Manual gear changes are either made using the gear stick of the shift paddles on the steering wheel.
The double-clutch transmission is available as M DCT Drivelogic for some BMW M models. This includes eleven specially-configured driving programmes for even sportier acceleration.