The new twin-clutch transmission is designed to work with longitudinally installed engines and the quattro all-wheel drive system, and its 550 Nm torque capacity makes it suitable for a wide range of sporty models. Audi will introduce the new S tronic into multiple model lines in series production during the course of this year.
With the seven-speed S tronic, Audi is launching a new phase in its drive strategy. The new transmission, which was developed entirely by Audi, is intended for the mid-range model lines. Audi has designed it to be sporty while also being a highly efficient high-tech component.
Audi drivers can use the new seven-speed S tronic in various modes. The fully automatic mode, in which the computer selects the gear, keeps the D (Drive) and S (Sport) programs available. The gears can also be manually switched with the shift selector lever or with the optional rocker switch on the steering wheel – an amazingly fast process.
The new high-tech transmission from Audi gives the driver a dynamic and comfortable sense of shifting with unsurpassed precision and perfection. It combines outstanding economy with superb agility and potential for sporty driving.
The seven-speed S tronic is composed of two transmission structures. It integrates two multidisk clutches that control different gears. The large K1 clutch located on the outside conducts the torque via a solid shaft to the gear wheels for the odd gears 1, 3, 5 and 7. They are located in the rear of the cast-aluminum transmission housing, toward the center of the vehicle.
A hollow shaft rotates around the solid shaft. It is connected to the smaller K2 clutch, which is integrated into the inside of its larger sibling, and which controls the gear wheels for the even gears 2, 4 and 6, as well as reverse gear. All gear wheels are located in a single row on both drive shafts, in the order 4, 6, 2, R, 1, 3, 7 and 5.
Both transmission structures are continuously active, but only one is powered at a time by the engine. For example, when the driver accelerates in third gear, the fourth gear is already engaged in the second transmission structure – lying in wait, so to speak. The switching process takes place as the clutch shifts – while K1 is opening, K2 closes at lightning speed. This process takes only a few hundredths of a second and is completed without interrupting traction. It is so comfortable and smooth that the driver hardly notices it.
The power flows from the drive shaft to the self-locking center differential of the quattro drivetrain, which distributes it into two directions. In the basic distribution, 60 percent of the torque flows over the cardan shaft to the differential for the rear axle, and 40 percent flows over a side shaft to the bevel gear of the front-axle differential. Because this shaft is installed at a 7.2 degree angle, it uses a slanted, beveloid gear. To reduce weight, it is also hollow.
The asymmetric-dynamic power distribution provides sporty and agile driving characteristics with slight emphasis on the rear end. When needed, the center differential can deliver up to 85 percent of the power to the rear axle or a maximum of 65 percent of the power to the front axle. |
