Quattro, the trademark name Audi has put on its all-wheel-drive system engineered for passenger vehicles, recently celebrated its five-millionth installation. The driveline has been offered in more than 140 different vehicles since its introduction more than three decades ago.
The all-wheel-drive technology made its world debut at the 1980 International Geneva Motor Show, beneath the floorpan of the Quattro Coupé, a low-volume two-door. It didn't take consumers long to embrace Audi's innovative approach. While most four-wheel-drive systems at that time utilized heavy transfer cases or second cardan shafts, Quattro was virtually tension-free, light, compact and efficient. Most importantly, enthusiasts found it was especially suitable for sports cars.
Today, the automaker offers Quattro on its full line of passenger vehicles and it is unquestionably successful (the technology enjoyed a 43 percent take rate in 2012). On models with transverse-mounted engines (A3 and TT), Audi uses an electronically controlled multi-plate clutch with hydraulic actuator. Under normal conditions, the clutch sends power almost exclusively to the front wheels (if wheel slippage occurs, up to 100 percent of the torque may be sent to the rear). Vehicles with engines mounted longitudinally (A4, A5, Q5, etc...) use a self-locking center differential sending 40 percent of the engine torque to the front axle and 60 percent to the rear under normal conditions (it is able to send the majority of the power to the axle with better traction when needed). The highest-performing Quattro systems use torque vectoring to further improve cornering grip and speeds.
Articles Source : Autoblog