przez GaRaż » wtorek, 9 stycznia 2007, 16:10
ATTESA-ETS (acronym for Advanced Total Traction Engineering System for All - Electronic Torque Split) is the advanced electronic version of Nissan's ATTESA four-wheel drive system. The newer version of ATTESA E-TS is called ATTESA E-TS Pro.
ATTESA E-TS is featured in the north-south layout vehicles, such as the Nissan Skyline GT-R, utilises what is mostly a conventional RWD gearbox. Although the Skyline GT-R is exclusively AWD, ATTESA E-TS is also used in Nissan models that are also available as RWD such as the A31 Nissan Cefiro. Drive to the rear wheels is constant via a tailshaft and rear differential, however drive to the front wheels is more complex by utilising a transfer case at the rear of the gearbox. The drive for the front wheels comes from a gear which hangs off the right side of the transfercase. The front driveshaft runs along the right side of the transmission, to a differential located to the right of the engine's oilpan. The front right axle is shorter than the left, as the differential is closer to the right wheel. The front left axle runs through the engine's oilpan to the left wheel.
The ATTESA E-TS layout is more advanced than the ATTESA system, and uses a 16bit microprocessor that monitors the cars movements at 100 times per second to sense traction loss. Three G-Sensors mounted underneath the centre console feed lateral and longtitudinal inputs into an ECU. The ECU can then direct up to and including 50% of the power to the front wheels. When slip is detected on a wheel, the system directs the torque away from that wheel to one that has traction. Torque is apportioned using a clutch pack center differential, similar to the type employed in the Steyr-Daimler-Puch system in the Porsche 959. This series of clutch packs is contained within the 'transfer case,' which is mounted to the rear of the gearbox.
Rather than locking the AWD in all the time or having a system that is "all or nothing", the ATTESA E-TS system can apportion different ratios of torque to different wheels as it sees fit. This provides the driver with an AWD vehicle that performs like a rear wheel drive vehicle in perfect conditions and can recover control when conditions aren't as perfect. The advantage to a more traditional ATTESA (Viscous LSD) system is response in hundredths of a second.
Attesa-ETS Pro
In 1995, with the introduction of the R33 Skyline GT-R, Nissan introduced a new version of their Attesa system. It was named Attesa-ETS Pro, as an upgrade from the earlier Attesa ETS. It was standard equipment in the R33 Skyline GT-R Vspec model, however it was offered as an option on the standard R33 Skyline GT-R, and called the "Active LSD option". It was also standard equipment on all R34 Skyline GT-R models.
Attesa E-TS Pro differs from the standard Attesa E-TS in a few ways. Where Attesa E-TS controls the front to rear torque-split, the Pro is also capable of left-and-right torque split for the rear wheels. This is done via an active rear limited-slip differential. Additionally, the Attesa E-TS Pro was marketed as controlling the four-wheel independent ABS braking system. This is not part of the AWD system, but the ECU makes use of the same sensors to determine wheel slip, and traction.
On Attesa E-TS Pro equipped vehicles, the front differential remains a standard limited slip differential, not being linked to the Atessa E-TS Pro system.
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