OK I googled it. Its called Quadra drive II and has to have the Vari-lok axles with it.
"A new four-wheel drive system, the Quadra-Trac II, incorporates a progressive, speed-sensing torque transfer differential. The system also marks the first industry use of Vari-Lok axles that have a progressive, speed-sensing torque transfer differential in both the front and rear axle. Without any driver involvement, the Quadra-Drive system keeps the vehicle moving even if only one wheel has minimal traction. Unlike other systems, Quadra-Drive works without straining, wearing or compromising the anti-lock braking system.
Quadra-Drive is standard with the V-8 and an option on the six-cylinder. On vehicles assembled in Austria, Quadra-Drive will be offered with all engines.
Under normal driving conditions, the Quadra-Trac II transfer case transfers most of the power and torque to the rear wheels. The moment a wheel loses traction, a speed variation between the front and rear axle occurs and a gerotor pump applies hydraulic pressure to a multi-disc clutch pack. This bridges the coupling, minimizes speed difference and sends power to the front axle.
The gerotor pump is similar to an engine oil pump. The rotor is driven by the front drive shaft and the case by the rear drive shaft which creates a pressurized oil flow to the clutch pack in proportion to their speed variation. As with the pump, clutch discs are alternately splined to the front and rear drive shafts.
Faster response compared to viscous couplings results from the ability of Quadra-Trac II to immediately pressurize the clutch pack and bridge the coupling when a speed difference occurs. A viscous coupling tends to respond more slowly because it indirectly transfers torque through a viscous fluid and never fully bridges the coupling. Another advantage over viscous couplings is that the gerotor pump uses the same lubricant supply as the rest of the transfer case, not needing the extensive sealing between the viscous fluid and the gear lubricant.
As in all Jeep vehicles, the Quadra-Trac II transfer case includes a low range for off-highway operation. Selecting low range gives a torque multiplication ratio of 2.72 and fully locks the center differential.
The gerotor pump incorporated in a Vari-Lok differential is conceptually the same as that used in the Quadra-Trac II transfer case. Its operation is virtually transparent to the driver.
Power transfer in a Vari-Lok differential is proportional to wheel speed difference rather than torque difference as is typically the case in mechanical limited-slip systems. Because conventional limited-slip differentials are initially pre-loaded to assure torque transfer, normal use tends to cause wear that reduces the ability of the differential to transfer torque over time. By design, the Vari-Lok differential is virtually wear free.
Compared to systems with a viscous coupling, which also sense speed, Vari-Lok differentials respond more quickly and smoothly to wheel slip. Response of the gerotor pump can be precisely tuned to driving conditions, enabling the use of this advanced system in the front axle as well as the rear."
Topic: ZJ Quadra = locker? (Read 2350 times)