The advantages of Electronic Limited-Slip Differential lock, Haldex, Visco and planetary drive are summarized here. Let's start with the latter. The torque, coming from the transmission affects
to the planetary gearing. Six planetary wheels with a small diameter distribute it as well to the ring gear to the rear axle as to the sun gear to the front axle.
The different diameters of sun and ring gear effect an asymmetrical distribution of torque between front and rear axle, 40 to 60 or 38 to 62, depending on the version.
The three gears of the planetary gearing do have a certain length, because of the relatively high torque to be transmitted. But they have also Haldex helical teeth, giving a direct self-locking effect and
generates forces in the axial direction. This makes the wheels move against side-mounted friction disks for example between the planet carrier and ring gear.
If the front axle loses grip, more torque is directed to the rear axle automatically. As long as this does not slip, sufficient support is available. If the rear axle loses traction, the ESD is needed to intervene because to the
front axle only a limited torque of maximum 600 Nm can be allocated. Without support of at least one axle, the differential lock is not working.
That was '4MOTION'. The 'X' is a special equipment, which includes an offroad reduction in the transfer case and an additional differential lock there, also known as 'longitudinal lock'. By turning a switch on
the center console in level 1 the reduction is made possible by an additional planetary gear, in step 2 and 3 a multi-plate clutch is operated first in the transfer case and then in the rear axle drive. 07/16