Brief description of components: Notes

xDrive consists of the following components:

• Transfer case with multi-plate clutch 

  The electronically controlled multi-plate clutch is housed in the transfer case. The multi-plate clutch distributes the drive torque smoothly and as required  between the front and rear axles.

• VTG actuator motor with incremental sensor and classification resistor 

  The VTG actuator motor (VTG: transfer case) opens and closes the multi-plate clutch. The location of the actuator motor shaft and the adjustment rate are detected by the incremental sensor.

  The classification resistor ensures that mechanical tolerances in the transfer case are considered. Optimum function is thus ensured.

• Actuator lever 

  The actuator lever converts the rotational motion of the VTG actuator motor into an axial motion.

• VTG control unit 

  The VTG control unit regulates the locking torque at the multi-plate clutch in the transfer case in response to the following factors:

  • Demand for required locking torque (comes from the DSC control unit)
  • Condition of the transmission oil (calculated in the VTG control unit)
  • Multi-plate clutch wear (calculated in the VTG control unit)
  • Load on VTG actuator motor (calculated in the VTG control unit)
  • Transmission oil temperature (calculated in the VTG control unit)

  The VTG control unit supplies the following information to the DSC control unit:

  • The locking torque currently set
  • All calculated data

  The locking torque is limited whenever needed in order to reduce the frictional work.

  • > E53, E83
  • > E70
• DSC: Dynamic Stability Control 

  With xDrive, DSC includes the following functions:

  • All-wheel control
  • Automatic Differential Brake (ADB-X)
  • Hill Descent Control (HDC)