4WD Control Module
4WD ECU analyzes the sensor signal of 4WD wheel speed, steering angle, and accelerator. Depends on road and driving condition, it distributes the power to the front and rear wheel by controlling multiplate clutch.
Multiplate wet clutch can deliver the proportional torque to the number of used (active) frictional surface or the axle directional force (pressure) to the clutch. Axle directional force is generated by ball ramp mechanism, which transfer rotary motion to axle directional motion.