DAK is set to transfer box instead of original differential and for power distribution between the front and rear axles. DAK reacts to the difference in points between the axles and automatically locks the "weak". At the same time, the engine power is redistributed to the axle, which has better traction. Due to this, the car is virtually free overcomes any obstacles.
For example, the car rises in steep mountain. Vehicle weight is redistributed to the rear axle, front axle is unloaded. Engine power can not be fully used, since Front axle starts to slip. At this point DAK blocked and gives you the freedom to make a recovery.
The same occurs when heavy acceleration when the car "leans" to the rear axle. DAK makes the front axle at this time "slip" and distributes power to the bridge, which has a better grip.