The Hyperlogos

The transfer case is the part of a four wheel drive vehicle which distributes power between the front and rear axles. All wheel drive vehicles have a differential instead. The transfer case differs primarily in that the front and rear wheels are driven at the same speed. Typically, the transfer case also allows the disengagement of the drive shaft leading to the front axle, and it usually also has a neutral mode which allows disconnecting both axles for the purpose of towing the vehicle.

The transfer case can be controlled either manually or automatically, and manual control can be literally manual (such as with a lever) or electronic, with a button. In general, the more automatic the system is, the more expensive, fault-prone, and heavy it is as well.