<div class="htmlview paragraph">In order to define a suitable drive concept for four-wheel drive vehicles, the basic relationships between road adhesion, wheel load distribution and drive torque distribution are discussed with the aid of simple models, and compared with the characteristics of a four-wheel drive system employing a Torsen centre differential. Taking the example of acceleration in a straight line, it can be shown that the basic 50:50 % torque split inherent in the design is altered by the Torsen centre differential, to give the ideal torque split for that particular driving condition. The significance of this fact for handling response in more complex situations, such as accelerating and braking in a corner, is shown with the aid of simulation calculations with realistic vehicle models and measured data obtained from vehicle testing.</div>