Friction Circle Theory (Kamm)
This theory about the transferable forces from the tire to the road surface goes back to Wunibald Kamm. After several years of activities at Daimler and other industries, he founds the Research Institute of Automotive
Engineering and aircraft engines at the Technical University of Stuttgart, as it was named in the 1930's. Later this institute with the first wind tunnel for full vehicle size was taken over by Daimler-Benz and developed.
The arrow from the center of the tire contact area to the circular line symbolizes the possible total force. If the vehicle goes straight and no lateral forces take effect, then the maximum possible acceleration or braking
force is possible. If this, however, is fully utilized, the contact between tire and road surface is influenced by slippage.
Lateal support is no longer possible. A rear driven car accelerating with maximum possible torque you could theoretically push away laterally by manpower. Sometimes you can even see that a vehicle in such a
situation breaks out and must be kept on course by appropriate steering manoeuvers.
Conversely the transmittable force in or against the driving direction shrinks the more lateral forces on the tires are effective. Applied to systems such as ABS, this means a fully braked wheel no longer follows a
steering pulled aside.
The situation at the motorcycle is not fully comparable. Here the cornering is recovered principally through inclination. Vertical downward acts the weight force and horizontally to the outside the centrifugal force. If with
wider tires the contact point moves more to the inside, more steep sloping position is needed, as to be seen at racing machines. 03/16
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