Traction or tractive force is defined as the tire adhesion to the road surface. There are three types of traction forces:
- Traction Acceleration – to accelerate the car
- Brake Traction – for slowing or stopping the vehicle
- Traction turn or Adherence cornering – for changing the direction of the car
In case the traction forces become larger than the maximum friction, the driver will lose control of his car.
The driver has the opportunity to exercise at any time the three forces mentioned. In a given situation, there will be a certain maximum level of friction (coefficient) available for exercising those forces or actually handling car. When the driver accelerates or brakes during the period of a turn, those forces will compose (gather) and take into account of the maximum frictional force available. In other words, the amount of the acceleration or braking forces and those of the steering should not exceed the maximum limit of of the friction force, otherwise the driver will get the car out of control. It is recommended, as far as possible to avoid braking or accelerating during the period of a turn. This enables exploiting full potential of friction strict for making a turn.
A spinning wheel can not provide a value of maximum traction in case of accelerating. If a driver causes the wheels to slip during a turn, it has very high chances to lose control of the car.
A jammed wheel provides no steering effect, in addition, generates a low grip when braking. When a driver blocks the car’s wheels in a turn, the car will not respond to commands from the steering wheel. During braking, the maximum coefficient of friction is achieved when is involved a slip of max. 15%.