1112 Brake stopping distance and efficiency

Braking implies producing a force which opposes the motion of the vehicle's wheels, thereby reducing the vehicle speed or bringing it to a halt. The force or resistance applied to stop a vehicle or reduce its speed is known as the braking force.

The braking efficiency of a vehicle is defined as the braking force produced as a percentage of the total weight of the vehicle, that is

Weight of vehicle

When the braking force is equal to the whole weight of the vehicle being braked, the braking efficiency is denoted as 100%. The braking efficiency is generally less than 100% because of insufficient road adhesion, the vehicle is on a down gradient or the brake system is ineffective.

The brake efficiency is similar to the coefficient of friction which is the ratio of the frictional force to the normal load between the rubbing surfaces.

i.e. Coefficient of friction = Fricti┬░n force

Normal load

Fig. 11.1 Illustration of braking conditions i.e.

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