Brakes
Brakes are primarily used to decelerate a vehicle beyond its road resistances and the braking effect of the engine. Kinetic energy of the vehicle is then transformed into heat. Besides this principal form of employment, the task of brakes also consists in keeping the vehicle at standstill or (in downward gradients) at a constant speed.
Generally, the braking systems in a vehicle can be classified as follows:
Service brake system: General decrease of speed in normal driving
Emergency brake system: Takes over the function of the service brake when it fails
Parking brake system: Prevents unwanted rolling of a parked vehicle
Continuous service brake system: For longer uninterrupted braking and frequent stops (public busses).
The service, emergency and parking brake systems directly work on the wheel brakes. Brake elements of the continuous service brake system generally exert their decelerating moment on the drive train.