Fading Support
High temperatures (>550°C) can occur at the brake discs when brakes are applied over a long period (i.e. brakes applied while traveling downhill) or as a result of multiple "extreme" brake applications (i.e. applied pressure >80 bar). As the temperature of the brake disc increases, the level of friction that can be generated when the brake pads are applied is decreased (coefficient of friction is reduced as brake disc temperature increases), which can result in a diminishing brake effect (fading).
In order to reduce the brake "fading" effect the DSC system (MK60E5) calculates the temperature of the brake discs, based on:
- Applied brake pressure
- Duration of brake application
- Rate of vehicle deceleration
In the event the DSC system detects fading, brake pressure is increased in line with the calculated temperature model in order to maintain a constant ratio of brake pedal force to vehicle deceleration (if necessary, pedal travel is increased to compensate for the fading effect).
The DSC system detects fading as follows:
- DSC compares the current vehicle deceleration with a nominal value based on the current brake pressure.
- DSC increases brake pressure until the nominal deceleration is achieved or until all wheels are subject to ABS control.
- Process is ended when the brake pedal is released.
At the time this function is activated, a Check-Control message (brake warning light) appears in the LCD display in the instrument cluster (warning threshold 1). If the brake disc temperature increases further, the legally stipulated brake warning lamp is also activated (warning threshold 2).