Brake System Precharging, Basic Function - GF42.47-P-1006A

Model All (4xWD, CAR) 

Overview 

This document contains information on:

• General 
• Function requirements 
• Function 
  • Precharging depending on the accelerator pedal actuation 
  • Precharging depending on the lateral acceleration 

General 

Precharging of the brake system serves to ensure that the required braking power for the driving situation is reached faster and that the braking distance is shortened.

Function requirements 

• Drive train operational
• Engine in operation
• Brake and traction system functional

Function 

Precharging depending on the accelerator pedal actuation 

If a supposed emergency braking situation is detected, the brake linings are applied to the brake disks. The clearance between the brakepad and the brake disk is reduced before the driver operates the brake pedal. This means that the service brake's response time is improved and the braking distance is shortened.

Emergency braking is detected on the basis of the release gradient of the accelerator pedal. If it is detected that the accelerator pedal has been quickly released, the system assumes that the driver intends to brake. Precharging is activated and a brake pressure of 2 bar is requested.

In order to adjust the activation threshold of the precharging function to the individual driving style, the average accelerator pedal withdrawal speed is determined.

Precharging depending on the lateral acceleration 

During dynamic cornering, the brake linings are applied to the brake disks on the two outer wheels with a brake pressure of 1 to 2 bar. As a result, the clearance between the brakepad and the brake disk is reduced.

In the case of intervention by the ESP®, the braking power required for the driving situation is reached faster and the braking distance is shortened.