Dynamic Brake Control (DBC) is an active safety system which improves brake effectiveness in emergency "panic stop" situations.

With DBC, when you need to stop in an emergency, the system reinforces your applying the brakes to provide maximum braking in the shortest distance. The criteria for full brake application are the speed with which you apply the brakes and the amount of brake pressure you exert.

DBC is only activated when the brake pedal is depressed firmly and quickly.

Here's how it works:

DBC works with hydraulic brake pressure reinforcement. The hydraulic unit is part of the Dynamic Stability Control (DSC) system:

DSC allows for the computer controlled application of brake pressure to any or all of the wheels in a manner designed to retain directional stability of the car in emergency situations. The DSC system is usually activated when the car is under power, although it also helps to maintain directional stability when braking while cornering.

DBC, on the other hand, operates only in severe or emergency braking situations, and it is an adjunct to the existing Anti-locking Brake System (ABS) which provides for directional control.

An emergency is defined by DBC on the basis of the rate of increase in brake pressure in the main brake cylinder. Once DBC is activated, the retrieval pump of the hydraulic unit builds up pressure until both vehicle axes are regulated by ABS.

The dynamic braking process begins when you hit the brakes:

A brake pressure sensor records the magnitude and speed of the brake pressure change and the sensor communicates these values to the DBC control unit. The control unit compares the values to its stored DBC activation thresholds. DBC will activate only if the following criteria are met:

• brake pressure in the master brake cylinder is greater than 30 bar
• brake pressure build-up is greater than 6000 bar/second
• vehicle's road speed is greater than 3 mph
• vehicle is not traveling in reverse
• one or more wheels are not in the ABS regulation range.

If all of these conditions are met, DBC activates. DBC deactivates when the driver releases the brake pedal or if the vehicle slows down to less than 3 mph.

The application of all of the stability and braking systems, including DBC, is coordinated by a system called Electronic Brake Management (EBM). 

BMW Dynamic Brake Control Further Increases Safety press release.

BMW AID page on DBC.

BMW Dynamic Brake Control article from Autoweb.

BMW South Africa informative page on ABS and DBC.

BMW Thailand informative page on DBC and other technologies used in 7 Series models.

HydroAire makes brake components for aircraft. Click here for an Acrobat tutorial on anti-skid brakes. Many of the concepts apply to motor vehicle emergency braking.

Motorola and BMW take driving to another level describes BMW's partnership with Motorola, a supplier for automotive semiconductors.

Dynamic Brake Control news article from Canadian Driver.