Antilock Brakes / Traction Control Systems: Description and Operation

Fig. 1 Anti-Lock Brake System:

The Anti-Lock Brake System (ABS) functions by releasing and applying fluid pressure to wheel cylinders during braking, Fig. 1. During normal driving conditions the system does not function and has no effect on front to rear brake proportioning. When one or more wheels approaches a slip condition. The ABS automatically senses the slip and activates the pressure control function.
Through pre-programming, the control unit decides which wheel or wheel`s brakes pressures need modulation. The control unit sends appropriate signals to solenoid valves located in the actuation assembly. The control valves then modulate fluid pressure which results in a pressure reduction at wheel cylinder to prevent further lock up.