The anti-lock braking system is designed to prevent wheel lock during heavy braking.
The main functions of ABS:
- reduction of the braking distance due to the elimination of wheel blocking during intensive braking;
- improving the stability of driving during braking.
The anti-lock braking system works based on information from four sensors transmitted to the ABS unit. The system controls each wheel individually and reduces the fluid pressure in the wheel brake mechanism, the wheel of which begins to block.
Under normal conditions, the standard brake system applies the brakes until a wheel lock is detected by the ABS control unit. During normal braking, the intake valves usually open and the exhaust valves usually close.
When the ABS control unit detects a blocked wheel, it controls each valve to increase or decrease the pressure.
The ABS control unit determines the speed and deceleration rate of each wheel based on information from the wheel speed sensors. When braking, the wheel speed decreases and the ABS unit detects the difference between the vehicle speed and the wheel speed. If the deceleration of some wheels exceeds the expected value, the ABS unit detects the start of a blockage and opens the appropriate solenoid valves to reduce the brake fluid pressure. In this case, the wheel speed increases and the pressure relief solenoid valve closes and the brake fluid pressure in the working brake cylinder of the corresponding wheel increases.