How does Anti-lock Braking System (ABS) work?

ABS uses wheel speed sensors to detect when a wheel is about to lock during braking. When impending lock is detected, the hydraulic control unit rapidly modulates brake pressure (typically 15-20 times per second) to that wheel, releasing and reapplying pressure to maintain optimal slip ratio (10-20%). This prevents wheel lockup, maintains steering control, and often reduces stopping distance on slippery surfaces.