Anti-Lock Braking System (ABS)

Anti-Lock Braking System (ABS)
The ABS components are combined with an hydraulic booster and a tandem master cylinder to provide a two circuit braking system. The system comprises, four wheel speed sensors, a brake control modulator and an ABS warning lamp.

Should a wheel start to lock-up during braking a signal transmitted from the wheel speed sensor to the brake control modulator will start the hydraulic pump. The brake control modulator will close the input valve of the line connected to the locked-wheel to stop any increase in fluid pressure to the brake caliper. If this fails to prevent the wheel locking, the pressure in the caliper will be decreased by opening the return valve until the wheel starts accelerating again. The fluid pressure from the return valve is directed into the low pressure accumulator, housed in the pump.

From the low pressure accumulator, fluid is pumped through the damping chamber to the brake master cylinder. The pressure to the brake caliper will then be increased in small steps to maintain maximum adhesion between the tire and road surface. This is achieved by closing the return valve, and opening the input valve and using the hydraulic pump to increase the pressure.

Although the system senses all four wheels independently, the rear wheels are regulated as a pair. If a sensor on a rear wheel detects a wheel decelerating rapidly, then the fluid pressure to both wheels is reduced. The fluid pressure is then dictated by the wheel having the lowest adhesion with the road surface.

The ABS system will be set in a fail-safe mode if a problem is detected; a warning lamp on the instrument panel will notify the driver there is a problem. The brake system will still operate conventionally and with the same standard of performance as a vehicle not equipped with ABS.