Four-wheel disc antilock brake system


Four-wheel disc antilock brake system

Automobiles have come a long way. Modern cars are much safer than those manufactured during the early 1900s. Those being built today are equipped with a range of advanced features developed to help drivers and passengers steer away from certain safety issues.

An anti-lock braking system or ABS is one such capability. It is essentially an anti-skid braking system that works by preventing the wheels of the vehicle from locking up while slowing down. This avoids uncontrolled skidding. Anti-lock braking systems are highly effective and operate at a much faster rate than a human driver could manage. When using ABS, the braking distance on loose gravel and snow-covered surfaces are more than that on slippery and dry terrain.

That said, ABS can help improve steering control on these roads. The latest versions of ABS not only prevent the wheels from locking but can also alter the front-to-rear brake bias.

Components of an ABS
There are four main components of an ABS. These are as follows:

Valves have the responsibility of controlling brake pressure. On a select few systems, the valve has three positions.

  • Position 1 - In this position, the pressure from the master cylinder is directly transferred to the brake.
  • Position 2 - The valve blocks the line. This separates the brake from the master cylinder, ensuring that the pressure does not further if the driver pushes the brakes harder.
  • Position 3 - In this position, the valves work to release some pressure from the brake.

The ECU type unit receives information from the speed sensors. When a wheel loses traction, the controller receives a signal and activates the ABS modulator while limiting the brake force immediately.

Speed sensors
Speed sensors of an anti-lock braking system study the acceleration and deceleration of the wheels. While some speed sensors use a magnet and a Hall effect sensor, others utilize a toothed wheel and an electromagnetic coil. The primary function of a sensor is to accurately determine when a wheel is about to lock up. Speed sensors are usually not accurate at low speeds.

Every ABS has a pump that comes into play after the valves have released the pressure to the hydraulic brakes. It works to restore the desired amount of pressure to the braking system.

Source: Dodge