ABS System

Why are ABS System Part Important

The Anti-Lock Braking System (ABS) is a complex network of subsystems that take over control of your brakes in a lock-up situation (when the wheels stop faster then the vehicle) to minimize skidding and maximize vehicle control. ABS system keeps you safe in two ways: pulsing brake pressure on and off stops the vehicle faster than locking up the brakes—especially in slippery road conditions; At the same time the ability to steer around danger is maintained when the wheels are kept spinning.

Maintaining this system of mechanical, electronic and hydraulic components takes the pressure off your brake system’s hardworking components such as brake pads, rotors and—the most abused member of the team—the tire.

This modern Anti-Lock System takes the place of two competing techniques from the “good ole days”: the Stomp and Pray and the Pump.

The Stamp and Pray technique is pretty self explanatory: pin the brake pedal to the floor, lock up the wheels (cease all rotation), and pray you stop in time. The Pump technique is a little more advanced. The driver increases pressure on the brake pedal until the wheels skid and then releases pressure until the wheels rotate again. This repeats until the car is stopped. This way, the skid is minimized while the momentum-reducing deceleration is maximized. It not only yields a quicker stop but also maintains the ability of the driver to steer through the process.

The Pump technique is the distant and primitive root of the modern ABS which can engage and release the wheel up to 16 times per second. In addition, recent versions use sensors to monitor and proportion braking individually to the four wheels so that each corner of the vehicle is coordinating to reduce momentum of the whole. Pretty advanced stuff for something that was introduced to the American market in the 1970s.

There are four main components to an ABS system: a controller, a pump, a valve, and speed sensors.

Controller

Typically, a computer unit receives data from sensors and sends signals to the ABS controller in order to engage or disengage brake pressure. In addition, the controller can activate the ABS modulator which engages ABS pulsing to any or all wheels.

Pump and Valve

The pump raises pressure to the brakes when the ABS system is engaged while the valve releases it. Not active during normal brake actions, the two components work in tandem to rapidly increase and decrease pressure to the brakes in order to create the pulse effect that applies maximum braking with minimal skidding.

The valve has three distinct positions. First, it can be fully open in which pressure from the master cylinder is uninterrupted and the brake pedal controls the braking force. Secondly, it can be fully closed in order to cut off the master cylinder to the effected brake. At this point, increased brake pedal pressure will have no affect on the that wheel. Lastly, it can be partially open in order to release some pressure.

Speed sensors

Located at each wheel and/or in the differential, these sensors gauge wheel speed in order to react to a lock up. The information is then sent to the ABS controller.