What Is ABS?
This now-ubiquitous braking system does a lot of work for you.
Shutterstock
Article QuickTakes:
ABS stands for anti-lock braking system. ABS is one of the foundational safety features of a modern automobile, forming the basis for many other technologies and capabilities.
Safety systems may not get the same attention in marketing materials as powertrains and styling. Still, these systems are among the most essential features of modern cars, helping keep occupants and others safe. ABS allows for more stability during extreme braking, which in turn helps drivers perform evasive maneuvers when necessary.
What Does ABS Do?
Cars need ABS to maintain traction when skidding. Tires provide traction to the road surface; if they stop spinning, they'll stop gripping. And if you want to slow down or even stop, grip and traction are essential.
ABS prevents the tires from stopping completely in hard braking situations, which helps maintain grip and slow the car down safely in poor-traction conditions. That might sound counterintuitive, but it works. If not for ABS, drivers could lose control on slippery surfaces, meaning the car might rotate unpredictably.
Before ABS was a standard feature, instructors advised drivers to press and release the brakes quickly (also known as pumping the brakes) whenever they felt a loss of traction, such as when driving on snowy or rainy roads. This action would allow the car to slow to a stop without locking up the tires and losing traction. ABS pulses the brakes much quicker than a human can, allowing the driver to focus on the road ahead and avoid an obstacle.
The feel of ABS and the noise that occurs when it kicks in can be a bit disorienting, but drivers should keep their foot firmly on the brake pedal for it to keep working as it brings the vehicle to a stop.
How Anti-Lock Braking Works
ABS relies on speed sensors. These sensors detect the rate each wheel is spinning and whether one wheel is going faster than another, such as when slipping on a low-traction surface or if the wheels have locked up.
As a hydraulic system powers brakes, ABS uses special valves that can open and close rapidly to apply and release pressure to the brakes quickly. So, when the sensors detect slippage or a lockup, they tell a hydraulic modulator to activate those special valves and pump the brakes.
The Advantages of Anti-Lock Braking
The most significant advantage of ABS is that it helps decelerate and stop a car that might otherwise be sliding on locked wheels. However, ABS also plays a part in other critical safety systems. For example, electronic stability control (ESC) helps prevent sideways skidding using the same speed sensors and hydraulic braking modulator as ABS. Traction control also uses these systems to operate and keep occupants and others safe in poor road conditions. Some torque-vectoring systems rely on ABS to direct power to the outside wheels during a turn, subtly improving cornering performance.
ABS is so significant for safety that it is federally mandated in every new car on sale today as part of the required ESC system.
