What Is ABS and How Does It Work?

We take braking for granted these days. Cars used to be huge, heavy, and severely under-braked. Back then, drum brakes were the norm, as were skinny, tall tires with minimal traction that provided a comfy ride. There was a reason old American cars had wide brake pedals (for both feet, obviously), and the old saying of “pump the brakes” existed: Stopping used to be a suggestion, not a certainty. Thankfully, things have changed. A lot of that change is thanks to anti-lock braking systems.

ABS is meant to help drivers maintain control of their vehicles in emergency situations. Before ABS, cars would simply lock the wheels under hard braking, and drivers were along for the ride. Now, we can steer under aggressive braking, helping avoid possible crashes and injuries. It’s one of the most critical safety innovations in car history, and it was only invented in 1971. In the years since it has become a mandatory technology on every new car sold in countries all over the world.

But how does it work? It’s a simple, almost ingenious technology that has proven endlessly useful. Let’s dive in.

What Is ABS? 

ABS is an acronym for anti-lock braking system. As part of a vehicle’s stability system, the ABS monitors the driver’s braking pressure and individual wheel speeds. If the system detects that one or more wheels are rotating too slowly relative to other wheels, it will cause a short release of brake pressure on the affected wheels to allow rotation to continue and safely stop you in the shortest amount of time. The system is optimized only to release when the wheel is about to lock up, or when the wheel is no longer rotating and the tire is skidding across the road surface.

When hard braking causes a lockup, the vehicle will continue traveling in whatever direction it was headed when the lockup and resulting skid began, no matter which way the driver turns the steering wheel. Also, during a lockup the brakes are no longer doing the work of stopping the car. It’s the friction of the tires skidding, which has much less decelerative potential than using the brakes properly. In effect, the tire is severely overloaded and can no longer do other work other than skidding.

ABS helps prevent this problem by pulsing the brakes to allow just enough wheel rotation for the driver to retain control of the vehicle. The system releases braking pressure tens of times per second, and the driver may feel a vibration or pulse in the steering wheel as it’s happening.

In late 2013, the National Highway Traffic Safety Administration mandated ABS, along with electronic stability control (ESC). Vehicles made in the U.S. since then have been required to carry the technology.

Simply put, ABS is one of the most significant innovations in vehicle safety and performance since the radial tire or the seatbelt. It helps the everyman stop like a racing driver, but most importantly, helps everybody get home safely in emergency situations. With ABS, maintaining control of cars is much easier. Without it, you would have to actively think about how and when to brake. That’s difficult when there’s a deer in the road, or a car parked where it shouldn’t be.

Hopefully, most folks will never have to use ABS. But the vast majority of cars on the road are equipped with it. When the time comes and you need to stop now, be sure you’re in a car with ABS. It could save your bacon.