What Are Anti Lock Braking Systems (ABS)?

2/4/2021

Key Points

  • Anti-lock braking systems (ABS) are now standard on almost all new cars and motorcycles, improving vehicle safety.
  • ABS prevents the wheels from locking up when braking, preventing skidding and loss of control.
  • ABS was first tested on railway cars and aircraft in the 1950s and was implemented in cars in 1978.
  • ABS works by using speed sensors, valves, a pump and a controller to monitor and control brake pressure.
  • ABS has been proven to reduce crash rates and fatal collisions but may be less effective in extreme weather conditions.
  • Automotive technicians need to understand ABS to diagnose and repair vehicles.

Have you ever been driving down the road and suddenly had to hit your brakes to avoid a collision? This can be scary, but it is something almost everyone has encountered at one time or another.

Thanks to anti-lock braking systems (ABS), today’s vehicles are safer than ever before. ABS is now standard on almost all new cars and motorcycles, and it helps with traction control and the driver’s ability to steer while braking.

So, what exactly are anti-lock braking systems, and how do they work? Keep reading to learn all about these systems and what automotive technicians need to know.

What Is ABS?

No matter how good of a driver you are, you’ve probably had to step down hard on the brake pedal to avoid a collision. When this happens, the wheels of your car can lock up, preventing the vehicle from stopping.

As a result, the wheels can lose traction and cause the vehicle to skid across the road. It can also cause the driver to lose the ability to steer, resulting in the vehicle spinning out of control.

Anti-lock braking systems, which are also referred to as anti-skid braking systems, are designed to prevent this from happening. Essentially, they keep a vehicle’s wheels from locking up when braking.

When Was ABS Invented?

Anti-lock brake systems were first tested on railway cars and aircraft in the 1950s. Around this time, the braking system was also implemented on motorcycle prototypes to help prevent skidding and loss of traction.

By the 1960s, the system was used on the world’s first four-wheel drive Formula One car. From here, Daimler and Mercedes-Benz began working on a system that could be applied to cars. After much trial and error, Mercedes-Benz revealed the technology at a Daimler test track in 1978.

From then on, anti-lock braking systems were implemented in more and more cars. Today, it’s a standard in almost all cars — and it's safe to say ABS has greatly improved the safety of the roads we drive on.

How Do Anti-Lock Brakes Work?

At this point, you might be wondering, “How do anti-lock brakes work?” To better understand the answer to this question, let’s break down the main components of anti-lock braking systems:

Anti-lock braking system graphic

Image Credit: How Stuff Works

  • Speed sensors: Detect how fast the wheels rotate.
  • Valves: Located in the brake line, these stop and release pressure on the brakes.
  • Pump: Applies pressure to the calipers, or brake drums, and are filled with hydraulic fluid.
  • Controller: Takes data from the sensors and controls when to pump the brakes.

Not all anti-locking braking systems are the same, but they generally work by pumping the brakes when the driver is heavily braking. The sensors on the wheels help monitor when the brakes are applied and then will release and reapply the brakes to prevent locking from happening.

How Effective Are Anti-Lock Brakes?

According to a 2009 report from the U.S. Department of Transportation:

  • ABS reduces the overall crash-involvement rate by 6% for passenger cars and 8% for LTVs (light trucks, including pickup trucks and SUVs)
  • Fatal collisions with pedestrians, bicyclists or animals decrease with ABS: by 13% for cars and 14% for LTVs
  • Culpable fatal involvements with other vehicles on wet, snowy or icy roads were reduced by 12% for passenger cars

Additionally, according to the Insurance Institute for Highway Safety (IIHS), the rate of fatal crashes is 22% lower for motorcycles equipped with ABS than for the same models without them.

One thing to note is that while anti-lock braking systems have proven to be very effective in normal road conditions, they can be less effective in certain conditions, such as if there is ice, snow or gravel on the road. These elements can bring additional challenges and make it harder for the vehicle to stop, even with ABS.

When driving during extreme weather, it’s important not to assume ABS will work exactly the way it would in normal conditions. Always exercise caution by driving slowly, allowing more room for the vehicle to stop, and paying close attention to how your car is reacting to the road.

How To Tell if Your Car Has an Anti-Lock Braking System

Electronic stability control (ESC) became mandatory for all new passenger vehicles in 2012. ESC is a technology that detects and minimizes traction loss, so it should be no surprise that ABS plays a significant role in ESC.  

With that said, most vehicles nowadays have ABS. If you have a vehicle model older than 2012, check your dashboard for an “ABS” light upon start-up. If you don’t notice one, your car may not have anti-lock brakes. To be sure, you can always review your owner’s manual or ask a trained automotive technician. 

What Might You Feel When ABS Brakes Are Activated?

Most anti-locking brake systems require a speed of 12-15 mph to activate. They kick in when the driver slams on the brake pedal suddenly. 

Once activated, the driver may feel the pedal pulse rapidly, almost like it's pushing back against their foot. Drivers may also notice a grinding or buzzing sound, a bit of vibration from the front of the vehicle and a somewhat harsh stop. 

What Automotive Technicians Need To Know

It’s important for automotive technicians to understand all of the different components of modern-day vehicles, including anti-lock braking systems. This allows them to diagnose, maintain and repair the vehicles they work on, which helps keep their customers safe on the road.

Some automotive technicians choose to train for their career on the job, but many employers prefer to hire those who have completed a formal training program, like UTI’s Automotive Technology program.1

Over the course of just 51 weeks, students in this program are taught everything from engine service and repair to service writing, electronic systems, powertrains and transmissions.7 Students also take a course that exclusively focuses on vehicle brake systems, where they learn to diagnose anti-lock braking systems.

Completing an automotive training program can help open the door to a variety of career opportunities, whether it be at a dealership, repair facility, rental agency or even a race shop. If you love working with your hands and solving problems, this might be the right career path for you.

Anti-Lock Braking System FAQs

How are anti-lock braking systems different than other types of brakes?

ABS is not a type of brake but rather a braking system. Most cars have disc or drum brakes, with disc brakes being the more popular option. Both types of brakes typically include ABS.  

What does it mean when the ABS light is on?

When the ABS light is on it could mean the system is deactivated due to a malfunction that requires a diagnostic check and repair by a qualified technician. Malfunctions can range from damaged sensors to low levels of fluid. 

Is it OK to drive with the ABS light on?

Your brakes will still work if the ABS light is on, but in the case of an emergency stop, your wheels may lock up, making it more difficult to control the vehicle. If your ABS light is on it’s best to visit an auto repair center as soon as possible. 

Learn More About ABS Brakes at UTI

UTI’s Automotive Technology program is available at campus locations across the country and includes a course on vehicle brake systems that teaches students how to diagnose anti-lock braking systems. Classes begin every three to six weeks, so you can get on track toward your career sooner.

To learn more, visit our program page and request information to get in touch with an Admissions Representative today. In the meantime, feel free to check out these helpful resources:

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