What are Anti Lock Brakes?

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  • Written By: Ken Black
  • Edited By: Bronwyn Harris
  • Last Modified Date: 18 September 2019
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Anti lock brakes are vehicle brakes used as part of a comprehensive braking system that is meant to aid in stopping cars, trucks and other types of automobiles in emergency situations. The brakes function by preventing the braking system, in most cases, from completely locking up the tires. They are meant to prevent a car from skidding, which not only negatively affects directional control but also stopping control.

The vast majority of new cars now have anti lock brakes installed as a standard vehicle safety feature. The fact that they are considered far safer than traditional brakes also means that cars that feature them are usually given a discount on auto insurance rates. However, the more important reason to have these brakes is because of the control they provide in emergency situations.

When an unexpected situation comes up, drivers often go into panic mode. In this situation, the first instinct is to stop the vehicle as quickly as possible, in most cases. To do that, they often press has hard as possible on the brakes in an instinctual reaction. In the the past, with traditional braking systems, this would cause the brakes to lock up. Anti lock brakes ensure that does not happen, or at least does not happen as often.


This type of brake operates under a very complex system, and some would say that once the system is actively controlling the situation, it is out of the driver's hands. The electronic control unit monitors the rotation of the wheels and when a difference in the rotational speeds of the wheels is detected through the use of sensors, it will act to decrease the braking pressure on those wheels rotating slower, thus naturally speeding up their rotation.

The idea behind anti lock brakes is similar to the idea of "pumping" the brakes in traditional braking systems. Pumping the brakes helps keep the rotational speed of each wheel in sync. However, with this type of brake system, pumping should not be done, simply because you are working against what the brakes are already trying to do.

Despite the fact that anti lock brakes are widely used and considered an indispensable safety feature in many vehicles, there are conflicting studies about their actual effectiveness. An Australian study suggests they do help reduce multiple-vehicle crashes significantly. However, a study by the Insurance Institute for Highway Safety suggests that they do not reduce the risk for a fatal accident.


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Post 8

Oh anti lock brakes how I love thee! I do not know what parts make up anti lock brake parts, but I love each and every part.

I can remember learning to drive on my parents car and having to stop suddenly. What happened? I slammed on the brakes, naturally.

What then happened to the car? Skidding but not stopping, naturally.

Luckily there was room for me to go to the right of the road and so I took the poor car and my poor mother for a little ride in the grass. I think we had to get a crow bar to get her hand off of that handle that hangs above the passenger side window.

Fast forward many years and when I had to stop suddenly I felt the brakes pump underneath my slammed foot and next I feel the car come to a stop. No trip to the other side of the road trying to skid to a halt. No mom trauma.

Do anti-lock brakes stop fatalities? Maybe not, as the article mentioned the safety report that found evidence to prove otherwise. But do anti lock brakes work by stopping bumper-to-bumper collisions that cause injuries and significant traffic... I think so!

Post 7

I have heard that stopping with anti lock brakes while driving on fresh snow or loose gravel can actually take longer than with traditional brakes. I’m glad I found this out before the rare snowstorm we had last winter.

I live in the South, where we’re lucky if it snows two inches all season. Last winter, we got about 12 inches. Drivers were having accidents by the hundreds, because nobody was familiar with driving on so much snow.

I left work early that day. I remembered not to follow too closely behind anyone, because my anti lock brakes could take awhile to totally halt my car.

I was coming up on a vehicle at a traffic light

, and I tried to stop. Sure enough, I could feel the car sliding forward further than it should have. I had allowed extra distance for this, though, so I still had about six inches between my car and the car up ahead when I did come to a full stop.
Post 6

I wish I had more confidence in the power of my anti lock brakes. I have had to stop suddenly many times, but I am afraid to push the brake all the way to the floor. I push it most of the way, pause, then push it some more.

I think I am afraid that stopping the car so abruptly will cause the airbag to come out. I know that it’s only supposed to rise up when you hit something, but stopping when you are going 60 mph could make it think that you have collided with someone.

Post 5

I love my anti lock brakes, because I am one of those people who brakes for animals. I don’t discriminate, either. I brake for possums, squirrels, and even little birds.

My neighbors down the street own guineas, and they sometimes wander out into the road without much warning. It’s nice to be able to stop suddenly without losing control.

Neighbors even further down have a dog that chases cars. At first, I slammed on the brakes hard for him, because I thought he was simply running out in front of me. My car stopped so suddenly that it startled both of us.

Post 4

@indemnifyme - I hope not! I need all the discounts on my insurance policy I can get. I have the anti-lock brake discount as well as a few other ones.

I've actually never had a car that didn't have anti-lock brakes in it, but I have ridden in a few. Once when I was a teenager I almost got into an accident in a friends old Buick that didn't have anti-lock brakes. Luckily no one was around when we spun out of control on the road but it could have been much worse.

Post 3

I'm kind of surprised that insurance companies still give discounts for anti-lock brakes if Insurance Institute for Highway Safety says they don't reduce risk.

Insurance companies are all about risk, reducing risk, and calculating risk. Normally they don't give discounts unless something is proven to be a risk reduction. I wonder if we'll start seeing this discount go away sometime soon?

Post 2

I've always driven older cars and I just got my first one with anti lock brakes. I'm definitely enjoying the car insurance discount! But I'm not sure totally sure how to use anti lock brakes. Is there anything to know besides just press them as hard as you want to?

I've been driving for a long time and I've gotten so used to pumping the brakes. I can certainly see how a computer could do a better job of that. Any advice for an ABS newbie?

Post 1

My husband was once in a serious single-vehicle accident that anti-lock brakes may have prevented. At the time, he was twenty-two but had been driving for only two years. (His mother could never afford to add him to her car insurance.)

He drove an old Toyota that did not have anti lock brakes. He had to stop short in the rain and he didn't know that he was supposed to pump the brakes! So he slammed on them, spun out on the wet road, and crashed into a construction barrier.

Fortunately, he was not seriously hurt, though he did require stitches. And f course, his poor old car was totalled.

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