How quickly can you react? Really. If your life and the lives of your passengers were on the line, how fast is your foot? In contrast to outdated automotive braking habits, Anti-Lock Brakes (ABS) serve to protect you and your precious cargo by keeping your car in your control. If you have ever stomped on your brakes and experienced a startling growl and a pulsing pedal, you know what Anti-Lock Brakes (ABS) feel like. But what is that growling, rumbling, clicking sound? What is your brake system doing? And what, if anything, should you do so that the ABS will work the way it should?
What is ABS?
Your brake system relies on friction to slow and stop your vehicle. When you press on the brake pedal, a hydraulic pump forces fluid to the brake calipers, hydraulic clamping mechanisms located at each wheel. The calipers squeeze your brake pads against the sides of spinning metal discs (brake rotors) attached to the wheels. You hit the brakes, the calipers clamp down on the rotors, and the kinetic energy of your moving vehicle is converted to thermal energy, which, in turn, safely brings you to a stop.
But when you brake suddenly in an emergency, or on a slippery or uncertain surface, your wheels lock up and your tires begin to skid. When that happens, the amount of tire that is in contact with the road is reduced to a small patch of rubber. Traction diminishes significantly and your car careens in the same direction you were traveling. No matter what you do with the steering wheel.
Not only does your car fail to stop when it is skidding, more importantly, you lose the ability to steer. For your steering wheel to have any effect, your tires need to be rolling. Imagine if you tried to steer with your car standing still. Sure, you can turn the wheel all you want, but the car will not head in that direction. No, the tires actually need to be moving. While that might seem like an oversimplification (it is), in a similar way your steering has no effect if the tires are simply seized up and skidding ahead.
Your ABS is a computer-controlled safety system designed to prevent your wheels from locking up when you brake, no matter what surface you are driving over.
How does your ABS work?
In addition to the ABS computer control module, other specialized components are at play in the system. Wheel speed sensors are fitted in or near each wheel hub. Their job is to monitor the speed of each wheel and relay that data back to the control module. When the computer senses that a wheel has slowed down more than the others (a condition that can lead to locking up), it commands a valve to momentarily release pressure to that wheel. Once the pressure has been released, a pump quickly reapplies pressure and reactivates the brakes. It can also slow down a wheel that is rotating faster than its partners.
This rapid process of brake-and-release happens anywhere from ten to twenty times per second. Your tires never stop rotating, but rather maintain traction with the ground at a point ever so slightly before they lose grip – at the optimum point to slow you down as quickly and safely as possible.
But stopping sooner is not the chief objective of your ABS. In fact, in some driving conditions, it might actually take longer to stop. The true advantage of a vehicle with ABS over one without is the driver’s ability to maintain steering control when braking. Because the wheels do not lock up, they are free to roll in the direction you point them, making evasive maneuvers more likely.
What do you have to do for the ABS to work?
If you want to apply the benefits of technology to your car, sometimes you have to make a deliberate choice. For instance, if you hope for the benefits of synthetic motor oil over conventional oil, you have to select the advanced service when you go in for an oil change. And if you want the smooth, quiet, and clean performance of ceramic brake pads, you have to ask for them to be installed on your vehicle the next time you go in for brake service. But when it comes to ABS, your action is easy.
In the days before ABS, many drivers (skilled ones, anyway) would apply braking techniques that approximated the effect of ABS. One strategy was to press the brake pedal just enough to slow down a vehicle without locking up the tires. A driver would try to “feel” for that point just before the car skidded and hold the brakes there. Of course, that meant that it would potentially take longer to stop, but at least some steering control could be maintained.
Another strategy was a type of cadence braking, where a driver would pump the brake pedal as quickly as possible to keep the tires from locking up and skidding. The hope was that the car would stop sooner and some steering could still be done.
Both techniques had some effect, especially if done by an experienced driver. But in no way can a person respond as quickly and as accurately as the computer-controlled ABS systems featured in today’s vehicles. ABS was designed to utilize similar principles to those old-school techniques but with far superior results. The components of your ABS work in tandem to rapidly pulse your brakes and prevent them from locking up the wheels when you jam on the brake pedal. More of the tire stays in contact with the road; you keep the ability to steer. And you might even stop a bit sooner.
But for the ABS to work properly, it is essential that you work your brakes properly. Fortunately, that is not a difficult task. Though drivers in the past relied on special strategies, it is not recommended that you do that with a modern car, truck, or SUV equipped with ABS.
Instead, simply apply firm and steady pressure to the brakes and let the system do the work for you. If you hear and feel the ABS engage, keep your foot firmly planted on the pedal. Do not ease up significantly. And do not pump the pedal. These efforts will only limit the effectiveness of the ABS. Some drivers find it a bit disconcerting when they first experience the effects of ABS. If that is you – or if you have never had the privilege – you might consider taking your car to a safe area with loose gravel or snow to practice braking with ABS in a controlled environment. Get used to the sound and feel.
Your brakes are the most important safety feature on your vehicle. You would not trust them to the novice neighbor next door nor would you opt for a cheap brake repair service. Neither should you trust outdated ideas as to how to operate your brakes. The system is in place to keep you safe, but it will only work if you let it.
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