Anti-lock brakes, also known as anti-lock braking system (ABS), have become a standard feature on cars, but they weren’t even originally invented for cars. They were invented in 1929 in France by Gabriel Voisin to help planes more smoothly apply brakes on landing and shorten the distance needed to come to a stop. Today it is an automobile safety system that is mandatory on all new passenger vehicles.
ABS uses wheel speed sensors, a hydraulic control unit, and a computerized control system. When the brake pedal is pressed, the ABS reads the speed of the wheels. If it detects that one or more wheels are about to lock up, the system applies hydraulic pressure to the wheels in question. The rapid application of pressure is like “pumping” the brake, except that with the ABS system the wheel that is locking up is the only one being controlled, the rest of the wheels are free to roll. This helps you maintain control.
The primary purpose of ABS is to increase the driver’s ability to control the car rather than go into a skid. When you slam on the brakes, your car starts skidding and loses stability – and you lose control, especially on wet or slippery surfaces. ABS allows the wheels on a car to continue turning and maintain traction as the driver applies the brakes, preventing the wheels from locking up and preventing uncontrolled skidding. It uses the threshold and cadence braking methods used by skilled drivers, automatically “pumping” the brakes at a much faster rate than a person can, and with better control.
In hard braking on smooth surfaces such as concrete or asphalt, in dry or wet conditions, drivers with ABS equipped cars are better able to stop in a shorter distance and maintain control than drivers in cars without anti-lock brakes. In testing, only the best seasoned drivers are able to come close to the performance of ABS.
When the ABS is engaged you will experience a few things:
- The brake pedal might feel harder to press.
- The braking process itself can feel like a rapid pulsing or vibration in the brake pedal.
- There will be some noise, such as a clicking or ratcheting sound. Some systems might emit a buzzing or humming sound.
- It might feel like your car is skidding, but it is not – as evidenced by the fact you can still steer.
- Your tires might leave some marks, but should not “flat spot.” This is when there is a flat area on the tread of the tire that disrupts its roundness and creates a very bumpy drive. Generally, you have to replace the tires when flat spotting occurs.
If you’ve never driven a car with ABS, or experienced the effects of anti-lock brakes as they do their work, it can be a real surprise. It’s a good idea to find a safe place, such as an empty parking lot, to get acquainted with your ABS, so you know what to expect in a hard braking situation.
Even with an ABS equipped car, remember to drive safely and keep your car well maintained. Always keep a safe stopping distance from the vehicle ahead. Don’t consider ABS a safety blanket in bad weather. Always slow down and exercise extra caution. ABS will not stop your car on a dime, and you can still lose control due to driving conditions, the actions of other drivers, and if you don’t know how to operate your car as the ABS is in action.
Additionally, there are some other things to consider when you have ABS. Keep your tires appropriately inflated for the season/weather and monitor treadwear. Have your alignment checked and, of course, maintain your brakes with regular inspections and service to ensure they are in top working condition Fluids such as brake and steering should be checked with every oil change.
Things to remember when driving a car with ABS:
- Do not pump the brakes if you have ABS. Hold your foot firmly on the brake pedal and try to remember that you can still steer (a benefit of ABS).
- ABS can actually lengthen stopping distances on some surfaces or in some conditions, such as snow, dirt, or gravel. This is due to effects that occur that are unique to those conditions.
- Do not jerk the steering wheel or execute a sharp turn when in a hard braking situation with ABS.
- The main purpose of ABS is not to stop your car faster, but to help maintain vehicle stability, thereby helping you maintain control to possibly avoid uncontrolled skidding and collisions.
After an incident of hard braking you should have your brakes and ABS inspected for any adjustments that might need to be made (check your owner’s manual). Your tires, steering, and alignment should also be inspected, particularly if there was any extreme skidding or a collision.