How to Use Anti-Lock Brakes: Understanding the Principles

keep your foot on the brake. Maintain firm and continuous pressure on the brake while steering . If your vehicle is equipped with just rear-wheel anti-lock brakes, however, the front wheels can still lock up. If that happens, ease up on the brake pedal slightly to allow the front wheels to roll again so you can steer.

Almost all modern vehicles use an anti-lock braking system (ABS), which prevents accidents by allowing drivers to steer properly and reducing braking distance. But what exactly is ABS, and how does it prevent accidents?

To understand ABS, it’s important to first understand the principles of steering and braking. When you apply the brake pedal, brake pads on the wheel disks will activate and press against the disks, stopping the wheel rotation and causing friction between the road and wheels to stop the vehicle. The steering mechanism, on the other hand, depends on the simple principle of wheels rolling. The wheels rotate on their axis and move along the direction of the car. For non-slip rolling conditions, the sum of the translational and rotational velocities at the contact point should be zero.

In automobiles, all four wheels should be rolling at all times to avoid the vehicle slipping. If the wheels are turned but the car carries straight on, the car will slip. The translation velocity needs to be inclined to avoid this, which is possible when the whole car makes a turn. When the car makes a turn, all four wheels can satisfy the condition of rolling, and the velocity at the contact point of all four wheels becomes zero.

During braking, due to the brake pads being activated, the wheels stop spinning. Even if the wheels are turned, since they are not rotating, there will be no rotational velocity. Therefore, the vehicle does not need to turn, and the vehicle will slide in a straight line, which can cause an accident. Apart from losing control of the steering, cars without ABS face another big issue of braking on surfaces with different traction levels. When the left and right wheels are on different traction surfaces, applying the brakes will generate different frictional forces on the wheels, producing torque, and the car will go into an uncontrollable spin.

This is where ABS comes in. ABS prevents the wheels from completely locking up by partially releasing the brake pad on the wheel when the speed sensors detect that a wheel is about to lock up. This way, the wheels will be allowed to spin intermittently during braking, allowing steering to function, and drivers will be able to steer the vehicle even during braking.

The key benefit of ABS is reducing the braking distance. The frictional coefficient between the tire and the road varies with respect to slip. During braking without ABS, the frictional coefficient which comes into effect is predominantly sliding friction. However, in ABS braking, the clever algorithm adjusts the brake pressure to keep the slip ratio near to 12%, where the frictional value is at the maximum. This significantly reduces the braking distance.

In addition to reducing braking distance, modern ABS also includes intelligent electronic braking distribution (EBD), a subsystem that measures the yaw rate of the car and the relative slip of each wheel. By reducing brake pressure on the wheels with higher grip, we can reduce the frictional force produced by these wheels, keeping the yaw torque and the whole car under control.

In conclusion, ABS is a crucial system that all drivers should understand. By understanding its principles, you can see how it prevents accidents and reduces braking distance. So the next time you’re on the road, remember, ABS can make all the difference.


How should you use anti-lock brakes when?
When driving an ABS-enabled vehicle, there is no need to pump your brakes. Your ABS will automatically pump the brakes the moment it detects wheel skid. All you need to do is apply firm, steady pressure to the brake pedal. The pedal should then pulsate while the ABS light illuminates.
How does anti-lock brakes work?
In an anti-lock braking system, your car's wheel speed is monitored and if wheel lock is detected, a sensor sends a message to a controller that releases and applies the brake up to 20 times per second, preventing a lock up and helping you maintain control of your vehicle.
Do you pump your brakes with anti-lock brakes?
Therefore, according to the experts: You do not have to pump your brakes. In fact, if you pump them while braking hard, you will lose the benefits of the ABS. During emergency hard braking, apply firm pressure to the brake pedal, do not take your foot off the brake until your vehicle comes to a full stop.