Aquaboutic | Focus Security Research | Vulnerability Exploit | POC


how does the abs work?

Posted by melchionda at 2020-04-16

How does the ABS work?

Most people are familiar with the term Anti lock braking system (ABS), but many people know little about the anti lock braking, working principle, special maintenance or replaceable components in the anti lock braking system.

Automobile rubber parts tell you that anti lock brake is essentially an enhanced or improved type of common brake. In short, the ABS is designed to prevent the brakes from locking and slipping when braking on difficult or wet or smooth surfaces. By preventing dangerous taxiing and allowing the driver to maintain steering control when attempting to stop, this adds significant safety to everyday driving. So how do we use it? Let's learn about it with Xiaobian.

Let's see how ABS works first

All ABS systems control tire slip by monitoring the relative deceleration rate of the wheels during braking. If a wheel begins to decelerate faster than the other wheels, or at a faster speed than programmed into the anti lock control module, then the wheel begins to slide and there is a risk of disconnection of traction and locking. The ABS system responds by momentarily reducing the hydraulic braking of one or more affected wheels.

The electric solenoid is used to hold, release, and reapply hydraulic pressure to the brakes. This produces a pulsating effect, which is usually felt in the brake pedal during braking. The driver may also hear a hum or chatter from the ABS hydraulic unit.

The rapid adjustment of the brake pressure in the brake circuit reduces the brake load on the sliding wheel and allows it to regain traction, thus preventing locking. It is the same as the brake, except that the ABS system is automatically completed for each brake circuit, and the speed is impossible for human beings. According to different systems, it can reach dozens of times per second (some faster than other brakes).

Once the deceleration rate of the affected wheel is restored to the same as that of the other wheels, normal braking function and pressure are restored, and the anti lock device is restored to passive mode.

Anti lock brake control module

The ABS electronic control module (which can be called EBCM "electronic brake control module" or EBM "electronic brake module") is a microprocessor whose function is similar to engine control computer. It uses inputs from sensors to adjust the hydraulic pressure during braking to prevent the wheels from locking. The ABS module can be located in the luggage compartment, passenger compartment or under the hood. It can be a separate module or integrated with other electronic devices, such as body control or suspension computers. In the newer ABS system, it is installed on the hydraulic modulator.

The key inputs of the ABS control module are from the wheel speed sensor and the brake pedal switch. When the brake is applied, the switch signals the control module, which changes it from "standby" mode to active mode.

When ABS braking is required, the control module starts to act and commands the hydraulic unit to adjust the braking pressure as required. On systems with pumps, it also supplies power to pumps and relays.

Like any other electronic control module, ABS module is easily damaged by electrical overload, impact and extreme temperature. If there is a defect, the module can usually be replaced, except on some of the latest systems where the module is part of the hydraulic modulator assembly.

Antilock brake pump and accumulator

In some ABS systems, high-pressure electric pump is used to generate power assist for normal braking and reapply braking pressure during ABS braking. In some systems, it is only used to reapply pressure during ABS braking.

The pump motor is powered by a relay that is turned on and off by the ABS control module. The fluid pressure generated by the pump is stored in the accumulator. The accumulator on the ABS system, in which the hydraulic regulator is a part of the master cylinder assembly, which is composed of a pressure storage chamber filled with nitrogen.

If the pump fails (the warning light comes on when the standby pressure drops too low), there is usually enough standby pressure in the accumulator to perform 10 to 20 power assisted stops. After that, there was no power assist. The brakes are still working, but more needs to be done.

On ABS systems with conventional master cylinders and vacuum boosters for power assist, small accumulators or a pair of accumulators can be used as temporary holding containers for brake fluid during the hold release reapply cycle. This type of accumulator usually uses a spring-loaded diaphragm instead of a nitrogen chamber to store pressure.

So what should we do? Here's what to do and what not to do

Millions of cars use anti lock braking systems (ABS), but many drivers still don't know the "right way" to use ABS in an emergency. So here is the "do or not do" of anti lock braking:

What to do: please put your foot on the brake pedal. Keep the brake pedal stable and constant pressure, and make the four-wheel ABS work normally. Even if the brake pedal is pulsating, avoid applying the brake. If you have a light truck with rear anti lock (rwal) brakes, brake the pedal with sufficient force to stop your truck without locking the front wheels. This allows you to maintain steering control and the rear anti lock system prevents the vehicle from skidding.

Please leave enough distance: when driving under good conditions, stay behind the vehicle for three seconds or more. If conditions are dangerous, please allow more time.

Practice driving with ABS: get used to the pulsation in the brake pedal when the anti lock brake is activated. Open parking or other open areas are great places to practice emergency parking.

Don't do it:

Do not drive vehicles with ABS more actively than vehicles without ABS. In any vehicle, it is risky to drive a curve faster, suddenly change lanes or perform other aggressive steering maneuvers.

With the four-wheel ABS system, the pumping brake turns the ABS on and off, reducing braking efficiency and increasing braking distance. ABS automatically provides you with brakes at a faster speed than your manual operation, and enables better steering control. More importantly, it can also brake on individual wheels as needed - something you can't do.

Car rubber parts remind you not to forget to turn. Four wheel ABS can help you avoid dangerous situations. When ABS is active, these conditions are normal and let you know whether the anti lock brake system is working normally. However, when braking normally on dry roads, there should be no ABS feedback. ABS should only function when panic stops or when the road is wet, cold, smooth or covered with loose gravel.

Related labels: automobile rubber parts, automobile rubber sleeve, automobile rubber pad