Introduction
Wondering How ABS Works? An anti-lock braking system (ABS) is a safety feature in automobiles like cars that helps in maintaining tire grip while braking. It prevents wheels from locking up and assists drivers in maintaining steering control and avoiding sliding during braking. ABS allows vehicle wheels to keep tractive contact with the ground, preventing an uncontrollable skid. You have more control over your car with ABS in circumstances like rapid braking.
If your vehicle doesn’t have ABS, and you apply a sudden brake, the wheels lock up and the tires lose grip and the vehicle starts sliding. No matter how hard you try to steer, your vehicle will continue sliding.
Want to know how ABS works? Let’s dive in!
How does ABS work?
To get a full understanding of how do anti-lock brakes work, we need to understand the basic mechanism.
The signal from each of the wheel’s speed sensors is read by the ECU. When a driver suddenly uses the brakes, the wheel decelerates at a faster rate, which can cause the wheel to lock. The ECU receives the signal indicating a sudden decrease in wheel speed and sends it to the valve. This makes the valve close and reduces the pressure on the brake pad, preventing the wheel from locking.
The wheel accelerates again, and the signal is sent to the controller. This time it opens the valve, raises the pressure on the brake pad and applies the brakes. It reduces the wheel’s speed again and attempts to stop.
When a driver abruptly applies the brakes harder, the process of applying and releasing them occurs 15 times in a second. As a result, the locking of the wheel is prevented, and the vehicle’s skidding is eliminated. The driver can maneuver the car while braking with the ABS, reducing the danger of an accident.
To understand the detailed working of ABS, it’s important to go through the functions of ABS and its components.
Components of ABS
The ABS adjusts the brake line pressure of the vehicle independent of the pedal force. This brings the speed of the wheel back to the slip level required for optimal braking performance. It prohibits full-wheel lock under braking and results in steering control. It works based on its four main components.
1. Speed Sensors
Each of the ABS wheel speed sensors monitors the speed and determines the required deceleration or acceleration of the corresponding wheel. It is made up of a permanent magnet, coil, and ring with V-shaped teeth known as a tone wheel. The magnetic flux generated by the permanent magnet changes when each tooth of the tone wheel passes in front of it. Voltages are induced by the changing magnetic flux at a frequency that corresponds to the wheel speed. The controller receives signals from the voltage generated and reads the acceleration and deceleration of the wheel.
2. Master Cylinder and Valves
Master cylinder is a device that is used to pump brake fluid and is made up of three parts: a piston, brake fluid, and a return spring. As the piston rod is attached to the brake pedal, when the driver presses the brake pedal, the brake fluid inside the master cylinder is pressed by the piston. The master cylinder is connected to the oil reservoir, which controls the amount of oil in the system.
There is a valve on each brake line that is regulated by the ABS. The valve can be set to three different positions in some systems.
- The valve remains open in position one, allowing pressure from the master cylinder to pass through to the brake.
- It blocks the line and separates the brake from the master cylinder in position two. As a result, the brake pressure does not rise any further. When the driver uses the brakes more forcefully, the valve moves to the second position.
- The valve releases some of the pressure from the brake in position three. This step is repeated till the car stops. The brake valves govern the pressure that is delivered from the master cylinder to the brakes. As a result, you feel resistance while braking suddenly at high speeds.
The valve clogging is the most serious issue with ABS. The valve becomes difficult to open, close, or change position as it becomes clogged. When the valve is inoperable, the system is unable to modulate the valves and control the pressure to the brakes.
3. Electronic Control Unit
The ECU’s job is to receive, amplify, and filter sensor signals to calculate the vehicle’s speed, rotation, and acceleration. The ECU also estimates the vehicle’s speed based on the speeds of two diagonally opposing wheels. By comparing the reference speed to the individual wheel, the slip of each wheel is calculated. The signal server warns the ECU in the event of wheel slide or wheel acceleration. The controller limits the brake force (EBD) and activates the ABS modulator.
The activated ABS modulator turns on and off the braking valves and changes the brake pressure. The pressure control valve of the solenoids of the pressure modulator is triggered by the microprocessor, which modulates the braking pressure in the individual wheel brake cylinders. When the ECU detects a fault or problem, it shuts down the ABS or switches off the malfunctioning element of the system.
4. Hydraulic Control Unit
Hydraulic Control Unit applies or releases the brake, based on signals received from the Electronic Control Unit (ECU) to prevent the wheel from locking up while braking. It is an electro-hydraulic device that manipulates the solenoid valve in the hydraulic braking system to reduce, restore, and retain the wheel pressure. It controls the holding and release of the various hydraulic brake circuits during heavy braking.
The basic braking system is utilized in normal conditions. When a hard braking scenario occurs, the system detects a change in the rotation of the speed sensor and determines whether to maintain or release brake pressure. A tire’s best traction is just before it starts to skid; once it starts to skid, grip and steering are lost.
It consists of the following elements:
Pump
The master cylinder is connected to the pump’s inlet while the accumulator is connected to its outlet. The master cylinder sends brake fluid to the accumulator, which is then pressurized by the pump.
Accumulator
This is a storage device that holds the pressurized brake fluid. The accumulator’s outlet is connected to the solenoid valves.
Solenoid Valves
Solenoid valves respond to signals from the ECU to pressurize the brake fluid and apply the brakes. Then it turns off the brake fluid supply and at last restarts the brake fluid flow to release the brake force on the wheel.
Types of ABS
The antilock brake is categorized based on the number of valves, channels, and speed sensors.
1. Four-Channel, Four Sensor ABS
It is a more preferred type, as it has a speed sensor on each of the four wheels and a separate valve for each wheel. With this combination, the controller analyses each tire individually to ensure it is achieving maximum braking force.
2. Three-Channel, Three Sensor ABS
This type is typically seen on pickup trucks with four-wheel ABS. It features one valve and a one-speed sensor for each of the front wheels, and one valve and one sensor for both rear wheels. The rear-wheel speed sensor is positioned in the back axle.
This design gives each of the front wheels independent control, allowing them to produce maximum braking force. The rear wheels, on the other hand, are monitored in tandem and they must both begin to lock up before the ABS on the back activates. It’s possible that one of the rear wheels can lock at a stop with this design and reduce brake efficacy.
3. One-Channel, One-Sensor ABS
This type is most typically found on heavy trucks equipped with rear-wheel anti-lock brakes. It has a one-speed sensor in the rear axle and one valve that controls both rear wheels. It works in the same way as a three-channel system’s back end.
The rear wheels are monitored in tandem, and they must both begin to lock up before the ABS activates. It’s also possible that one of the rear wheels will lock in this setup, lowering brake efficacy.
This type of ABS is simple to recognize. One brake line is usually connected to both rear wheels through a T-fitting. By looking for an electrical connection near the differential on the rear axle housing you can find the speed sensor.
Conclusion
The braking system in automobiles is becoming increasingly complex as technology advances. Anti Lock brakes assist drivers in maintaining vehicle control in situations where heavy braking is required. Drivers in vehicles without anti-lock braking systems must pump their brakes to avoid spinning out of control due to locked-up wheels. The antilock braking system uses a sensor on each wheel to coordinate wheel activity and adjust brake pressure as needed, ensuring that all wheels are operating at the same pace.
So this was how ABS works. If you want complete detail on winter driving safety tips, then Click Here! and subscribe to Suzuki Fort Motors Newsletter to get the latest updates about Suzuki Vehicle Prices and Parts Updates.
