What is the principle of the ABS system?
4 Answers
The principle of the ABS system is: during braking, the ABS quickly determines the wheel lock-up state based on the speed signals from each wheel speed sensor, closes the normally open input solenoid valve on the wheel that is beginning to lock, and keeps the braking force constant. If the wheel continues to lock, the normally closed output solenoid valve is opened, and the braking pressure on that wheel rapidly decreases due to the direct connection to the brake fluid reservoir, preventing the wheel from completely locking due to excessive braking force. The functions of ABS are: 1. Maximize the effectiveness of the brakes, reducing braking time and distance; 2. Effectively prevent vehicle skidding and fishtailing during emergency braking, ensuring good driving stability; 3. Allow steering during emergency braking, providing good steering control; 4. Avoid severe friction between the tires and the ground, reducing tire wear.
I'm very interested in automotive technology. The ABS system, called the Anti-lock Braking System, works by electronically preventing wheel lock-up during emergency braking. There are speed sensors on the wheels that monitor wheel speed in real-time, and the data is transmitted to a computer unit called the ECU. When the ECU detects that a wheel is about to lock, it commands the hydraulic modulator to rapidly switch brake pressure—releasing and reapplying brake fluid dozens of times per second, effectively performing automatic cadence braking. This keeps the wheels slightly rotating, preventing skidding and loss of control, allowing you to steer around obstacles even while braking hard. ABS was first introduced in vehicles in the 1970s and is a fundamental active safety feature that significantly reduces braking distances on slippery surfaces. In daily driving, if you feel the brake pedal pulsating, that's the ABS working—no need to worry. The system requires regular maintenance, such as cleaning sensors or checking the hydraulic pump, otherwise, it may fail in winter, compromising handling safety.
As an ordinary person who drives frequently, I've used ABS several times in rainy and snowy weather, and it's really practical. The principle is that when you suddenly hit the brakes, the system detects that the wheels are about to stop, and the computer commands the brake hydraulic mechanism to quickly release and then reapply pressure, preventing the wheels from completely locking up. This allows you to brake while steering, such as avoiding potholes. When ABS activates, you can feel a slight vibration under your feet, but the car won't skid. Compared to older cars without ABS, which were prone to losing control, this system makes braking smoother and more reliable. The key point is that it helps reduce accidents, especially in rainy weather or on highways. I've found that ABS works best on icy and snowy roads, but it's important to note that severely worn tires can affect its performance. If an emergency arises while driving, ABS automatically activates, which is more effective and safer than manual pumping of the brakes.
When repairing cars, I often encounter ABS failures, with the most common issue being sensor malfunction due to dirt coverage. In principle, ABS relies on wheel speed sensors to capture data, which is then sent to the ECU for analysis. If a wheel's rotation speed drops abnormally and risks locking up, the ECU commands the hydraulic module to momentarily release and then reapply pressure, maintaining wheel rotation. This prevents skidding caused by complete lock-up and improves braking efficiency. Maintaining ABS is straightforward—I usually clean the sensors and wiring connectors and check the brake fluid level. If the ECU or hydraulic pump fails, professional repair may be needed at a moderate cost. When ABS is functioning normally, the brake pedal may slightly pulsate, but this shouldn't be mistaken for a fault. The system also prevents loss of directional control during braking on dry roads, making regular maintenance habits essential.
