What is a car brake and what does it feel like?

There are more and more ABS (anti-lock braking systems) on cars now, and some manufacturers even use ABS to "make excuses", as if cars with ABS are superior to others, and some simply The three letters ABS are stuck on the butt of the car to show itself. 1. What is "brake lock"? 2. Do cars have to have ABS? Isn't it just fine if the original car doesn't have ABS? Why does it have to be equipped with ABS? 3. Are there different grades of ABS? What kind of ABS is best? 4. Can ABS really shorten braking distance?

In fact, ABS is a commonplace issue, but since it is related to safety, it is better to know more about it. ABS is the abbreviation of English Anti-lock Braking

System. Since ABS was introduced from aircraft to cars, it can be said to be very popular, and many high-end cars have long included it as standard equipment. Now, equipped with ABS is no longer exclusive to high-end cars.

1. When the tire cannot rotate due to braking and loses friction with the ground, it can be said that the tire has been "locked" by the brake pads. If the front wheels are locked, at this time, any function of controlling the direction of the car is almost zero, so there is no corresponding relationship between the rotation of the steering wheel and the direction of the car, and the direction of the car cannot be controlled; if the rear wheels are ahead of the front When the wheels are locked, the ability of the rear wheels to control the rear of the car disappears immediately. At this time, the force preventing the wheels from moving forward is concentrated on the front wheels, and the rear of the car will twist uncontrollably, which is often called "drifting". It's quite dangerous at this time.

2. Applying the brakes while the vehicle is driving, especially when braking suddenly, can easily cause the tires to lock up and cause the vehicle to slip. The vehicle body can easily slide sideways, swing its head, or drift. At this time, it is impossible to control the steering wheel. The direction of the car changes, and the rolling friction between the tire and the ground changes to sliding friction, and the grip almost disappears. At this time, the ABS senses that the tire is locked and will quickly "click and release" the brake pads. This can relieve the tire locking phenomenon and maintain the adhesion between the tire and the ground, so the driver can control the direction of the vehicle body.

A real driving expert without ABS can still achieve the goal of preventing brake locking by "point braking", but after all, these people are only a minority. Moreover, if the grip of the four wheels is different, high-end ABS can adjust the braking force on each wheel separately according to the grip of each wheel, which is something that no good driver can do.

3. Of course, ABS has different grades. ABS is divided into two types: electronic and mechanical. Usually the ABS equipped with the original car is electronic, while the ABS installed after purchasing the car is mostly mechanical. Generally speaking, mechanical ABS is not as effective as electronic ABS.

Electronic ABS is divided into three types according to the number of hydraulic circuits: one is single-circuit ABS. This kind of ABS only controls the rear wheels, is mostly installed on trucks, and is only equipped with one wheel speed sensor, usually installed in the rear axle differential. The most commonly used ABS in cars is a three-circuit system. The two front wheels are each controlled by a set of oil circuits. Because the center of gravity moves forward during braking, most of the braking force occurs on the front wheels, and the load on the rear wheels is quite light, so only one set of oil circuits is used to control the two rear wheels. Each wheel of four-circuit ABS is responsible for an independent oil circuit. Generally, four-circuit ABS is installed on high-performance cars.

4. ABS can shorten the braking distance, but the effect is still limited. ABS cannot significantly shorten the braking distance. On a normal straight road, a skilled driver can often stop faster without ABS than with ABS. The main task of ABS is to prevent the tires from locking up and causing the vehicle body to lose control and cause dangerous phenomena such as sideslip and drift. Therefore, when the brake disc is under excessive pressure and is about to lock, the ABS will sense it on its own and adopt appropriate intermittent retraction and release of the brake pressure. Before the tire locks (that is, before rolling changes to sliding), the friction with the ground can reaches the maximum value, which means the best deceleration force and the shortest braking distance. Therefore, strictly speaking, the shortened braking distance is only an added value of ABS, so the effect is not obvious.

The original intention of ABS is to prevent dangerous phenomena such as side slipping and drifting of the car.