Most light vehicles use hydraulic braking, and hydraulic pressure needs to use pipelines. Double-loop braking system means that there are two independent hydraulic braking pipeline systems in the system, which play the role of insurance. Generally, front-wheel drive vehicles mostly adopt the cross diagonal form. The front cavity of the brake master cylinder is communicated with the brake pipes of the right front wheel and the left rear wheel, and the rear cavity is communicated with the brake pipes of the left front wheel and the right rear wheel to form a cross-shaped X diagonal. Its advantage is that when one braking system fails, the other system can still perform minimum braking, and the car is not easy to run off. Because of the heavy load, rear-wheel drive vehicles mostly adopt the form of independent braking of front and rear wheels, that is, there are two sets of brake master cylinders, one for controlling front-wheel braking and the other for controlling rear-wheel braking.

Disc brake:

Disc brake, also known as disc brake, is named after its shape. It is controlled by hydraulic pressure, and its main components are brake disc, brake cylinder, brake caliper and oil pipe. The brake disc is made of alloy steel, fixed on the axle and rotates with the wheel. The driven pump is fixed on the brake base plate. The two friction plates on the brake caliper are installed on both sides of the brake disc respectively. The piston of the slave cylinder is influenced by the hydraulic pressure delivered by the oil pipe, which pushes the friction plate to press the brake disc for friction braking. This brake has the advantages of fast heat dissipation, light weight, simple structure and convenient adjustment. Especially under high load, it has good high temperature resistance, stable braking effect and is not afraid of mud invasion. Some disc brakes also have many small holes in the brake disc to speed up ventilation and heat dissipation and improve braking efficiency. This kind of disc brake is also called ventilated disc brake. Because of its high manufacturing cost, it is generally only used for the front wheels of four-disc brakes.

Of course, the disc brake also has its own defects. For example, the manufacturing requirements of brakes and brake pipes are higher, the cost of friction plates is higher, the friction plate area is small, and the friction working surface is relatively small, so the braking hydraulic pressure is required to be high, and vehicles with power-assisted devices are required to use it.

At present, most middle and high-class cars use four-wheel disc brakes, and in the whole automobile field, disc brakes have a tendency to gradually replace drum brakes.

Drum brake:

Drum brake is the earliest form of automobile brake. Before disc brakes appeared, they were widely used in various automobiles. However, due to structural problems, in the past 30 years, it has gradually given way to disc brakes in the field of cars. However, due to its low cost, it is still used in some economical cars, mainly for rear wheel braking and parking braking with less load.

Automobile drum brakes are generally used for rear wheels (disc brakes are used for front wheels). Besides the low cost, the drum brake has another advantage, that is, it is easy to be combined with the parking brake. For cars with drum brakes on the rear wheels, the parking brake is also used in combination with the rear wheel brake. This is a mechanical system, which is completely separated from the braking hydraulic system on the car: the steel cable is tightened by the hand lever or parking pedal (American car), and the brake shoe is expanded by manipulating the lever of the drum brake to play the role of parking braking, so that the car will not slip; Loosen the steel cable, return the spring to restore the brake shoe to its original position, and the braking force disappears.

ABS system:

"Anti-lock braking system" Anti-lock braking system, referred to as ABS.

ABS provides a favorable guarantee for driving safety. ABS is an improved technology based on the traditional braking device. Its working principle is that it is controlled by computer through the high-sensitivity wheel speed sensor installed on each wheel and the speed sensor on the car body. During emergency braking, once the wheel is locked, the computer immediately instructs the pressure regulator to release (reduce) the pressure of the wheel brake cylinder to make the wheel rotate again. The working process of ABS is actually a locking-releasing-locking-releasing cyclic working process, which keeps the vehicle rolling in the critical locking gap all the time, effectively overcomes the deviation, side slip and tail flick during emergency braking, and prevents the occurrence of out-of-control situations. The national standard GB 13594 clearly stipulates that ABS belongs to electromechanical integration parts, which are composed of the following components: one or several sensors; One or more controllers and one or more regulators.

ABS system doesn't work every time braking is taken, but only when the wheels are close to locking. It doesn't work quietly. If ABS works while stepping on the brake pedal, it will produce appropriate noise, and the brake pedal will repeatedly pulse and arch. This is a normal phenomenon that ABS system automatically adjusts the brake oil pressure. It is correct to always step on the brake pedal with your foot when braking.

The ABS system has very high requirements for brake fluid, so the brake fluid must be added in strict accordance with the requirements in the instruction manual, and it is forbidden to mix different types of brake fluid. Generally speaking, the same type of brake fluid should be replaced once a year. You can also choose DOT3 or DOT4 alcohol-based brake fluid.

Vehicles equipped with ABS system should strictly abide by the specified tire pressure standards, and maintain the coaxial tire pressure balance. It is strictly forbidden to use tires with different specifications. Answer supplement

EBD:

The English full name is Electric Brakeforce Distribution, and the Chinese literal translation is "electronic braking force distribution". When braking a car, if the four tires touch the ground differently and the friction between the four wheels and the ground is different, it is easy to slip, tilt and roll over when braking. The function of EBD is to calculate the friction values of four tires with different adhesion at high speed at the moment of braking, and then adjust the braking device so that it can be adjusted at high speed according to the set program during movement, so as to achieve the matching of braking force and friction (traction) and ensure the stability and safety of the vehicle.

EBD can be said to be an auxiliary function of ABS in essence, which can improve the efficacy of ABS. Therefore, in terms of safety indicators, the performance of the car is better. When braking again, EBD will automatically compare the slip ratio of the rear wheel and the front wheel according to the vehicle weight and the road conditions before ABS action. If it is found that this difference must be adjusted, the brake oil pressure system will adjust the oil pressure transmitted to the rear wheel to obtain a more balanced and idealized braking force distribution. Therefore, EBD+ABS is based on ABS to balance the effective grip of each wheel, improve the balance of braking force, prevent tail flick and side slip, and shorten the braking distance of the car. The answer complements sabs:

Now some pickup truck manufacturers recommend SABS (SABS) as anti-lock braking system (ABS), which is also called mechanical ABS. This is misleading to consumers. Sabs is not abs, nor can it replace ABS.

Sabs uses the change of the distance (external force) between the car body and the axle to change the pre-tightening force of the spring, and makes corresponding adjustments with the increase of vehicle load, so that an approximate ideal braking force distribution can be obtained under any load condition. It is installed on the pipeline between the master brake cylinder and the rear wheel brake cylinder, and consists of a shell, a plunger, a valve, a spring, etc. The oil inlet hole of the shell is communicated with the oil outlet hole of the master brake cylinder, and the oil outlet hole is communicated with the wheel brake cylinder. When the external force is small, the plunger of sabs is pushed to the extreme right under the pre-tightening force of the spring, the two holes are connected, and the pressure of the master cylinder and the slave cylinder is equal. When the external force is greater than the pre-tightening force of the spring, the plunger is forced to move to the left, so that the plunger contacts the valve and closes the valve, cutting off the passage from the master cylinder to the sub-cylinder; If the external pressure continues to increase, the plunger will move to the right, the plunger will be out of contact with the valve, the valve will be opened again, and the master cylinder and the slave cylinder will be connected again. In this way, the repeated action of the proportional valve makes the hydraulic pressure of the cylinder continuously adjusted, that is, the braking force of the rear wheel continuously adjusted.

SABS (SABS) has no influence on the empty or snowy road surface, and only on the fully loaded or dry road surface can sideslip be avoided.