What are the braking principles
The working principle of braking is mainly from friction. By using the friction between the brake pad and the brake disc (drum) and between the tire and the ground, the kinetic energy of the vehicle will be converted into the heat energy after friction to stop the vehicle. A set of good and efficient braking system must be able to provide stable, sufficient and controllable braking force, and have good hydraulic transmission and heat dissipation capacity, to ensure that the force applied by the driver from the brake pedal can be fully and effectively transmitted to the master cylinder and each slave cylinder, and to avoid hydraulic failure and brake recession caused by high heat. The brake system on the car can be divided into two categories: disc brake and drum brake, but in addition to the cost advantage, the efficiency of drum brake is far less than that of disc brake.
friction
"Friction" refers to the motion resistance between the contact surfaces of two relatively moving objects. The magnitude of friction (F) is related to the friction coefficient（ μ） And the product of the normal pressure (N) in the vertical direction on the friction force bearing surface, expressed by the physical formula: F= μ N。 For the brake system:（ μ) Refers to the friction coefficient between the brake pad and the brake disc, and N is the force exerted by the brake caliper piston on the brake pad (Pedal Force). The greater the friction coefficient, the greater the friction force, but the friction coefficient between the brake pad and the disc will change due to the high heat generated after friction, that is, the friction coefficient（ μ） It changes with the change of temperature. Each brake pad has different friction coefficient change curve due to different materials. Therefore, different brake pads will have different optimal working temperature and applicable working temperature range. This is what you must know when purchasing brake pads.
Transmission of braking force
The force exerted by the brake caliper piston on the brake pad is called the brake pedal force. After the force of the driver stepping on the brake pedal is amplified by the lever of the pedal mechanism, the power boost uses the principle of vacuum pressure difference to amplify the force to push the brake master cylinder. The hydraulic pressure generated by the brake master cylinder uses the incompressible power transmission effect of the fluid, which is transmitted to each slave cylinder through the brake oil pipe, and uses the "Pascal principle" to amplify the pressure, pushing the piston of the slave cylinder to exert force on the brake pad. Pascal's Law means that the liquid pressure at any position in a closed container is the same.
The pressure is obtained by dividing the force application area by the force bearing area. When the pressure is equal, we can achieve the dynamic amplification effect by changing the ratio of the force application area to the force bearing area (P1=F1/A1=F2/A2=P2). In the brake system, the ratio of the master cylinder to the slave cylinder pressure is the ratio of the master cylinder piston area to the slave cylinder piston area.
Equipped with: ABS
ABS: Anti-lock Brake System, as the name implies, is "anti-lock brake system". Everyone knows that the maximum braking effect occurs at the moment before the tire locks. If the braking force can be kept in balance with the tire friction, the maximum braking effect will be achieved. When the braking force of the brake is greater than the friction of the tire, the tire will lock up. Once the tire locks up, the friction between the tire and the ground will change from "static friction" to "dynamic friction", not only the friction will be greatly reduced, but also the steering tracking ability will be lost. Because the tire locking is the result of the comparison between the braking force and the friction between the tire and the ground, that is to say, the limit of whether the tire is locked or not when the vehicle is moving will "vary at any time" according to the characteristics of the tire itself, the condition of the road surface, the positioning angle, the tire pressure, and the characteristics of the suspension system. ABS uses the speed sensor installed on four wheels to judge whether the tire is locked or not, eliminates the uncertainty of human body senses, and accurately controls and releases the hydraulic pressure of the brake wheel cylinder in time to prevent the brake from locking. At present, ABS is mostly designed to continuously step on and release 12~60 times per second (12~60Hz), which is an ultra-high level of performance compared to the top professional racing drivers' 3~6 times. The higher the frequency of step on and release, the more it can maintain the braking force at the edge of the limit. The accuracy and reliability that ABS can achieve has exceeded human limits, so we say that ABS is the most cost-effective equipment when buying a car. This is especially true for the relative danger of Air-Bag.
