What is the difference between front and rear brake pads? The two principles are different. Which one is used for emergency braking
The sudden braking in an emergency can save your life in some cases, which is not empty talk. The brake is one of the most important parts of a car. What is the difference between the front brake pad and the rear brake pad? When using, is it better to use the front brake pads or the rear brake pads?
The brake pad is the most critical safety component in the automobile braking system, and plays a decisive role in all braking effects. The brake pad is generally composed of steel plate, adhesive thermal insulation layer and friction block. The thermal insulation layer is composed of non thermal conductive materials, which plays the role of thermal insulation. The friction block is composed of friction materials and adhesives.
Squeeze the brake disc and brake drum to generate friction, so as to decelerate and brake the vehicle. The diameter of the brake drum of the drum brake will increase after heating, which will lead to the increase of the brake pedal travel, and it is easy to occur that the brake response is less than expected.
Therefore, when driving a vehicle with drum brake, try to avoid heat recession of brake pads caused by high temperature caused by continuous braking. The brake system responds slowly, and the pedal force of the brake is difficult to control, which is not conducive to high-frequency braking action. The brake clearance must be adjusted due to many parts and complex structure, which makes maintenance difficult.
The front wheels are usually a little larger than the rear brake pads. The rear wheels also have drum brakes. In fact, the wear rate of the brake pad is related to its service frequency and the force on the brake pad. The design of the vehicle fully considers the problems of brake inertia and forward impact. Therefore, when braking, the rear brake pad moves first, which is equivalent to pulling a car.
Delay for several milliseconds to avoid the feeling of forward rush. When braking at low speed and slow speed, the rear brake pads have been fully braked, so the front brake pads only take part in the movement for a short time to make the car stop completely. During high-speed emergency braking, the car is very likely to stand upside down (top up) under the effect of inertia, so the life of the front brake pad is more than half longer than that of the rear brake pad.
That is to say, nominally four brakes work at the same time, but in fact they do not. The rear brake is the service brake. Whether it is braking force or braking action time, the rear brake pad works. Under normal circumstances, the car is braked. When driving, the braking force of the four wheels increases synchronously, but the connection between the car body and the wheels is flexible.
When the car brakes, the wheels have been decelerating until they stop, and the car body is still in the forward state. Inertial action. The movement makes the center of gravity of the car move forward, which is called the brake mass transfer of the car. Under this effect, the load of the front wheel is far greater than that of the rear wheel when the car is braking, and the front wheel generally bears more than 70% of the braking force.
Therefore, the front brake pads will wear faster than the rear brake pads. So in order to adapt to this practical use. The front plate will be thicker than the rear plate. It is recommended to replace when 4mm is left. The thickness of the brake pads can be visually observed through the position of the vehicle. The wear rate of brake pads is mainly affected by their own materials and usage habits.
Some people have a good habit of driving, and wear and tear will be slow. In addition, the brake pads also have "alarm pads", that is, metal pads beside the brake pads. When the wear reaches a certain thickness, the alarm pad will directly contact the brake disc and make a sharp sound to remind the user to replace the brake pad However, because the alarm piece is generally arranged on one side, if the wear degree of both sides is inconsistent.
Early warning may not be possible. Therefore, it is recommended that the vehicle be checked every time it is repaired. Attenuation performance: Under downhill mountain road and other road conditions, the temperature will rise rapidly after continuous braking, and the brake disc temperature may reach 4, 500 or even 700 degrees Celsius. The braking capacity of the brake pads will deteriorate and the braking distance will increase. This phenomenon is called "recession".
We certainly hope that the smaller the recession rate, the better. The attenuation rate of high-quality brake pads is very small, and some even do not attenuate, while some fake and inferior products attenuate very seriously, and almost lose braking under high temperature. Restore the original braking performance? This is also the importance of measuring the brake pad quality.
In fact, the wear rate of the brake pad is related to its service frequency and the force on the brake pad. The design of the vehicle fully considers the problems of brake inertia and forward thrust, so the rear brake pads move first when braking. It is equivalent to pulling a car. The front brake pads lag for several milliseconds to avoid the feeling of rushing forward. At low speed and slow braking, the rear brake pads have been fully braked.