If you step on it for a long time, it may not work. What is the brake attenuation？

We have to drive every day, and the accelerator and these two things are used many times every day. We also know that a car of more than one ton was stopped by friction. From the day we picked up the car, there was a view that it would decay and even lose its strength. Then we can’t help but ask: will it decay? Why does it decay?

Brakes really attenuate.

Attenuation does occur. This phenomenon is called, which means that the disk (or drum) produces high temperature for a long time, which leads to the decrease of force and finally disappears completely. Generally, it appears after heavy load stepping on a long slope or after a long period of intense driving. In the end, it will really lead to the complete disappearance of force, which will have very terrible consequences. But, why is this happening?

First, review the principle.

Before we start, let’s review the working principle of. Here, take the dish type as an example. The drum type is slightly different, but the principle is similar. Brake, which is made of special material, directly rubs against the roughened steel plate to slow down the speed. Friction will produce energy. According to the law of conservation of energy, when the rotation speed of the disk is reduced by friction, energy will inevitably be converted into heat and accumulated on the disk, so it will generate heat. This is the truth.

Why does it decay?

After a brief introduction of the principle, we will analyze why it decays. As mentioned earlier, it will be hot. Because the disk is rotating and there are rims outside, under normal circumstances, the heat generated will be taken away by the re-accelerated rims soon, and the heat generated by itself is not enough to have any impact, so it basically has no impact on performance.

But it will be different for a long time. Whether it is heavy load for a long time or continuous heavy braking. These actions will generate a lot of heat, which can’t be dissipated at all, but can only be accumulated continuously, so that the temperature of the whole plate will be higher and higher. When it reaches a certain level, a physical phenomenon will appear.

From the microscopic point of view, temperature is actually the result of molecular movement. In physics, the higher the temperature, the greater the attraction and repulsion between molecules. The disk itself is made of steel. After the temperature rises sharply, the molecules in the steel structure will generate great attraction and repulsion, which will make the surface of the steel structure expand and tend to be flat. In other words, the rough surface machined on the disk will become smooth at high temperature. When the same force is applied to the disk, the friction against the disk will be reduced. At the same time, because the intermolecular fusion force between the two (the same phenomenon will occur) becomes low, it can not produce enough friction on the disk. Under the combination of the two, the final effect is a sharp drop in force.

How to solve it?

In view of this problem, the mainstream solution is to draw several lines on the disk to help dissipate heat and make the disk useful at high temperature. In addition to scribing, there is another way to drill holes in the disc. These two ways are mainly to increase the heat dissipation of the large market and delay the occurrence time of attenuation, which is what the general family car does at most.

For some higher-performance vehicles, they will add some special materials to the disk, or switch to a larger size disk, which can effectively delay the emergence of the opportunity. Of course, some high-performance cars or super cars, which often go up to 600, will directly use ceramic materials with high density structure, and infiltrate carbon into them to make carbon ceramic disks. Or that disk is made of special metal. At this point, it’s basically the best that civilian cars can do. If you want to completely eliminate it, you can only refer to the Zentraedi technology materials used in high-level racing cars, which are calculated at tens of thousands or even hundreds of thousands of dollars.

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