Some time ago, a Mercedes Benz car came to the maintenance shop. At present, the car has driven more than 85000 kilometers. The owner described the fault to the repairman. Now his car can always hear squeaking noises when driving or stepping on the brake, and the brake fault light is on and does not go out.

其實，這輛奔馳車在上次做保養的時候，修車師傅就檢查到該車的剎車片該換了，可能當時車主確實有事，也或許是不太相信修車師傅所說的話，反正當時給推辭了沒有更換，這不跑了還不到1千公里就出現了問題。

In fact, when the Mercedes Benz was serviced last time, the repairman checked that the brake pads of the car should be replaced. Maybe the owner was really busy at that time, or maybe he didn't believe what the repairman said. Anyway, he refused at that time and didn't replace it. After not running for less than 1000 kilometers, there was a problem.

由于修車師傅已經知道哪里出了問題，所以接過車后就直接就把剎車片拆了下來，從下圖中可以看到，剎車片上的報警線已經被磨損去了一大半，這就證明剎車該換了。

Since the repairman already knew what was wrong, he directly removed the brake pad after receiving the car. As can be seen from the figure below, more than half of the alarm line on the brake pad has been worn, which proves that the brake should be replaced.

奔馳車主看到剎車片磨成這般模樣，毫不猶豫同意修車師傅更換掉，下圖這是修車師傅讓車主觀看新舊剎車片的對比，左邊的新剎車片明顯要比右邊的舊剎車片要厚很多。

The owner of Mercedes Benz saw that the brake pads were ground like this and did not hesitate to agree to the repairman to replace them. In the figure below, the repairman asked the owner to see the comparison between the old and new brake pads. The new brake pad on the left is obviously much thicker than the old brake pad on the right.

不過修車師傅在拆卸剎車片的過程中，還發現因剎車片沒有及時更換，還導致了剎車盤受到了一定的磨損，剎車盤的邊緣凸起了很多，修車師傅表示，這一情況是需要處理的，不然安裝上新剎車片后就會出現異響的問題。如下圖所示；

However, in the process of removing the brake pads, the repairman also found that the brake pads were not replaced in time, which also led to certain wear on the brake discs, and the edges of the brake discs bulged a lot. The repairman said that this situation needs to be handled, otherwise there will be a problem of abnormal noise after installing new brake pads. As shown in the figure below;

奔馳車主得知這一問題后，趕緊問修車師傅這該怎么處理呢？只見修車師傅把剎車盤拆卸下來，之后固定在一個機器上便開始打磨了起來。修車師傅這樣的維修辦法，讓車主很擔憂，本來剎車盤的厚度就很薄了，這經過這么一打磨豈不是更不安全了嗎？

When Mercedes Benz owners learned of this problem, they quickly asked the repairman how to deal with it? The mechanic took down the brake disc, fixed it on a machine and began to polish it. The maintenance method of the car repairman worries the car owner. The thickness of the brake disc is very thin. Isn't it safer after such polishing?

修車師傅得知奔馳車主的擔憂后，向車主解釋到，這是在鏜盤，只是將剎車盤邊緣凸起的部位鏜掉，而并非是在對剎車盤厚度打磨，更不會影響到安全問題，奔馳車主聽到修車師傅的解釋后，這才把心放了下來。

After learning about the concerns of Mercedes Benz owners, the repairman explained to the owners that this was boring the disc, only boring the convex parts at the edge of the brake disc, not grinding the thickness of the brake disc, and it would not affect the safety problem. Mercedes Benz owners relieved themselves after hearing the explanation of the repairman.