What are the characteristics of disc brakes and drum brakes?

Author: sungooking

Link: https://www.zhihu.com/question/468608940/answer/1970554333

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Braking effect: drum ＞disc This is determined by the structure, drum brakes braking force is definitely greater than disc production cost: disc ＞drum So why are discs used now? Because of safety. Drum brakes are extremely poor in heat dissipation due to the internal closure of the brake structure. Brakes are very easy to produce high temperatures. Two feet of heavy brakes can reach more than two hundred degrees Celsius. But more than the operating temperature brake friction will show a precipitous drop. Cliff type is equivalent to instant no friction, no brake. So drum brakes have been gradually eliminated by disc brakes in the field of family cars. Large lorries now generally use drum brakes, because they can provide stronger braking force. What about poor heat dissipation? It's down to the experienced skill of the driver. So we often see trucks in the brake failure, in the highway long distance downhill on the right side of the emergency lane, is for those trucks with brake failure using disc brakes, although the structure of the braking force is not as strong as the drum brakes, but the heat dissipation performance is particularly good. It is also possible to make the heat dissipation performance better by means of air-conducting brake discs and so on. The lack of braking power has been made up for in other ways, such as through materials. The braking power of the disc brakes is also sufficiently adequate for a car that doesn't weigh much. Stability is also an important factor for small cars with varying levels of driving. Otherwise, if the brakes fail at any time, there will be accidents and incidents on the road every day. For high-intensity use of brakes for motor sports, moving several hundred degrees of brake temperature, heat dissipation is certainly more important.