Why are the brakes of trucks drum brakes while most cars disc brakes? In the field of family cars, the vast majority of models use disc brakes, at least a few low-end models still use drum brakes. Of course, some models like Volkswagen id.4 and Nissan Tuda also use drum brakes, which is not very appropriate.

Old drivers all know that it's more important to brake well than to run fast. Drum brake and disc brake have their own advantages, but in the field of family cars, drum brake is definitely a more suitable choice.

Structural differences between drum brake and disc brake

First of all, let's talk about the difference between drum brake and disc brake. In terms of structure, drum brake and disc brake are quite different.

The disc brake uses the brake disc to brake, that is, through the hydraulic device, to push the friction plate and the wheel brake drum for friction, through the friction to brake. The following picture shows the characteristics of the two kinds of brakes very intuitively. The drum brake is to open the brake shoes and rub the inside of the brake drum. This kind of braking method is relatively simple and rough. The disc brake rubs against the brake drum by compressing the friction plate.

Advantages and disadvantages of drum brake and disc brake

Drum brake is a relatively simple and rough braking mode, with relatively simple structure and lower cost. Because the contact area with the brake drum is larger, the braking force is stronger. But the disadvantages are also very obvious. First of all, the heat dissipation effect is relatively poor, because its brake shoes are inside. After many times of sudden braking, there will be very obvious heat attenuation, and even brake failure. Some cars will catch fire due to overheated brakes. In addition, the drum brake needs a closed structure, once wading, dust, foreign matter will affect the brake. Finally, the braking force of the drum brake is not linear. Compared with the friction braking of the disc brake, the drum brake is difficult to achieve smooth braking.

The structure of the disc brake is relatively more complex. Its advantages are that the braking force is relatively linear, and the heat dissipation effect is better. The thermal attenuation of the continuous brake is relatively not obvious, but there are also some disadvantages, that is, the absolute braking force is not so strong, and the brake pads often need to be replaced

After looking at the advantages and disadvantages of drum brake and disc brake, we can see why trucks tend to choose drum brake, while household cars tend to choose disc brake. The biggest problem of drum brake is that the thermal attenuation and braking force are not linear enough, so it is not suitable for the brake system of household cars. Of course, it can not be ruled out that some car companies can adjust the drum brake better and more linear, but in terms of structure, the disc brake is definitely more suitable for household cars than the drum brake. As for those who choose to use drum brake as the brake mechanism of household car, I can't think of any other reason besides saving cost.