Drum brake is worse than disc brake, why don't big trucks disc brake? You'll see!


In our daily driving, the brake is an important part of the vehicle, it is related to our driving safety. There are two brake systems, one is disc brake and the other is drum brake. These two braking systems basically cover most vehicles. As for their specific differences, I believe some car friends are more clear. Disc brakes are mainly used in common passenger cars, drum brakes are mainly used in large trucks and buses. So in the end is the disc brake or drum brake good?

The scientific name of the disc brake should be called disc brake. Usually, the main parts of disc brake are: brake pump, auxiliary pump, brake disc, brake pliers, brake disc, oil pipe and so on. When the vehicle needs to slow down, the brake tongs will grip the brake disc and use the friction between the disc and brake disc to slow down the vehicle, just like holding a piece of paper between two fingers. Generally speaking, cars will use this braking method.

Disc brake heat dissipation advantage is obvious. Most brake discs are made of steel because they dissipate heat very quickly and have a clear advantage during continuous braking, especially on downhill sections, where they retain sufficient braking force after repeated braking. In the same case, the drum brake will have serious braking force thermal attenuation, and will feel the brake is very weak, or even brake failure potential.

Drum brakes have been used in cars for nearly a century. In short, a drum brake is a brake that USES the static brake disc friction in the drum to rotate with the wheel to produce friction to reduce the wheel speed. When the brake pedal is pressed, the force exerted by the foot causes the piston in the master brake pump to push the brake oil forward, creating pressure in the oil path. The pressure is transferred to the brake pump piston of each wheel through the brake oil, and the piston of the brake pump pushes the brake disc outwards, causing friction between the brake disc and the inner surface of the brake drum, and generating enough friction to reduce the wheel speed, so as to achieve the purpose of braking.


1. Lower cost: drum brake is the first brake system with lower technical level, so its manufacturing cost is lower than that of disc brake.

2. The installation of hand brake mechanism is very easy. Some models with disc brakes on the rear wheels will have drum brakes in the center of the disc.

3. Drum brake has a good self-braking effect. The greater the external tension (braking force), the more obvious the situation. In addition to low cost, large and small car drum brakes can only be assisted by large pneumatic brakes, and small car drum brakes can be assisted by vacuum. That's why big trucks still use drum brakes.

Deficiency in

1. The diameter of the drum brake drum will increase when heated, which will increase the stroke of the brake pedal, and the brake reaction will be less than expected. Therefore, when driving with a drum brake, we should try our best to avoid the thermal deterioration of the brake disc due to the high temperature caused by continuous braking.

2. The response of the braking system is slow, and the braking force is difficult to control, which is not conducive to high-frequency braking.

3. There are many complex parts in the structure, and the brake clearance must be adjusted to make maintenance difficult.

As we all know, the biggest advantage of disc brake is its sensitivity, heat is also very good. The braking force is relatively uniform and beautiful. As a result, disc brakes were previously used only in premium cars. Nowadays, the cost of disc brakes is lower and lower, more and more disc brakes are used in household cars. Disc brakes are often used in household vehicles because they are usually light and require greater sensitivity than strength.

The biggest advantage of drum brake is its strong strength. For a truck, the weight of the car itself is much higher than the weight of a family car, plus the weight of the cargo being towed is very large. The essence of braking is "standing up", so if you want to stop a heavy truck, the braking force is much higher than the sensitive requirement, so large trucks use drum brakes.

However, since the truck's brakes are not sensitive enough, all domestic drivers should not rush to seize the road when they see the truck on the road, especially some dangerous overtaking behaviors, which may lead to rear-end collision. Although the back end of the truck is entirely its responsibility, how can the small body of a domestic car withstand such a big truck collision, and then it may be damaged not only our car.

However, the biggest disadvantage of drum brakes is that they have heat dissipation problems, and easy to heat failure, which is the drum brakes gradually out of the field of household cars. Even in the truck, on the highway there are often accidents like car tire fire, is due to the brake is too tired, due to the heat is too high, but the strength of the drum brake is still so that it can not be replaced in the truck.