We all know that in today’s family cars, the braking methods used are nothing more than disc brakes (disc brakes) and drum brakes (drum brakes). In the eyes of most people, disc brakes represent Advanced, Gusha represents backwardness, but is this really the case in internship? Let’s clarify them one by one.

Disc brake (disc brake)

1.Components

Usually the main components of disc brakes are: brake master cylinder, wheel cylinder, brake disc, brake caliper, brake pad, oil pipe, etc.

2. Braking principle

The braking principle of disc brake is very simple and well explained. When the vehicle needs to decelerate, the brake caliper will clamp the brake disc, and the vehicle will decelerate through the friction between the brake pad and the brake disc, just like you It's the same as holding a piece of paper with two fingers. The brake calipers are pushed by brake pistons, which are powered by hydraulic pressure. During the braking process, the original mechanical energy of the vehicle is converted into thermal energy and then lost in the air.

3.Advantages

Because the brake disc of the disc brake is exposed to the air, the brake disc is directly air-cooled during driving, which can cool down relatively quickly and prevent the brakes from quickly experiencing thermal decay. Moreover, the force with which the piston pushes the brake caliper to clamp the brake disc is linearly related to the driver's force on the brake, so the driver can control the braking force more easily.

4. Defects

As long as the car uses disc brakes, it needs to be equipped with a power assist system for the brakes, because the driver's foot alone cannot achieve the required braking force. Most vehicle power assist systems rely on vacuum brake booster pumps. The vacuum force generally comes from the negative pressure generated in the engine's intake manifold. This also explains why there is only one opportunity to "brake" after parking and turning off the engine, because there is no power assist when the second brake is applied, and the brake pedal is as hard as a stone.

Drum brake (drum brake)

1. Composition

A typical drum brake mainly consists of base plate, brake drum, brake shoe, wheel cylinder (brake wheel cylinder), return spring, positioning pin and other components.

2. Braking principle

The brake drum is installed on the wheel hub and is a component that rotates with the wheel. It is made of a certain amount of cast iron and is shaped like a drum. When braking, the wheel cylinder piston pushes against the brake drum (inside), and the brake drum is decelerated by friction, forcing the wheel to stop rolling.

Of course, the processing and composition of drum brake parts are relatively simple, which can greatly reduce the manufacturing cost. This is why we believe that drum brakes are the factors of simple assembly and poor knowledge.

3. Disadvantages

A nearly closed brake drum, so the heat dissipation ability of drum brakes is much worse than that of disc brakes. The diameter of the brake drum will increase after being heated, which will cause the stroke of the brake pedal to be increased, and it is easy to cause brake heat attenuation Phenomenon.

Because drum brakes have another advantage over disc brakes that does not seem to be an advantage - the return spring. Due to the existence of the drum brake return spring, when the brake is not needed (release the brake), the brake shoe and the brake The drum can be separated in an instant, without wasting any rated power. However, the disc brake pad and the brake disc cannot be separated so quickly. This waste of energy is very small, but it means a pure electric vehicle with a small capacity battery. To be able to run further.