[Catalog:News] [Date:2022-9-14] [Hits:] [Return]

A car can only run on the road because of the rotation of its wheels. What should we do when the car is about to stop? It is impossible for the driver to put his foot on the ground to stop the car from moving forward as in the cartoon. At this time, he must rely on the brake device on the car to slow down and stop the car.

Brake: As the name implies, it is a mechanical brake device that can slow down the speed, also known as a reducer. To put it simply: the brake pedal of an automobile is under the steering wheel. If you step on the brake pedal, the brake lever linkage will be pressed and the brake pads sent to the brake drum will jam the brake disc, causing the automobile to slow down or stop running. The manual brake of the car is next to the gear and connected to the brake lever. The bicycle brake is also commonly used. It decelerates by the rod brake fixed on the frame or disc mounted holding brake.

The braking system hidden in the wheel is an important device to stop a moving car. The braking device generates friction between the brake pad and the wheel drum or disc, and in the process of friction, it converts the kinetic energy of the car into heat energy for consumption. The common brake devices are "drum brake" and "disc brake". Their basic features are as follows:

1、 Drum brake:

Two semicircular brake pads are installed in the wheel hub, and the brake pads are pushed by the "lever principle" to make the brake pads contact with the inner surface of the wheel drum and cause friction.

The drum brake has been used in automobiles for nearly a century. However, due to its reliability and powerful braking force, the drum brake is still used in many models (mostly in the rear wheels). Drum brake is to push the brake pad installed in the brake drum outward by hydraulic pressure, so that the brake pad will rub with the inner surface of the brake drum rotating with the wheel, thus producing the braking effect.

The inner surface of the brake drum of the drum brake is the position where the brake device generates the braking torque. Under the condition of obtaining the same braking torque, the diameter of the brake drum of the drum brake device can be much smaller than that of the brake disc of the disc brake. Therefore, in order to obtain strong braking force, large vehicles with heavy loads can only install drum brakes in the limited space of the rims.

Operation mode of drum brake

To put it simply, drum brake is a brake device that uses the static brake pads in the brake drum to friction the brake drum that rotates with the wheel, so as to generate friction to reduce the wheel rotation speed.

When the brake pedal is depressed, the force exerted by the foot will make the piston in the brake master cylinder push the brake oil forward and generate pressure in the oil circuit. The pressure is transmitted to the piston of the brake wheel cylinder of each wheel through the brake oil, and the piston of the brake wheel cylinder pushes the brake pad outward, causing friction between the brake pad and the inner surface of the brake drum, and generating enough friction to reduce the speed of the wheel, so as to achieve the purpose of braking.

Advantages of drum brake

1. It is used for automatic brake, so that the brake system can use lower oil pressure, or use a brake drum whose diameter is much smaller than the brake disc.

2. Handbrake mechanism is easy to install. Some models with disc brakes on the rear wheels will be equipped with drum brake handbrake mechanism at the center of the brake disc.

3. The processing and composition of parts are relatively simple, and the manufacturing cost is relatively low.

Disadvantages of drum brake:

1. The diameter of the brake drum of drum brake will increase after being heated, which will result in an increase in the stroke of stepping on the brake pedal, and it is easy to happen that the brake response is not as expected. Therefore, when driving a vehicle with drum brake, try to avoid the thermal recession of brake pads caused by high temperature due to continuous braking.

2. The brake system responds slowly, and the pedal force of the brake is difficult to control, which is not conducive to high-frequency braking action.

3. There are many parts with complex structure, and the brake clearance must be adjusted, making maintenance difficult.

Due to the rapid increase of vehicle performance and driving speed, the disc brake has become the mainstream of the current brake system in order to increase the braking stability of vehicles at high speeds. As the brake disc of the disc brake is exposed to the air, the disc brake has excellent heat dissipation. When the vehicle brakes suddenly at high speed or repeatedly in a short time, the performance of the brake is not easy to decline, which can enable the vehicle to obtain better braking effect, so as to improve the safety of the vehicle.

And because the disc brake has a fast response and the ability to brake at a high frequency, many models use the disc brake in combination with the ABS system, VSC, TCS and other systems to meet the needs of such systems for rapid action.

2、 Disc brake:

Use brake caliper to control two brake pads to clamp the brake disc on the wheel. When the brake pads clamp the disc, friction will occur between them.

The brake discs used in high-performance sports cars are mostly perforated ventilation discs, which have a good cooling effect

Cold air passes through the wheel to cool the brake disc

Function mode of disc brake: as the name implies, disc brake is a brake device that uses static brake discs to clamp the brake discs rotating with the tires to generate friction, so that the wheel rotation speed will be low.

When the brake pedal is pressed, the piston in the brake master cylinder will be pushed and pressure will be built in the brake oil circuit. The pressure is transmitted to the piston of the brake wheel cylinder on the brake caliper through the brake oil. When the piston of the brake wheel cylinder is under pressure, it will move outward and push the brake pad to clamp the brake disc, causing friction between the brake pad and the brake disc to reduce the wheel speed so that the car can slow down or stop.

Advantages of disc brake:

1. Disc brake has better heat dissipation than drum brake, and it will not cause brake recession and brake failure when the brake is continuously applied.

2. The size change of the brake disc after heating does not increase the stroke of stepping on the brake pedal.

3. The disc brake system has a fast response and can perform high-frequency braking actions, so it is more in line with the requirements of the ABS system.

4. The disc brake has no automatic braking effect of the drum brake, so the braking force of the left and right wheels is relatively average.

5. Because the brake disc has good drainage, it can reduce the situation of poor braking caused by water or sediment.

6. Compared with drum brake, disc brake has simple structure and is easy to maintain.

Disadvantages of disc brake:

1. Because there is no automatic braking effect of drum brake, the braking force of disc brake is lower than that of drum brake.

2. The friction area between the brake pad and the brake disc of the disc brake is smaller than that of the drum brake, making the brake force smaller.

3. In order to improve the disadvantages of the above disc brake, it requires greater pedal force or oil pressure. Therefore, the brake disc with larger diameter must be used, or the oil pressure of the brake system must be increased to improve the braking force.

4. The hand brake device is not easy to install. For this reason, a group of drum brake hand brake mechanisms are added to some models with disc brakes on the rear wheels.

5. The brake pads are worn seriously, which may lead to high replacement frequency.