When braking, hydraulic pressure is used to push the brake shoe into contact with the inner edge of the brake drum, and the friction generated by the contact can restrain the rotation of the tire to achieve the purpose of braking. The drum brake is composed of the brake base plate, brake cylinder, brake shoe, and other related connecting rods, springs, pin nails, and brake drum. Drum brakes have lower cost and higher absolute braking force. The inner surface of the brake drum of the drum brake is the position where the brake device generates the braking torque.
The principle of drum brakes:
The drum brake is a brake device that uses the stationary brake pads in the brake drum to rub the brake drum that rotates with the wheel to generate friction to reduce the rotation speed of the wheel. The drum brake on the car is simply a brake oil pump. , Piston, brake pads, and drum chamber. When braking, the piston is pushed by the high-pressure brake oil of the brake cylinder to exert force on the two half-moon-shaped brake shoes to press against the inner wall of the drum, and the brake drum is blocked by friction. Rotate to achieve the braking effect.
The advantages and disadvantages of drum brakes:
Advantage:
1. The drum brake has a good self-braking effect. Because the brake is used to stretch the film, the wheel rotates and the brake drum is twisted at an angle (of course not so large that you can easily see it). The brake is used to make the film out. The greater the tension (brake braking force), the more obvious the situation. Therefore, generally, large vehicles still use drum brakes. In addition to the lower cost, the difference between the drum brakes of large vehicles and small vehicles may only be the large-scale pneumatic assistance. Small cars use vacuum assistance to help brakes.
2. Lower cost: Drum brakes have a lower manufacturing technology level and are the first to be used in brake systems, so the manufacturing cost is lower than that of disc brakes.
3. The hand brake mechanism is easy to install. Some models with disc brakes on the rear wheels will install a drum brake hand brake mechanism in the center of the brake disc.
Disadvantages:
1. The diameter of the brake drum of the drum brake will increase after being heated, which will increase the stroke of stepping on the brake pedal, which is likely to cause the brake response to be less than expected. Therefore, when driving a vehicle with drum brakes, try to avoid continuous braking that causes the brake pads to thermally degenerate due to high temperatures.
2. The brake system reacts slowly, and the pedaling force of the brake is not easy to control, which is not conducive to high-frequency braking actions.
3. There are many parts with complex structures, and the brake clearance must be adjusted, which makes maintenance difficult.