Brake drum introduction

by:FUSAI     2020-03-24

The brake drum is a cast iron piece shaped like a tambourine, which is fixed to the tire and rotates at the same speed. When braking, oil pressure is used to push the brake shoes (Brake Shoes) to contact the inner edge of the brake drum, and the friction generated by the contact is used to suppress the tire rotation to achieve the purpose of braking. The drum brake is composed of the brake floor, brake cylinder, brake shoes and other related links, springs, spikes, and brake drum. At present, it is only commonly used on the rear wheels. Drum brakes have lower costs and higher absolute braking power, and are used more often on the rear wheels of small cars. However, its wear rate is high, so the overall cost is high at the same time. Spiral groove brake drum Introduction If the drum body does not generate thermal cracks during braking and there is no quality defect in casting, then the general quality brake drum can be called 'brake does not break' just because the brake drum is a brittle gray cast iron material and in high temperature and high pressure environment 1] It is a physical characteristic of cast iron materials that fatigue cracks are formed on its surface. It is an irresistible objective law. With the extension and penetration of cracks on the drum body, the mechanical strength of the drum body rapidly declines, and the brake will inevitably break. Machining spiral grooves can change the friction properties between the drum hoofs, changing it from 'face' contact friction to 'belt' contact friction. Following the lateral movement of the helix and the 'continuous' friction displacement and 'intermittent' friction, the grooved brake drum brings the following benefits in practice: 

Features 1. The groove can block the free extension of some surface cracks, 

2. The groove can resist the thermal deformation of the drum body and maintain the inherent shape of the high temperature state. 

3. The groove creates a heat exhaust channel for the center of the drum body. 

4. The groove can overcome the slip caused by oil and water soaking and prevent brake failure. 

5 Spiral groove brake drum can extend the service life of the brake. Broadband friction and intermittent friction can truly control the temperature rise of the drum body. The low temperature is very beneficial to vehicle braking. It also further proves the safety and scientificity of the spiral groove on the brake drum wall. Drum brake advantage Self-braking effect: The drum brake has a good self-braking effect. Due to the brakes, the discs are flared, and the wheels are rotated with the flared brake drums twisted at an angle. (Of course it will not be so large that you can easily see it) The greater the off-chip tension (braking braking force), the more obvious the situation. Therefore, drums are generally used in large vehicles, except for lower costs. The difference between the drum brakes of large cars and small cars may only be the use of large-scale pneumatic assistance, while small cars use vacuum assistance to help brake. Low cost: Drum brake manufacturing technology is low-level, and it is also the first to be used in brake systems, so the manufacturing cost is lower than that of disc brakes. Disadvantage Because the drum brake brake seals the brake disc inside the brake drum, the brakes cause the scraped pieces to wear away, which affects the contact surface between the brake drum and the brake pad and affects the braking performance. Disc brake advantage Brake drum Because the brake system is not sealed, fine particles of brake wear are constantly deposited on the brakes. The centrifugal force of the disc brakes can throw out all water, dust and other pollution to maintain a certain cleanliness. In addition, because the disc brake parts are independent, it is easier to maintain than the drum brake. Disadvantage Disc brakes are generally better than drum brakes except for the higher cost, but this is the fatal injury of this one. People love money. Unless you are very rich, you basically buy things first. Think about money first, do you say yes or no? The disc brake is also called a disc brake, as its name implies, it is named after its shape. It is controlled by hydraulic pressure and its main parts include brake discs, sub-pumps, brake calipers, oil pipes, etc. The brake disc is made of alloy steel and fixed on the wheel, and rotates with the wheel. The partial pump is fixed on the bottom plate of the brake. The two friction plates on the brake caliper are mounted on both sides of the brake disc, respectively. The piston of the cylinder is driven by the hydraulic pressure from the oil pipe to push the friction plate against the brake disc to cause friction braking. It acts as if the rotating plate is clamped with pliers, forcing it to stop. The brake has fast heat dissipation, light weight, simple structure and convenient adjustment. Especially under high load, it has good high temperature resistance, stable braking effect, and not afraid of muddy water. When driving in winter and bad road conditions, disc brake is easier to stop the car in a shorter time than drum brake. Some disc brakes also have many small holes in the brake discs to accelerate ventilation and heat dissipation and improve braking efficiency. In contrast, drum brakes, due to their poor heat dissipation performance, can accumulate a large amount of heat during braking. Under the influence of high temperature, the brake shoe and drum are more likely to undergo extremely complicated deformation, and it is easy to cause brake decay and chattering, which causes the braking efficiency to decrease. Of course, disc brakes have their own drawbacks. For example, the requirements for the manufacture of brakes and brake lines are high, the friction linings have a large amount of wear and are expensive, and because the area of the friction linings is small, the relative frictional working surface is also small, and the required brake hydraulic pressure is high. Vehicles that require power assist devices can only be used, so they can only be used on light vehicles. The drum brake is relatively cheap and relatively economical.                                

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