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Views: 25 Author: Site Editor Publish Time: 2025-09-02 Origin: Site
A brake drum is a component installed on a car wheel hub that rotates with the wheel. It is an indispensable component of a drum brake system. Its shape resembles a bell, and it is typically made of gray cast iron (such as HT200 or HT300 grades). The base structure of the brake drum is primarily pearlite, with small amounts of ferrite and cementite. Graphite primarily exists in the A-type form, appearing as long flakes.
The brake drum is fixed to the tire and rotates synchronously with it, serving as a critical component for achieving braking functionality. During braking, two pairs of crescent-shaped brake shoes are subjected to pressure from the piston, causing them to press tightly against the inner wall of the brake drum's drum chamber. The resulting friction between the two components brings the wheel to a stop, thereby achieving the braking effect. A drum brake system typically consists of a brake base plate, brake caliper, brake shoes, etc., and is connected to the brake drum via a series of linkages, springs, and pins.
Casting is a commonly used process for producing brake drums. To enhance performance, alloys such as copper (Cu) and chromium (Cr) are often added. Compared to disc brakes, drum brakes can have a smaller drum diameter than brake discs while achieving the same braking torque. Therefore, drum brakes are primarily used on the rear wheels of large vehicles to ensure sufficient braking capacity. For vehicles with heavy loads requiring strong braking power, drum brakes are an ideal choice.
Drum brakes have their own advantages, performing exceptionally well in terms of braking force and meeting the braking requirements of large vehicles. However, they also have some drawbacks, such as poor water resistance. Water entering the brake drum can reduce braking effectiveness. Therefore, after a vehicle has driven through water, the driver should apply the brakes for a short distance to drain any water from the brake drum. Additionally, to ensure the normal operation of the brake pads, they should be adjusted regularly. It is generally recommended to perform maintenance every 3–4 months to maintain braking efficiency.
In the commercial vehicle sector, such as trucks and buses, brake drums are widely used. This is because commercial vehicles typically need to carry heavy loads and require high braking force, while drum brake systems can provide significant braking torque. Additionally, drum brake systems have a relatively simple structure, lower costs, and are easier to maintain, making them suitable for the characteristics of commercial vehicles. For example, on some heavy-duty trucks, brake drums can quickly bring high-speed vehicles to a stop, ensuring driving safety.
Although many passenger vehicles now use more advanced disc brake systems, some models still use brake drums on the rear wheels. This is primarily due to cost and space considerations. Brake drums have a compact structure and occupy minimal space, helping to save space in the vehicle. Additionally, for some small passenger vehicles with less stringent braking requirements, drum brakes can meet daily braking needs. For example, the rear wheels of some economy sedans use drum brake systems.
• Traditional cast iron brake drums: Widely used in the rear wheels of ordinary commercial vehicles and some passenger cars, meeting basic braking requirements.
• New ceramic brake drums: With their excellent performance and durability, they are gradually entering the high-end automotive and racing fields, providing more stable braking performance and a longer service life.
• Heat Dissipation Improvements: To address the poor heat dissipation performance of drum brakes, some new brake drums incorporate special heat dissipation structures or coatings to enhance braking stability under high temperatures.
• Thermal Fading Control: By optimizing material and structural design, heat accumulation during braking is reduced, minimizing the risk of deformation in brake shoes and drums, and improving braking efficiency.
If you notice a significant increase in braking distance, a softer brake pedal, or the need for greater force to achieve braking during driving, this may indicate severe wear or malfunction of the brake drum. In such cases, the condition of the brake drum should be inspected promptly, and replacement should be performed if necessary.
When the brake drum has issues, it may produce abnormal noise. For example, hearing sharp friction sounds or metal clanging during braking may indicate excessive clearance between the brake shoes and drum body or severe wear of the friction material. If this occurs, the brake drum should be inspected promptly.
If the vehicle vibrates when braking, especially at high speeds or during emergency braking, this may be caused by an uneven or deformed brake drum surface. Deformation of the brake drum can result in uneven contact between the brake shoes and the drum body, leading to vibration. Once brake vibration is detected, the brake drum should be inspected and addressed promptly.
Regularly inspecting the wear and tear of brake drums is extremely important. Generally, it is recommended to inspect brake drums after a certain number of miles driven or at regular intervals. Inspection items include the degree of wear on the drum body, the thickness of the brake shoes, and the elasticity of the return springs. If severe wear on the drum body or excessively thin brake shoes are detected, they should be replaced promptly.
Maintaining the cleanliness of the brake drum also helps extend its service life. During daily use, the brake drum may accumulate dust, sand, and other contaminants, which can accelerate wear. Therefore, it is necessary to clean the brake drum regularly to remove surface contaminants. Specialized brake cleaners can be used for cleaning, but care must be taken to avoid splashing the cleaner onto the friction material of the brake shoes, as this may impair braking performance.
3) Avoid Excessive Braking
Excessive braking can cause the brake drum to overheat, accelerating its wear and aging. During driving, avoid sudden braking and prolonged continuous braking whenever possible. Use the braking system appropriately to reduce the load on the brake drum. For example, anticipate road conditions in advance while driving and use intermittent braking to decelerate, which can effectively lower the temperature of the brake drum.
Although brake drums may seem insignificant, they play a crucial role in a vehicle's braking system. Understanding the structure, operating principles, application scenarios, advantages and disadvantages, as well as maintenance and care methods of brake drums is essential for vehicle owners. Only by properly using and maintaining brake drums can one ensure good braking performance and driving safety. With the continuous advancement of technology, brake drums will continue to innovate and improve, bringing better performance and reliability to the vehicle's braking system.Our EV company produces different brake pads and provides high-quality, safe and reliable products. If you are looking for suitable brake drums, please visit our company website:https://www.evfriction.com, or contact us by phone:+86-13363216781, our service will definitely not disappoint you.
