How often should Drum Brake Linings be replaced?

Drum Brake Linings are one of the key components in the vehicle braking system. Their main function is to slow down or stop the wheels through friction when the brake pedal is pressed. Similar to disc brake pads, drum brake linings will also wear out due to long-term use, so they need to be checked and replaced regularly to ensure driving safety.

1. Working principle of drum brake linings
In a drum brake system, the brake linings are installed inside the brake drum. When the driver presses the brake pedal, the hydraulic system pushes the brake shoe to expand outward, so that the linings are close to the inner wall of the brake drum, thereby generating friction to slow down or stop. Due to this working method, the brake linings will gradually wear out as the use time increases.

2. Factors affecting the life of drum brake linings
Driving habits
Bad driving habits such as frequent emergency braking and long-term use of brakes downhill will accelerate the wear of brake linings.
Driving environment
Frequent starting and stopping in congested urban roads, or frequent driving in mountainous areas, will increase the burden on the brake system and shorten the service life of the linings.
Vehicle type and use
Trucks, SUVs or vehicles that are often loaded have greater demands on the brake system, so the linings wear faster.
Brake material quality
Brake linings of different materials (such as asbestos, semi-metallic, ceramic, etc.) have different wear resistance, and high-quality linings are usually more durable.
Brake system maintenance status
If the brake shoes, return springs, brake drums and other components fail or age, it will also affect the normal operation of the linings and cause premature wear.

3. Replacement cycle of drum brake linings
Generally speaking, the replacement cycle of drum brake linings is about 30,000 to 70,000 kilometers, but this data is only a rough reference, not an absolute standard. The specific replacement time should be determined based on the following points:

1. Combined judgment of mileage and time
Although the drum brake linings of some vehicles can be used for more than 50,000 kilometers, it is also possible that they need to be replaced before 30,000 kilometers, especially for vehicles that often drive in harsh environments.

2. Abnormal sound prompts
If you hear "crunching", "scratching" or "rubbing metal" sounds during braking, the lining may be severely worn or even worn through the metal bracket, and must be replaced immediately.

3. Reduced braking performance
Softer brakes, longer braking distances, abnormal foot feel, etc. may be manifestations of brake lining wear or other brake system problems.

4. Regular inspection to detect wear
It is recommended to check the brake system every 10,000-20,000 kilometers. Professional technicians can determine whether replacement is required by visual inspection or thickness measurement.

5. Check whether the automatic adjuster is working properly
There is an automatic adjustment device in the drum brake system to maintain the proper gap between the brake lining and the brake drum. If the adjuster fails, it may cause the braking effect to deteriorate and accelerate the wear of the lining.

4. When must the drum brake lining be replaced?
The following are several situations where replacement is clearly required:

The thickness of the lining is less than 1.5 mm (refer to the vehicle maintenance manual for specific values)
The lining surface has obvious cracks or peeling
The lining rivets have been exposed or are about to fall off
The inner wall of the brake drum has obvious scratches or grooves (may be caused by excessive wear of the lining)

5. Precautions for replacing drum brake linings
Replace in pairs: It is recommended to replace the brake linings on both sides at the same time to ensure balanced braking force.
Check the brake drum status: If the brake drum is severely worn or deformed, it should be replaced or repaired together.
Adjust the brake clearance: After replacement, readjust the clearance between the brake shoe and the brake drum.
Lubricate moving parts: During the replacement process, apply special grease to the brake shoe fulcrum, return spring and other parts to avoid jamming.
Test the brake performance: After the replacement is completed, the braking effect should be tested at low speed to ensure safety.

As an important part of the automobile braking system, drum brake linings are directly related to driving safety. Although the replacement cycle is generally 30,000 to 70,000 kilometers, the actual replacement time should be determined according to driving habits, road conditions, brake system status and regular inspection results.

It is recommended that car owners conduct regular inspections according to the maintenance recommendations of the vehicle manufacturer and go to a professional repair shop for diagnosis and replacement in a timely manner if any abnormality is found. Only by maintaining a good brake system can traffic accidents be effectively prevented and the safety of drivers and passengers be guaranteed.