1、 Brake system malfunction
Brake cylinder malfunction:
The brake cylinder piston does not return to its original position: This may be due to the piston rusting, jamming, or damage to the sealing ring inside the cylinder, causing the piston to be unable to move normally. When the piston cannot return, the brake shoes always come into contact with the brake drum or brake disc, causing the brake to lock up.
Cylinder leakage: Brake fluid leaking from the cylinder can cause a decrease or loss of brake pressure, making it impossible to release the brake properly. Leakage may be caused by aging, damage, or improper installation of the cylinder seal.
Brake master cylinder malfunction:
Master cylinder piston not returning: Similar to the master cylinder piston not returning, if the master cylinder piston cannot return normally, it will continue to apply pressure to the brake system, causing the brake to lock up. Possible reasons include rusting inside the master cylinder, spring failure, etc.
Improper adjustment of master cylinder: If the push rod of the master cylinder is adjusted too long, it will keep the brake system in working condition, and even if the driver releases the brake pedal, the brake cannot be released.
2、 Brake pad and brake disc (drum) issues
Excessive wear of brake pads:
When the brake pads wear to the limit, their back plate may come into direct contact with the brake disc (drum), generating excessive friction and causing the brake to lock up. In addition, excessively worn brake pads may break or fall off, get stuck in the brake system, and cause the brakes to lock up.
Brake disc (drum) deformation:
If the brake disc (drum) deforms due to high temperature, external forces, or other reasons, its surface will no longer be smooth, the contact area with the brake pad will increase, and the friction force will also increase accordingly, which can easily cause the brake to lock up. For example, frequent use of brakes during long-term downhill driving can cause the brake disc (drum) to overheat, leading to deformation.
3、 Other factors
ABS system malfunction:
Anti lock braking system (ABS) can prevent brake lock up and improve the braking stability of the vehicle. If the ABS system malfunctions, such as sensor damage, control module failure, etc., it may cause the brakes to lock up. For example, if the ABS sensor cannot accurately detect the speed of the wheels, the control module may mistakenly determine that the vehicle is in a locked state and continue to apply brake pressure.
Adverse road conditions or improper operation:
When driving on harsh road conditions such as mud, ice, and snow, the wheels may get stuck, causing uneven force on the brake system and easily leading to brake lock up. In addition, if the driver brakes frequently during driving, or if the vehicle experiences severe jolts during braking, it may also cause the brakes to lock up.