1、The brake cylinder does not return to its position, and in severe cases, abnormal noise will occur and the wheels will lock.

2、If the brake master cylinder cup is stuck and does not return, it is generally caused by water or other impurities entering the brake system, or the system has not been cleaned before replacing other brands of brake fluid, causing the brake master cylinder cup to swell and cause locking.

3、The wheels lock statically when placed. After the vehicle is parked statically, locking occurs after being left overnight. This phenomenon mostly occurs on vehicles with drum brakes on the rear wheels. The friction pad is a semi-metal-based brake pad, and the brake drum is a cast iron part. When the handbrake is in the parking state, it is tightened. The brake pads and brake drums are tightly attached to each other, and the metal iron oxidizes and rusts when exposed to water, causing adhesion.

Solution: Spray rust remover or sandpaper.

4、The vacuum booster pump is faulty. Check whether the sealing ring is worn and elastic.

5、The braking force is too strong. Brake lock means that the wheels stop rotating after receiving strong braking force. Due to the inertia generated by the vehicle speed, even if the wheels stop rotating, the vehicle is still sliding forward.

6、The brake piston does not return or returns poorly due to poor material performance of the square sealing ring or poor coordination between the square sealing ring, the inner diameter of the caliper and the caliper piston, causing the return amount of the square sealing ring to be too small, resulting in wheel drag or even Hug to death.