1. The pedal is too far away.
2. There is too little brake fluid in the brake master cylinder, or the hole is blocked by impurities, and the parts of the master cylinder are aging and expanding, even deformed or turned over.
3. The parts of the brake master cylinder are severely worn, which leads to looseness and oil leakage. The oil return valve is not well sealed, and the tension spring of the oil outlet valve is broken.
4. The brake cylinder parts are aging and expanding, the piston is blocked, and the movable parts of the cylinder are severely worn, resulting in loose connection and oil leakage.
5. The brake shoe is severely worn, the brake clearance is relatively large or the clearance is not installed properly.
6. The brake drum is not round, which causes the phenomenon of gouging or wear. The brake shoes are stained with oil, burnt and rotted, and the rivets are obvious.
7. There is oxygen in the brake system, or the temperature in the brake system is too high. The brake fluid in the pipeline is vaporized, causing air resistance.
8. The oil pipe is not round, the connection is not tight, there is oil leakage, the hose is aging, broken or blocked by impurities
