Confirm that the vacuum booster and hydraulic transmission are working properly, and then check the wheel brakes. Under the driving state (30~50km/h), press the brake pedal hard and make the following judgment according to the phenomenon:
1) If the braking performance is poor, it may be due to the following reasons: friction of the brake disc (drum) or friction lining, oil stains on the brake drum, water stains in the brake drum (rainy days), and excessive temperature of the brake drum ( There are many steep slopes on Panshan Road), the eccentric support pin of the brake shoe is rusty or rusty (it is easy to appear after the vehicle is left for a long time).
2) If the direction is deviated during braking, check whether the friction wear of each wheel brake is uniform, whether the brake clearance is appropriate, and whether the proportional valve is effective.
3) After driving for 20 kilometers, touching the brake drum or brake disc with your hand and feeling particularly hot, the brake return device fails.
The hydraulic brake device converts the pedal force into hydraulic energy to transmit the braking force. The transmission mechanism is simple, but the braking torque generated by the brake is linear with the pedal force. If the adhesion between the tire and the road surface is sufficient, the car The braking force received is linearly related to the pedal force. This performance is called brake pedal feeling (commonly known as foot feeling), so the driver can directly feel whether the various working conditions of the brake device of the car are normal, so as to quickly diagnose. The common faults of hydraulic brake system are: poor braking like brake biting.