现象：汽车行驶中制动时，制动减速度小，制动距离长。
Phenomenon: When the car is braking, the braking deceleration is small and the braking distance is long.
原因：
Reason:
1.总泵有故障。
1. The main pump is out of order.
2.分泵有故障。
2. The pump is out of order.
3.制动器有故障。
3. Brake failure.
4.制动管路中渗入空气。
4. Air seeps into the brake pipeline.
诊断：
Diagnosis:
液压制动系统产生制动效能不良的原因，一般可根据制动踏板行程(俗称高、低)、踏制动踏板时的软硬感觉、踏下制动踏板后的稳定性以及边疆多脚制动时踏板增高度来判断。
The reasons for poor braking efficiency of hydraulic braking system can be generally judged by the stroke of brake pedal (commonly known as high and low), the soft and hard feeling when pedaling brake pedal, the stability after pedaling brake pedal and the increase of pedal height when multi-pedal braking in frontier areas.
1.一般制动时踏板高度太低、制动效能不良。如连续两脚或几脚制动，踏板高度随这增高且制动效能好转，说明制动鼓与磨擦片或总泵活塞与推杆的间隙过大。
1. When braking, pedal height is too low and braking efficiency is poor. If two or more feet are braked continuously, the pedal height increases with this and the braking efficiency improves, which indicates that the gap between the brake drum and the friction disc or the piston of the main pump and the push rod is too large.
2维持制动时，踏板的高度若缓慢或迅速下降，说明制动管路某处破裂、接头密闭不良或分泵皮碗密封不良，其回位弹簧过软或折断，或总泵皮碗、皮圈密封不良，回油阀及出油阀不良。可踏下制动踏板，观察有无制动液渗漏部位。若外部正常，则应检查分泵或总泵故障。
When braking is maintained, if the pedal height drops slowly or rapidly, it indicates that the brake pipeline is broken somewhere, the joint is not sealed properly or the pump cup is not sealed properly, the return spring is too soft or broken, or the main pump cup and ring are not sealed properly, and the return valve and the oil outlet valve are not good. You can first step down the brake pedal and observe if there is any leakage of brake fluid. If the exterior is normal, the fault of the sub-pump or the main pump should be checked.
3.连续几脚制动时,踏板高度仍过低,且在第二脚制动后,感到总泵活塞未回位,踏下制动踏板即有总泵推杆与活塞碰击响声,是总泵皮碗破裂或其连续几脚，回位弹簧太软。
3. The pedal height is still too low when several feet are braked continuously. After the second foot is braked, the piston of the main pump does not return to its position. When the pedal is stepped down, there will be a clash sound between the main pump push rod and the piston, which is the rupture of the main pump cup or its continuous feet, and the return spring is too soft.
4.连续几脚制动时踏板高度稍有增高，并有弹性感，说明制动管路中渗入了空气。
4. The pedal height increases slightly and has a sense of elasticity when several feet are braked continuously, which indicates that air is infiltrated into the brake pipeline.
5.连续几脚，踏板均被踏到底，并感到踏板毫无反力，说明总泵储液室内制动液严重亏损。
5. Continuous several feet, the pedals have been pedaled to the bottom, and feel that the pedals have no reaction, indicating that the main pump storage chamber brake fluid serious loss.
6.连续几脚制动时，踏板高度低而软，是总进油孔中储液室螺塞通气孔堵塞。
6. When several feet are braked continuously, the pedal height is low and soft, which is blocked by the ventilation hole of the screw plug of the storage chamber in the total oil intake hole.
7.一脚或两脚制动时，踏板高度适当，但太硬制动效能不良。应检查各轮磨擦片与鼓的间隙是否太小中高速不当。若间隙正常，则检查鼓壁与磨擦片表面状况。如正常，再检查制动蹄弹簧是否过硬，总泵或分泵皮碗是否发胀，活塞与缸壁配合是否松旷。如均正常，则应进而检查制动软管是否老化不畅通。
7. When one foot or two feet are braked, the pedal height is appropriate, but the braking efficiency is too hard. Whether the clearance between the friction disc and the drum is too small, medium and high speed should be checked. If the clearance is normal, check the drum wall and the surface condition of the friction sheet. If normal, check whether the brake shoe spring is too hard, whether the main pump or sub-pump cup is inflated, and whether the piston and cylinder wall fit is loose. If they are all normal, the brake hose should be further checked for ageing and obstruction.
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