1. The reversing valve of the charging mixer can not reverse or the reversing action is slow, which is generally caused by poor lubrication, stuck or damaged spring, oil or impurities blocking the sliding part. At this time, we should first check whether the oil atomizer of the charging mixer works normally and whether the viscosity of the lubricating oil is appropriate. If necessary, the lubricating oil of the self feeding mixer should be replaced, the sliding part of the reversing valve should be cleaned, or the spring and reversing valve should be replaced.

2. 自上料搅拌车的换向阀经长时间使用后容易出现阀芯密封圈磨损、阀杆和阀座损伤的现象，导致阀内气体泄漏，阀的动作缓慢或不正常换向等故障。此时，需要更换密封圈、阀杆和阀座，或将换向阀换新。

2. After long-term use of the reversing valve of the charging mixer, the valve core seal ring is easy to wear, the valve stem and valve seat are damaged, resulting in gas leakage in the valve, slow valve action or abnormal reversing and other faults. At this time, it is necessary to replace the sealing ring, valve stem and valve seat, or replace the change-over valve.

3. 若电磁先导阀的进、排气孔被油泥或其他杂物堵塞，封闭不严，活动铁芯被卡死，电路有故障等，均可导致换向阀不能正常换向，对于前三种情况应清洗先导阀及活动铁芯上的油泥和杂质，而电路故障一般又可分为电路故障和电磁线圈故障两类。在检查自上料搅拌车电路故障之前，要先将换向阀的手动旋钮转动几下，看换向阀在的气压下是否正常换向，若能正常换向，则是电路有故障；检查时，可以用仪表测量电磁线圈的电压，看是否达到了电压，如果电压过低，应进一步检查控制电路中的电源和相关联的行程开关电路。如果在电压下换向阀不能正常换向，则应检查电磁圈的接头是否松动或接触不实，检查方法：拔下插头，测量线圈的阻值，如果阻值太大或太小，说明电磁线圈已损坏，需要更换。

3. If the inlet and exhaust holes of the solenoid pilot valve are blocked by oil sludge or other impurities, the sealing is not tight, the movable iron core is stuck, and the circuit is faulty, the reversing valve can not be normally reversed. For the first three cases, the sludge and impurities on the pilot valve and movable iron core should be cleaned, and the circuit fault can be generally divided into circuit fault and solenoid coil fault. Before checking the circuit fault of the self feeding mixer, first turn the manual knob of the reversing valve several times to see whether the reversing valve is normal under the rated air pressure. If it can be reversed normally, the circuit is faulty. During the inspection, the voltage of the solenoid coil can be measured by the instrument to see whether the rated voltage is reached. If the voltage is too low, the power supply in the control circuit should be further checked And the associated travel switch circuit. If the directional valve can't reverse normally under rated voltage, check whether the connector of the solenoid coil is loose or not in contact. Inspection method: pull off the plug and measure the resistance of the coil. If the resistance value is too large or too small, it indicates that the solenoid coil has been damaged and needs to be replaced.