1. Danger of oil overheating

　　挖掘机液压系统中液压油的过热会降低液压油的热稳定性和化学稳定性。油的粘度会降低和增加泄漏;液压泵、气缸、阀门等部件磨损增加;滑阀操作不当，造成了事故。

　　The overheating of hydraulic oil in excavator hydraulic system will reduce the thermal and chemical stability of hydraulic oil. The viscosity of oil will reduce and increase leakage; the wear of hydraulic pump, cylinder, valve and other components will increase; the improper operation of slide valve will cause accidents.

　　2. 油温过热原因

　　2. Cause of oil temperature overheating

　　液压系统的过热的主要原因是不合理的设计,外部热源的影响,如引擎,劣质的选择液压油或粘度的变化,油不足,过低的压力阀阀芯的调整或频繁动作,污垢的散热器和冷却风扇的速度减少。

　　The main causes of the overheating of the hydraulic system are unreasonable design, the influence of external heat sources, such as the engine, the poor selection of hydraulic oil or the change of viscosity, the lack of oil, the adjustment or frequent action of the valve element of the low pressure safety valve, and the decrease of the speed of the dirt radiator and cooling fan.

　　3.防止油过热的措施

　　3. Measures to prevent oil overheating

　　(1)改进设计，精心制作。

　　(1) improve the design and make it carefully.

　　(2)寻找外部热源，或隔离。如果加油量超过油标线，挖掘机会在阻尼器转向过程中产生大量热量，并传递给液压泵，导致系统升温。阻尼箱内的油应排放到标准油位。

　　(2) find external heat source, eliminate or isolate. If the amount of oil filling exceeds the oil mark, a lot of heat will be generated during the turning process of the damper, which will be transmitted to the hydraulic pump, causing the system to heat up. The oil in the damping box shall be drained to the standard oil level.

　　(3)液压油按挖掘机泵、阀组件产品说明书中规定的液压油选择。如果规格的阀门类型元件是缺失的，可以根据泵来选择。主泵为柱塞泵，其许用粘度范围为4~ 76mm2 /s，选择16~ 47mm2 /s为宜，工作压力一般在35mpa以上;工作温度为5~40℃时，可选用l-hm32、l-hm46抗磨液压油，工作温度为40~80℃时，可选用l-hm46、l-hm68抗磨液压油。

　　(3) the hydraulic oil shall be selected according to the hydraulic oil brand specified in the product manual of excavator pump and valve assembly. If the size of the valve type element is missing, it can be selected according to the pump. The main pump is a plunger pump, its allowable viscosity range is 4 ~ 76mm2 / s, 16 ~ 47mm2 / S is suitable, and the working pressure is generally above 35MPa; when the working temperature is 5 ~ 40 ℃, l-hm32 and l-hm46 antiwear hydraulic oil can be selected, and when the working temperature is 40 ~ 80 ℃, l-hm46 and l-hm68 antiwear hydraulic oil can be selected.

　　(4)完善挖掘机液压系统的技术条件检查制度，认真实施日常检查和维护。检查各连接处是否有泄漏，油箱内的油量是否充足，泵的工作温度是否正常，过滤器是否堵塞等，可以有效防止液压油温度过高。

　　(4) improve the technical condition inspection system of excavator hydraulic system, and carefully implement daily inspection and maintenance. Check whether there is leakage at each connection, whether the oil volume in the oil tank is sufficient, whether the working temperature of the pump is normal, whether the filter is blocked, etc., which can effectively prevent the hydraulic oil temperature from being too high.

　　(5)检查溢流阀调整后的压力、弹簧、阀芯、阀座。根据阀的启闭特性，调节压力(启闭压力)应大于系统额定压力的10%。然后观察弹簧是否弯曲(其轴与端面不垂直)、断裂，如有必要应更换;检查主阀芯和先导阀芯是否完全畅通，应及时清洗阻尼孔，防止堵塞时;检查主阀芯，如修复阀芯不灵活，需重新组装，如系统杂质过多，造成主阀芯不灵活，需更换液压油;检查先导阀芯是否与阀座接触良好。密封油表面的圆度误差应控制在5 ~ 10微米。

　　(5) focus on the pressure, spring, valve core and valve seat after the adjustment of relief valve. According to the opening and closing characteristics of the safety valve, the regulating pressure (opening and closing pressure) shall be greater than 10% of the rated pressure of the system. Then observe whether the spring is bent (its shaft is not perpendicular to the end face), broken, and replace if necessary; check whether the main valve core and pilot valve core are completely unblocked, and clean the damping hole in time to prevent blocking; check the main valve core, if the repair valve core is not flexible, it needs to be reassembled, if there are too many system impurities, the main valve core is not flexible, it needs to replace the hydraulic oil; check whether the pilot valve core is with the valve The seat contacts well. The roundness error of sealing oil surface shall be controlled within 5-10 μ M.

　　(6)检查并清洗盘管和多管冷却器。清洗时，先用氢氧化钠和碳酸钠去油，再用温水清洗。用20%~30%稀硫酸溶液浸泡清洁40分钟，水温40~60℃。之后用温水清洗。在10%氢氧化钠溶液中浸泡，清洗15分钟，溶液温度40~60℃。之后，用蒸汽或温水清洗。由于冷却器造型比较复杂，如果散热器积垢太难以，应进行更换。

　　(6) check and clean coil and multi tube cooler. When cleaning, first use sodium hydroxide and sodium carbonate to remove oil, and then use warm water to clean. Soak in 20% ~ 30% dilute sulfuric acid solution for cleaning for 40 minutes, and the water temperature is 40 ~ 60 ℃. Then wash with warm water. Finally, soak in 10% sodium hydroxide solution, wash for 15 minutes, and the solution temperature is 40 ~ 60 ℃. After that, wash with steam or warm water. Due to the complex shape of the cooler, if the radiator scale is too difficult to remove, it should be replaced.

　　(7)检查冷却风扇胶带，根据需要调整。

　　(7) check the cooling fan tape and adjust it as required.