Olfactory diagnosis: smell hydraulic oil through nose. If the smell of hydraulic oil is abnormal, it means that hydraulic components such as hydraulic pump are partially heated, resulting in combustion and smoke of hydraulic oil. Therefore, hot components can be identified. Check the hydraulic oil for unpleasant or pungent smell. If the hydraulic oil is seriously contaminated, it should not be used again.

视觉诊断方法：用肉眼观察液压系统的工作状态，观察液压系统各压力测量点的压力值和温度变化，检查机油是否清洁，油量是否充足。观察液压阀和管接头，液压缸端盖和液压泵驱动轴是否漏油。观察从设备加工的产品或进行性能测试，以确定移动机构的工作状态，系统压力和流量的稳定性以及电磁阀的工作状态。

Visual diagnosis method: observe the working state of the hydraulic system with the naked eye, observe the pressure value and temperature change of each pressure measuring point of the hydraulic system, and check whether the oil is clean and sufficient. Observe the hydraulic valve and pipe joint, the end cover of hydraulic cylinder and the drive shaft of hydraulic pump for oil leakage. Observe the products processed from the equipment or conduct performance test to determine the working state of the mobile mechanism, the stability of system pressure and flow and the working state of the solenoid valve.

听觉诊断：判断液压系统或组件是否正常工作是人们的耳朵。聆听液压泵和液压系统的噪音；聆听溢流阀和其他组件的异常声音；当影响太大时，听工作表；听听液压缸底部的活塞声音。

Auditory diagnosis: it is people's ears to judge whether the hydraulic system or components are working properly. Listen to the noise of hydraulic pump and hydraulic system; Listen to the abnormal sound of overflow valve and other components; When the impact is too great, listen to the worksheet; Listen to the piston sound at the bottom of the hydraulic cylinder.

触觉诊断方法：用手触摸运动部件的温度和工作状态，并用手触摸液压泵壳体，燃油箱外壁和阀体壳体的温度。正常温度应在55°C左右。如果温度超过60°C，请检查原因。用手触摸运动的零件和管道，以感觉到明显的振动。

Tactile diagnosis method: touch the temperature and working state of moving parts by hand, and touch the temperature of hydraulic pump housing, outer wall of fuel tank and valve body housing by hand. The normal temperature should be about 55 ° C. If the temperature exceeds 60 ° C, check the cause. Touch moving parts and pipes with hands to feel obvious vibration.