1.Fault Scope
This refers to the scope of the fault. Some faults are single - natured, while others are comprehensive and overall. The former is caused by the abnormality of individual factors. The latter involves multiple links and parts. For example, dirty hydraulic oil can cause valve cores to get stuck in multiple places of the hydraulic system and electromagnets to burn out. When the equipment is used for a long time and there is wear and tear in many places, it will lead to a decline in system pressure and flow, which belongs to comprehensive faults.

2.Fault Severity
It means the degree of seriousness of the fault, that is, the degree of damage to the hydraulic device. Severe faults have high severity, while minor faults are the opposite. On site, attention should be paid to detecting the signs of faults to avoid severe faults. Minor faults have insufficient and unclear information, making fault analysis more difficult.

3.Deterioration Rate
This is the speed at which the fault occurs and develops. Some faults occur suddenly, while others develop gradually. Sudden - type faults include part fatigue fracture and wire shedding. For sudden - type faults, attention should be paid to mastering the omens of the faults. For gradual - type faults, long - term monitoring should be carried out to figure out their development trends.

4.Fault Timeliness
It refers to the duration of the fault's effect. Some faults are instantaneous, intermittent, or come and go. For example, contaminants may block the throttle orifice, and then the oil 冲走 (flushes away) the contaminants. Another example is that due to loose installation of the travel switch, the directional control valve may not shift in time. Some faults, once they occur, can only restore function after repairing or replacing parts, and such faults are permanent faults. The causes of temporary faults are external, while the direct causes of permanent faults are inside the components.

5.Fault Frequency
This is the frequency at which faults occur. Some faults occur frequently, while others occur occasionally. For frequently occurring faults, strong measures should be taken to eliminate their root causes. Analyzing occasional faults is much more difficult.