Technical Essentials - Common Faults and Solutions of Hydraulic Systems

1. No-load debugging stage

The failure rate of the hydraulic system is the highest during the no-load commissioning stage, and the existing problems are rather complex. The characteristic is that issues such as design, manufacturing, installation and management are intertwined. In addition to mechanical and electrical issues, common faults in general hydraulic systems include:

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(1) Leakage at the connection of components.

(2) The valve core is stuck or does not move flexibly, causing the actuator to malfunction.

(3) The damping hole is blocked, causing unstable system pressure or inability to adjust the pressure.

(4) The valve components are poorly equipped with springs or seals, or the pipelines are wrongly connected, causing confusion in operation.

(5) Improper design or selection can cause the system to overheat or operate uncoordinated.

(6) Poor processing quality of hydraulic components or poor installation quality leads to inflexible operation of valves.

(7) The design of the oil circuit block channel is incorrect.

(8) The components of the control system are not working properly.

2. Load trial operation stage

After the no-load commissioning was completed, many problems have been solved. Moreover, after a period of no-load operation and running-in, the system oil is relatively clean, and the phenomena of valve core jamming, sluggish movement and damping hole blockage are rare. The main problems are manifested in the following aspects:

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(1) The position accuracy and synchronization accuracy do not meet the requirements.

(2) The system back pressure is too high, and the design pressure cannot drive the load.

(3) Improper design selection causes the system to overheat.

(4) The set values of the pressure elements are unreasonable.

(5) The oil filter is clogged.

3. Stable operation stage

After the hydraulic system has been running under load for a period of time, there will be a stable operation period during which major problems are unlikely to occur. The main issues are mainly manifested in the following aspects:

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Leakage caused by aging, damage to the seal and loose bolts, etc.

(2) Faults are caused by clogged filters, oil problems, etc.

(3) Faults are caused by incorrect operation and maintenance, etc.

If the cleanliness of the system is not well controlled during the initial commissioning and operation, and the oil is severely contaminated, after the system has been working for several months or even longer, due to severe wear, the pump and other components will experience significant internal leakage, affecting the normal operation of the system.

4. A period with a high incidence of component failure

After the operating time of the hydraulic system reaches the service life of its components, pumps, motors and other components start to malfunction one after another. At this stage, the diagnosis of problems and faults mainly focuses on the identification of component faults. The problems are mainly manifested in the following aspects:

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(1) Severe wear of components leads to increased internal leakage in the system.

(2) The spring of the pressure element becomes soft, causing abnormal pressure.

(3) Severe wear of the pump results in the oil supply volume and pressure failing to meet the requirements.

(4) The cylinder seal is severely damaged.

Diagnostic methods for common faults

1. Simple fault diagnosis method

Ask experienced personnel to understand the operation status of the equipment.

(2) Check whether there are any problems with the pressure, speed, oil, leakage, vibration, etc. of the hydraulic system.

(3) Listen to the sound of the hydraulic system: impact sound; Noise and abnormal sounds of the pump; Determine whether the hydraulic system is working properly.

(4) Check the temperature rise, vibration, crawling and the tightness of the connection points to determine whether the working condition of the moving parts is normal.

2. Analysis method of hydraulic system schematic diagram

Based on the schematic diagram of the hydraulic system, analyze the faults that occur in the hydraulic transmission system, identify the location and cause of the faults, and propose methods to eliminate the faults.

By comparing and analyzing the action cycle table, faults are judged and methods for troubleshooting are proposed.

3. Other analytical methods

When a hydraulic system malfunctions, logical analysis should be conducted based on the principle of the hydraulic system or methods such as causal analysis should be adopted to eliminate the faults one by one, and finally the faulty part should be identified.