1. Problem description and scope
This is a manual for diagnosing and correcting hydraulic actuator overheating problems. The problem can occur in various types of industrial equipment, including hydraulic pumps, actuators and control systems. According to the severity of the problem, it can be classified as critical (system failure), medium (reduced performance) or minor (temporary reduced performance).
2. Safety and measures
Warning: Before performing any diagnostic actions, perform a lockout/tagout procedure to prevent an unexpected system failure. Use personal protective equipment (insulating gloves, goggles, protective equipment against harmful substances, if necessary).
3. Necessary diagnostic tools
| Name of the tool | Model/Spec | Measuring range | The goal |
|---|---|---|---|
| Thermal camera | FLIR A320 | -20°C to 1200°C | Detection of overheating of components |
| Multimeter | Fluke 87V | 0–2000V, 0–200A | Measurement of voltage and current |
| Vibration analyzer | Keysight 35670A | 0–100 kHz | Detection of vibrational deviations |
| Pressure manometer | Testo 510 | 0–100 bar | Pressure measurement in the system |
| Thermometer | Testo 826 | –50°C to 1000°C | Temperature measurement in working conditions |
4. First review and inspection
| Point | action |
|---|---|
| 1 | Determine the temperature of the system under operating conditions |
| 2 | Check the condition of the amount of working fluid |
| 3 | Write down a history of anxiety |
| 4 | Check for hardware or environment changes |
| 5 | Pay attention to changes in sounds or vibrations |
5. Systematic diagnostic scheme
- Symptom: Overheating of the hydraulic system
- Check: The temperature in the nodes of the system using a thermal camera
- If the temperature: is more than 85°C, go to the next step
- If temperature: is between 60-85°C - check pressure and flow stability
- Check: System pressure using a pressure gauge
- If the pressure: is more than 120 bar, check the ventilation systems
- If the pressure: is within 80–120 bar — check the filtration
- Symptom: Incorrect filtering
- Check: The presence of impurities in the filters
- If: pollution is higher than 300 µm - remove the filter
- If: contamination is above 150 µm — perform cleaning
6. Matrix of accepted reasons
| Symptom | Probable reasons | Diagnostic testing | Expected result |
|---|---|---|---|
| Overheating of the hydraulic system |
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7. Analysis of root causes
7.1 Insufficient flow of working fluid
Insufficient flow of working fluid can occur due to restrictions in pipelines, lack of ventilation or clogging of filters. This leads to an increase in the temperature in the system. To confirm, measure the flow using a pressure gauge and determine if it is suitable for the operating conditions.
7.2 Insufficient cooling
Insufficient cooling can be caused by insufficient fan operation, contamination of the heat exchanger, or congestion in the cooling system. This leads to an increase in the temperature of the working fluid. To confirm, check the condition of the heat exchanger and ventilation.
7.3 Excess pressure
Overpressure can be caused by valve failure or lack of ventilation. This leads to an increase in temperature due to additional friction. Measure the pressure and check the valves to confirm.
7.4 Increased vibration
Increased vibration can be caused by pump failure, lack of balancing, or clogging. This leads to additional friction and increased temperature. Perform a vibration analysis to confirm.
8. Step-by-step repair procedure
8.1 Insufficient flow of working fluid
- Check the pipelines for blockages
- Replace or clean the filters
- Set the flow to 15 L/min
- Check pressure and temperature after correction
8.2 Insufficient cooling
- Check the condition of the fans
- Clean the heat exchanger
- Set the cooling flow to 10 L/min
- Check the temperature after correction
8.3 Excess pressure
- Check the valves for failure
- Set the pressure to 100 bar
- Check pressure after correction
8.4 Increased vibration
- Check the pumps for failure
- Set system balancing
- Check the vibration after the fix
9. Preventive measures
| The root cause | Prevention strategy | Monitoring method | Recommended interval |
|---|---|---|---|
| Insufficient flow | Periodic cleaning of pipelines | Flow measurement | monthly |
| Insufficient cooling | Periodic cleaning of the heat exchanger | Temperature measurement | monthly |
| Excessive pressure | Periodic inspection of valves | Pressure measurement | monthly |
| Increased vibration | Periodic balancing | Vibration analysis | monthly |
10. Replacement components and parts
| Description of the part | Specification | When to replace | UNITEC-D category |
|---|---|---|---|
| Hydraulic fluid filter | The minimum porosity is 300 µm | After 1000 hours of operation | Hydraulic drive |
| Heat exchanger | The minimum power is 10 kW | After 2000 hours of operation | Hydraulic drive |
| Pressure control valve | The minimum power is 100 bar | After 1500 hours of operation | Hydraulic drive |
| The pump is hydraulic | The minimum power is 5 kW | After 3000 hours of operation | Hydraulic drive |
Please contact for more details: https://www.unitecd.com/e-catalog/
11. Links
Documentation according to standards:
- DSTU 3024-95: Rules for technical operation of hydraulic systems
- EN 12743: Standards for hydraulic systems
- ISO 4401: Technical characteristics of hydraulic systems
- CE, UkrSEPRO: Certification of operation
Additional resources:
- Original documentation of the manufacturer
- UNITEC-D Maintenance Manuals
