What are the common faults of hydraulic pumps and how to deal with them?

The hydraulic pump, the heart of the hydraulic system, is a critical component that converts mechanical energy into hydraulic energy. Its performance directly impacts the efficiency and reliability of the hydraulic system. However, over time, hydraulic pumps are inevitably prone to various faults, leading to problems such as insufficient system pressure, abnormal noise, and leakage. In severe cases, these problems can even cause equipment downtime. Prompt and accurate diagnosis and treatment of hydraulic pump faults are crucial for ensuring stable equipment operation. This article will examine common hydraulic pump fault types, thoroughly analyze their causes, and propose scientific troubleshooting and repair methods.

Common Hydraulic Pump Failure Types
Hydraulic pump failures can be broadly categorized as follows:
Insufficient or unstable pressure
Insufficient output flow
Abnormal noise and vibration
Leakage
Overheating
Mechanical wear and damage

Insufficient or unstable pressure
Failure symptoms
The hydraulic system pressure fails to reach the set value, resulting in sluggish or weak actuator movement.
Severe pressure fluctuations and unstable system operation.
Possible causes
Internal leakage in the hydraulic pump
Worn internal pump components or seal failure can cause oil to flow back from the high-pressure chamber to the low-pressure chamber, reducing output pressure.
Damage to the pump body or valve
Cracks in the pump body or a broken control valve spring affect pressure regulation.
Clogged or leaking system piping
Increased oil line resistance or system leaks prevent pressure from being maintained.
Abnormal hydraulic oil viscosity or contamination
The oil is too thin or contains impurities, reducing pump efficiency.
Insufficient drive motor power or abnormal speed
Insufficient motor speed causes a drop in pump output pressure.
Solution
Inspect and replace severely worn seals, bearings, and vanes.
Inspect the pump body and control valve, and repair or replace damaged parts.
Clean or replace the oil filter to ensure unobstructed oil flow.
Use standard hydraulic oil and change the oil regularly.
Inspect the drive motor to ensure normal speed and power.

Insufficient output flow
Symptoms
Actuator movement speed slows down, resulting in insufficient flow supply.
The hydraulic pump output flow is lower than the designed value.
Possible Causes
Internal wear of the hydraulic pump
Wear in the rotor, vanes, gears, and other components increases clearances, leading to internal leakage. Blockage or leakage in the suction line
Blockage or leakage in the suction line results in insufficient pump suction.
Hydraulic oil temperature is too high.
Lower oil viscosity reduces pump suction performance.
Improper hydraulic pump assembly clearance.
Insufficient assembly precision leads to increased internal leakage.
Remedy:
Inspect the pump's internal components and replace worn parts.
Inspect the suction line to eliminate blockages and leaks.
Control the hydraulic oil temperature and install a cooling system.
Perform proper assembly and adjustment according to technical specifications.

Abnormal Noise and Vibration
Symptoms:
The hydraulic pump makes loud noises during operation.
Significant vibration in the pump body or connections.
Possible Causes:
Cavitation:
Bubbles form at the hydraulic pump's suction port, causing the hydraulic oil to vaporize within the pump body, generating cavitation noise.
Worn or loose bearings:
Damaged or loosely installed bearings cause vibration and abnormal noise.
Improper suction line design:
The suction line is too long, bent, or the suction filter is clogged, resulting in poor pump suction. Hydraulic oil viscosity is too high or severely contaminated.
Oil flow is poor, causing noise.
Abnormal hydraulic pump assembly clearances.
Excessive or uneven clearances between parts cause vibration.
Solution:
Inspect the oil suction system and optimize the piping design to ensure smooth oil suction.
Replace damaged bearings and adjust assembly tightness.
Clean or replace the oil filter to ensure oil cleanliness.
Control oil viscosity and temperature and use qualified oil.
Precisely assemble the hydraulic pump to ensure clearances meet requirements.

Leakage Symptoms:
Fault symptoms:
The hydraulic pump oil seal is leaking, with oil leaking from the pump body or shaft seal.
Insufficient oil pressure in the system affects pressure stability.
Possible causes:
Aging or damage of seals.
Oil seals, O-rings, and other seals may be worn or deformed, resulting in loss of sealing effectiveness.
Improper installation:
Seals installed incorrectly or damaged, leading to leakage.
Excessive clearance between the pump shaft and seal.
Weakened sealing effectiveness, making leakage more likely. Pump body damage
Cracks or surface damage on the pump body can cause oil leakage.
Solution
Regularly inspect and replace seals, using quality sealing materials.
Install seals strictly according to specifications to avoid damage.
Adjust the clearance between the pump shaft and the seal to ensure sealing performance.
Inspect the pump body for integrity; repair or replace any damage promptly.

Overheating
Symptoms
The hydraulic pump is operating at too high a temperature, exceeding the normal oil temperature range.
The system is experiencing oil degradation and poor oil quality.
Possible Causes
The hydraulic system is overloaded.
Excessive overload operation can cause the hydraulic pump to generate excessive heat.
Faulty or missing cooling system
Cooler blockage or fan failure can lead to poor heat dissipation.
Degraded hydraulic oil quality
Aging or increased impurities in the oil can reduce heat dissipation performance.
Increased internal friction in the hydraulic pump
Severe wear or insufficient lubrication can increase frictional heat generation.
Solution
Avoid overloading and schedule operating cycles appropriately.
Inspect the cooling system, clean the cooler, and repair the fan. Replace the hydraulic oil regularly to keep it clean.
Maintain hydraulic pump lubrication and replace worn parts promptly.

Mechanical Wear and Damage
Fault Symptoms
Severe wear and degradation of hydraulic pump internal parts.
Unusual noises and mechanical operation are present.
Possible Causes
Hydraulic oil contamination
Impurities have entered the hydraulic pump, causing increased wear on components.
Insufficient lubrication
Insufficient oil supply or substandard lubricant quality.
Insufficient installation precision
Assembly errors lead to poor meshing of parts.
Long-term overload operation
Excessive wear causes component damage.
Solutions
Keep the hydraulic oil clean and replace the filter element and oil regularly.
Ensure the normal operation of the lubrication system.
Strictly follow technical specifications for installation and commissioning.
Use equipment appropriately and avoid overloading.

Hydraulic Pump Troubleshooting Techniques
Observe operating status
Preliminarily determine the nature of the fault by listening to the sound, observing the oil flow, and measuring temperature.
Measure pressure and flow
Use a pressure gauge and flow meter to verify that the design requirements are met. Check the oil condition.
Test the oil's cleanliness, viscosity, and temperature to eliminate oil quality issues.
Disassemble and inspect the hydraulic pump.
If necessary, disassemble the pump to inspect component wear and seals.
Troubleshoot pipeline and filter issues.
Confirm that the pipelines are unobstructed and the filter element is unblocked.

Daily Maintenance Recommendations for Hydraulic Pumps
Regularly replace the hydraulic oil and filter element to ensure oil cleanliness.
Check the hydraulic pump's mounting fasteners to prevent loosening.
Regularly check the pump's temperature and pressure to detect abnormalities promptly.
Perform proper equipment lubrication and seal maintenance to extend its life.
Keep the suction line clear and airtight to prevent cavitation.
Create fault records and maintenance records to facilitate analysis and prevention.

Conclusion: As a key component of a hydraulic system, the performance and reliability of the hydraulic pump directly impact the overall operation of the equipment. This article details common hydraulic pump failures and their causes, and provides targeted solutions and maintenance recommendations. Only by strengthening daily management and scientific maintenance of hydraulic pumps can we effectively prevent failures, extend equipment life, and ensure the stable and efficient operation of the hydraulic system.