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Fault Diagnosis and Troubleshooting of Hydraulic Valves in Wet Spraying Vehicles
Release time:
2026-03-11
Source:
Author:
Summary:
As the control core of the hydraulic system in wet spray vehicles, the operating status of hydraulic valves directly affects the performance of the equipment. Accurately diagnosing hydraulic valve failures requires a thorough understanding of the working principles and failure characteristics of various valve components.
I. Fault Diagnosis of Directional Control Valves
Fault characteristics of directional control valves
Common failure symptoms of solenoid directional control valves:
1. Spool Sticking: The actuator moves slowly or fails to move at all.
2. Electromagnetic coil burnout: The spool fails to shift, and the coil temperature is abnormal.
3. Increased internal leakage: System pressure cannot be maintained, and the actuator experiences self-settling.
4. Reset spring fatigue: Reversal is incomplete, and the response to movement is delayed.
Inspection method
On-site rapid diagnostic steps:
Measure the coil resistance (normal value) 20-30 Ω)
Check the control voltage ( 24VDC ± 10% )
Listen for the impact sound during commutation.
Observe the synchronicity of actuator movements.
II. Fault Diagnosis of Pressure Control Valves
Symptoms of a relief valve malfunction
Characteristics of abnormal stress regulation:
Pressure Fluctuations: Fatigue of the Main Relief Valve’s Adjustment Spring
Pressure cannot be built up: The pilot valve spool is stuck in the open position.
Excessive pressure: The valve spool is stuck in the closed position.
Abnormal Noise: Throttle Port in the Pilot Oil Circuit Blocked
Pressure Relief Valve Fault Identification
Signs of a malfunctioning decompression function:
1. Unstable outlet pressure: Oil contamination causes the spool to move sluggishly.
2. Pressure regulation failure: Damaged pressure-regulating spring or malfunctioning adjustment mechanism.
3. Increased internal leakage: The clearance between the spool and the valve body is too large.
4. Zero outlet pressure: The valve spool is stuck in the open position.
III. Fault Analysis of Flow Control Valves
Throttle Valve Fault Characteristics
Manifestations of abnormal flow regulation:
Unstable flow: Valve spool vibration or excessive oil temperature fluctuations.
Adjustment ineffective: Valve core stuck or adjustment mechanism damaged.
Actuator crawling: Flow pulsation caused by blockage of the throttling orifice.
System heating: Excessive throttling loss
Speed Control Valve Fault Diagnosis
Signs of speed control failure:
1. Unstable speed: The spool of the pressure relief valve or the spool of the throttle valve is stuck.
2. Speed control unavailable: The constant-difference pressure-reducing valve has failed.
3. The actuator is moving too fast: The throttle valve is stuck in the fully open position.
4. Too slow: Throttle valve stuck in the closed position.
IV. Fault Diagnosis of Cartridge Valves
Common Faults of Cartridge Valves
Fault characteristics of two-way cartridge valves:
Unable to start: The pilot control oil passage is blocked.
Poor sealing: Wear between the valve core and valve sleeve.
Opening and closing abnormality: Control cover plate damaged.
Internal leakage: Seal aging and failure
Checklist
Special Inspection of Cartridge Valves:
1. Measure the clearance between the valve spool and the valve sleeve.
2. Check the fluid flow path for unobstructedness.
3. Verify the pilot control function
4. Test the sealing performance
V. Fault Diagnosis of Proportional Valves
Electro-hydraulic proportional valve failure
Symptoms of abnormal proportional control:
Decreased control accuracy: Degradation of proportional solenoid performance
Slow response: Increased resistance to spool movement
Pressure and flow fluctuations: Sensor feedback is abnormal.
Complete failure: Electrical connection fault
Detection method
Specialized testing for proportional valves:
Detect the electromagnet's current - Force characteristics
Test the spool displacement sensor
Analyze the control signal waveform
Measure the valve internal leakage.
VI. Systematic Diagnosis of Faults
Diagnostic Process
Systematic Troubleshooting Steps:
1. Observe the fault phenomenon and record any abnormal behaviors.
2. Analyze the hydraulic principles and identify the relevant valve groups.
3. Perform functional testing to verify the judgment results.
4. Disassemble, inspect, and confirm; develop a repair plan.
Detection tool
Essential testing instruments:
Digital Multimeter: Measurement of Electrical Parameters
Pressure gauge: System pressure monitoring
Flow meter: Flow characteristic testing
Oscilloscope: Signal Waveform Analysis
VII. Preventive Maintenance Measures
Daily maintenance
Key points for preventive maintenance:
Maintain oil cleanliness ( NAS 8 Within the grade)
Regularly check the fastening condition of the valve assembly.
Operating temperature of the monitoring system
Record the operating status of valve components.
Regular maintenance
Planned Maintenance Content:
1. Inspect the sealing performance of valve assemblies every quarter.
2. Measure the resistance of the solenoid coil every six months.
3. Perform valve group performance testing annually.
4. Establish a record archive for valve replacement.
Conclusion
Fault diagnosis of hydraulic valves requires a systematic analysis that combines the equipment’s operating principles with its actual performance. By establishing a standardized diagnostic procedure, equipping with necessary testing tools, and enhancing maintenance personnel training, we can quickly and accurately identify the root causes of failures. It is recommended to develop detailed maintenance procedures for valve components, establish comprehensive equipment records, and conduct regular preventive maintenance to ensure that the hydraulic system remains in optimal working condition at all times, thereby providing strong assurance for the reliable operation of the equipment.
RELATED INFORMATION
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Address: Jinrong Tongxin International Industrial Park, Changsha High-tech Zone
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Telephone:400-186-0868
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