When the breather valve filter element becomes clogged or fails, it can damage the hydraulic system through negative pressure cavitation and impurity intrusion. The specific impacts and quick diagnostic methods are as follows:
I. Three Types of Damage to Hydraulic Systems Caused by Filter Element Clogging/Failure
1. "Cavitation Failure" Caused by Negative Tank Pressure (Core Hazard of Clogging)
A clogged filter element prevents air from flowing smoothly into the tank. When the system cylinder retracts and the oil returns to the tank, negative pressure forms within the tank.
Direct Damage: Negative pressure causes cavitation at the suction end of the hydraulic pump, creating bubbles within the pump body. Over time, this can lead to wear of the pump blades and gears, causing abnormal noise and insufficient pressure. In severe cases, it can damage the pump seals, causing leakage.
Chain Reaction: Negative pressure can cause seals in areas such as the tank filler neck and sealing cap to fail, allowing unfiltered air to force its way in through gaps, accelerating oil contamination. 2. "Wear-Related Failures" Caused by Impurity Intrusion (Core Hazard of Failure)
When a filter element fails (e.g., damaged filter paper or loose seal), impurities such as dust, metal debris, and moisture can enter the tank directly, contaminating the hydraulic oil.
Component Wear: Impurities circulate with the oil and enter components such as hydraulic valves, cylinders, and motors, scratching the valve core sealing surfaces and cylinder walls. This can lead to valve blockage (stuttering), cylinder leakage (reduced thrust), and unstable motor speed.
Fluid Deterioration: Impurities accelerate hydraulic oil oxidation, forming sludge that clogs the filter element and orifices, further reducing the system's heat dissipation efficiency and causing abnormally high oil temperatures (over 65°C), creating a vicious cycle of "contamination-deterioration-more contamination."
3. "Leakage-Related Failures" Caused by Positive Tank Pressure (Secondary Hazard of Clogging)
If a filter element clogs and is accompanied by poor venting (e.g., a stuck check valve), positive pressure will build up in the tank when the system cylinder extends and fluid flows out of the tank. Direct Damage: Positive pressure can compress weak areas of the fuel tank (such as the fuel filler cap and welds), causing seals to deform, welds to crack, and fuel leakage. In severe cases, it can bulge the plastic tank, causing permanent deformation.

II. Four Practical Ways to Quickly Determine if a Filter Issue Is Present
1. Listen: Check for unusual intake sounds in the fuel tank.
Start the hydraulic system and repeatedly extend and retract the cylinder (simulating normal operating conditions). Listen for these sounds close to the fuel tank filler opening.
If you hear a "hissing" intake sound, the filter is clogged, preventing air from entering properly. The fuel tank is experiencing negative pressure, and the filter is most likely the problem. 2. Check: System pressure and operation for abnormalities
Observe the hydraulic system pressure gauge and actuator (cylinder/motor) operation:
Abnormal pressure: If the pump outlet pressure fluctuates significantly (e.g., the rated pressure is 16 MPa, but the actual pressure fluctuates between 12 and 16 MPa), and the pump itself has been ruled out, the filter element may be clogged, causing the pump to suffocate.
Abnormal operation: If the cylinder extension and retraction speed slows or freezes, or if the motor starts up with a delay, and the oil is not deteriorating, it is likely that the filter element has failed, causing impurities to clog the valve block.
3. Check: Filter element appearance and pressure differential
Disassemble and inspect the filter element: Open the breather valve, remove the filter element, and inspect it. If there is a large amount of dust or sludge attached to the surface, or if the filter paper is damaged or deformed, the filter element is clogged/failed.
Differential pressure test: If a differential pressure gauge is installed and the pressure differential is >0.15 MPa (refer to previous standards), the filter element is directly considered clogged and needs to be replaced immediately. 4. Test: Oil Cleanliness (Assisted Identification)
Use an oil cleanliness test strip or instrument to check the oil contamination level in the tank.
If the test strip shows obvious impurities (such as dense black specks), the oil hasn't been changed recently, and there are no other sources of contamination (such as seal leaks), it can be determined that the filter is failing and not blocking foreign matter.
If your system has experienced a similar problem, would you like me to create a hydraulic system filter troubleshooting flowchart? It includes steps from "Abnormal Symptoms" to "Locate the Filter Problem," helping you quickly distinguish between a filter problem and other component failures, avoiding blind repairs.