The hydraulic valves are very essential to a smoothly running hydraulic system. If one fails, machines can no longer run, and that usually results in costly repairs and lost production time. No one would want to see that happen. Consistent upkeep and sharp eyes can thus prevent spending money and time in the future.
Here in this guidebook, we cover common warning indicators when a valve is on its way out, how to address those problems, and what to watch for with routine checks on a daily basis. If you take proper care of your valves, they’ll last you longer, and your equipment will run better with fewer shocks.
What is a hydraulic valve?
A hydraulic valve is essentially the core component regulating a hydraulic system. It manages the direction, pressure, and flow of how the fluid moves to enable machines to perform work. For instance, in an excavator: when extending and retracting a boom, that’s the valve in action. In an injection molding machine, when it opens and shuts smoothly, it’s again the valve that facilitates it. Due to that, the situation of hydraulic valves and their accuracy largely influences how efficiently and constantly the whole machine performs.
How to repair hydraulic valves when they malfunction?
Different types of hydraulic valves—such as ball hydraulic valves, hydraulic directional valves, and hydraulic control valves—are prone to malfunctions over extended periods of operation. While their structures and functions may vary, the types of failures they encounter are often quite similar. In the following section, we will examine the root causes of these common issues and outline practical solutions.
Sticking
This primarily manifests as the valve becoming stuck during operation, unable to move or change direction. This may occur when the spool is jammed by burrs. In such cases, disassembling the spool and removing the trapped debris will restore functionality.
Slow Movement
Occasionally, hydraulic valves may move extremely slowly. This is typically caused by contaminants like iron filings or dust entering the hydraulic fluid, creating friction during spool movement and hindering smooth valve switching.
If this occurs, immediately sample the oil to check for emulsification, darkening, or suspended particles to assess contamination levels. In cases of severe contamination, thoroughly clean all oil-contacting components and filters within the hydraulic system before replacing the oil with clean fluid. This will restore normal hydraulic function.
Hydraulic Oil Leakage
Hydraulic oil leakage is categorized into internal and external leaks. Leaks within valve bodies are often caused by corrosion and wear between valve components, excessive clearance, or aged seals, leading to fluid bypass and leakage.
Abnormal Pressure
If the hydraulic system’s relief valve trips frequently, inspect for abnormal pressure. Calibrate the pressure settings of relief valves and safety valves, while cleaning the reservoir and filter elements to ensure unobstructed oil flow.
Excessive Noise and Vibration
Significant noise and vibration in hydraulic systems are common issues typically related to pressure, flow rate, fluid quality, and mechanical components. The primary causes generally include the following three factors:
Insufficient Suction Flow to Hydraulic Pump
When the hydraulic pump receives inadequate suction flow, air bubbles form on the oil surface. This causes the pump to emit a “humming” or screeching noise during operation. Cleaning the suction filter screen or replacing the filter element will resolve this issue.
Internal Gear Pump Wear
After prolonged use, gear surfaces undergo material abrasion, increasing component clearance. This causes unstable oil delivery, inducing rapid fluid vibration within lines and valves, resulting in humming or screeching noises. Replacing the gear is the solution.
Hydraulic Valve Sticking
Hydraulic valve sticking also causes noise and vibration. Listen carefully for short, intermittent “clicking” or “thumping” sounds from the valve. If detected, this typically indicates sticking. Refer to the troubleshooting method described in the first point above to resolve it.
Excessive Temperature
Overheating hydraulic valves may stem from incompatible hydraulic fluid. When fluid viscosity is too high, increased flow resistance within the valve generates friction heat, causing temperature spikes. Address this by using manufacturer-recommended viscosity grades and performing regular fluid changes to maintain cleanliness.
How to Maintain Hydraulic Valves?
Hydraulic valves are the brain of every hydraulic system, which ensures equipment operates smoothly. Maintenance must be done regularly to prevent damage, minimize downtime, and prevent costly repairs.
Below are maintenance tips that are standard procedures for factory operation.
Selecting Appropriate Hydraulic Fluid
When purchasing hydraulic valves, always use the oil recommended by the supplier—this is not a profit-making recommendation. Any valve design requires specific viscosity grades; too high or too low viscosity will cause valve malfunction.
When blending oils with different base oils or additive systems, it is also not recommended. This will cause sedimentation, emulsification, or seal incompatibility and may result in blockage and premature aging.
Seal Maintenance and Replacement
Seals are not always the most outstanding components of a hydraulic valve, but their importance cannot ever be overestimated. When they leak, numerous parts are ruined, which significantly contributes to repair costs.
Rather than waiting for the seals to leak, I recommend keeping stock of various seal types usable with your hydraulic valves in your warehouse. These are essentially O-rings, lip seals, etc., which you can replace from time to time based on actual usage needs.
Maintain Optimal Temperature Range
Heat in excess during hydraulic system operation will shorten valves’ lifespan.
Maintaining the cooled oil temperature between 40-60°C lengthens valve life. But above 70-80°C, it speeds up oil oxidation and dramatically ages seals.
Curious about exact temperature limitations? These vary by seal material (NBR/FKM/PTFE) and oil type. Look to the valve manufacturer’s documentation for exact values.
During normal operation, adequate coolers at strategic points must be used to correct overheating. Operate at the rated fluid level of the tank to allow sufficient residence time and heat transfer surface to prevent excessive temperatures.
Valve Cleaning
Proper valve cleaning prevents failure caused by dust plugging. When cleaning is required, disassembly is permitted only after shutdown, pressure relief to full pressure, and lockout/tagout (LOTO) application.
Cleaning has to be carried out in a clean environment using seal-compatible cleaners and smooth tools to prevent scratching mating surfaces. On reassembly, follow the recommended torque values and sequence by the manufacturer. Bleed the system and carry out a low-load test run after installation to rule out any aberrations.
Maintenance of hydraulic valves is a continuous process rather than an event. Regular inspection and proper maintenance guarantee smooth operation, reduce unexpected downtime, and extend the service life of your hydraulic system to the maximum.
Conclusion
Hydraulic valves play a vital role in the efficient operation of any hydraulic system, and their condition directly impacts performance and lifespan. Proper maintenance and frequent servicing, and you can maintain costs under control and avoid unforeseen downtime. If you face any issues in practical application, please feel free to contact us—our technical advisors are ready to provide professional guidance.
