Maintenance Guide for Hydraulic Cylinders
Maintenance is the only way to prevent premature wear in hydraulic cylinders. Learn more about our recommended maintenance tasks.
Maintenance is the only way to prevent premature wear in hydraulic cylinders. Learn more about our recommended maintenance tasks.
A hydraulic cylinder with faults, such as worn seals or a scored rod, is a problem waiting to happen. When damaged, a hydraulic cylinder becomes less efficient, and worse of all, may move erratically and unpredictably, posing significant safety risks for technicians.
The good news is that through regular inspections, cleaning, adjustments, and other maintenance, these faults will develop more slowly (or not at all), ultimately helping you avoid breakdowns and premature replacements.
Disclaimer:
This article provides general advice on maintaining hydraulic cylinders. The operating environment heavily influences problems and wear rates. If your operating environment features abrasive dust, moisture, and temperature extremes, you should increase the frequency of certain tasks.
Always visually inspect the cylinder before powering up equipment for leaks and signs of wear. Never check for leaks with your bare hands—high-pressure, needle-thin jets of hydraulic fluid are extremely dangerous, and can even penetrate through gloves. Instead, wipe leak points with a cloth and note any excess hydraulic fluid.
During your visual inspections, note new rod scoring, cylinder swelling, or wear at the pivot pin, all of which indicate growing issues that need to be addressed sooner rather than later.
Fluid levels should always be normal—regularly check and remediate inadequate fluid levels. Lower levels can lead to overheating, which can expand components beyond their design limits, increasing wear and potentially leading to seal failure. Likewise, low fluid levels can reduce operating pressure and cause cavitation, which can damage the pump and allow metal particles to contaminate the hydraulic fluid. Lower levels also allow excessive air intake, which, like cavitation, can cause damaging metal-to-metal contact.
If your system has a gauge, check it daily to confirm the pressure is within the expected range. We also recommend logging daily readings to identify changes or trends in pressure, which can influence system performance.
If your system doesn’t have a built-in gauge, you can use a temporary one that screws into a cylinder port, control valve, or pump outlet.
Thorough cleaning of the exterior, especially the rod and wiper, helps reduce wear and prevent fluid contamination. It also makes it easier to see new problems as they emerge.
Use a clean microfiber cloth and an industrial degreaser when cleaning your cylinder. Never use abrasive cleaning solutions. If using compressed air, keep the jet away from the wiper, where it could force dirt into the seal.
Misalignment, which can result from damage and intensive wear, increases friction and loads on the cylinder and accelerates deterioration. The pivot pins (where the rod couples to the arm or device being moved) are particularly susceptible to misalignment. You can check for misalignments visually or with tools such as laser guides or straightedges. If you identify any alignment issues, you should address them immediately.
Leaks, rod scoring, slower performance, drift, and juddering often characterize damaged rod seals. However, worn or damaged piston seals aren’t truly visible until the cylinder is taken apart.
Any seal problems should be addressed quickly. Fortunately, you can easily purchase seal kits and replace them yourself. Cylinders vary widely, though, so always ensure you’re ordering the correct size. You can read this article for further guidance, and it never hurts to confirm details with your vendor before placing the order.
Dirty or contaminated hydraulic fluid reduces system efficiency and leads to rapid internal wear. Quality can be assessed by visual inspection or through more sophisticated testing.
Visual inspection involves looking for air bubbles, foam in the tank, and discoloration; the fluid should be the same clear/golden brown color. Brown or black fluid suggests overheating, while a milky or cloudy appearance indicates water. An abnormal odor indicates overheating or contamination.
More sophisticated testing ranges from filtration to detect particles to advanced laboratory testing. On high-value hydraulic equipment or where downtime is especially disruptive, consider installing fluid quality monitors or paying for regular external testing.
Degraded or contaminated hydraulic fluid should be replaced promptly. If particles are found, you may need to replace the seals or rebuild your cylinder, depending on the severity.
Check filters every six months. Many hydraulic systems have differential pressure monitors that signal increasing flow resistance and indicate when a filter needs to be replaced.
In systems without monitors, other indicators of filter problems are poor fluid quality and reduced system efficiency. Visual inspection for damage is also possible. However, many manufacturers and cylinder operators prefer to replace filters based either on calendar time or operating hours.
Wear and temperature changes can cause hydraulic systems to drift over time, leading to the cylinder moving at different speeds, with varying force, or to different positions than originally intended.
We recommend having a professional recalibrate your system to ensure it’s done correctly.
Fluid becomes contaminated over time, and the only way to correct it is through a system flush. These flushes should be done annually and are the only effective way to remove debris and replace dirty fluid.
To flush your system,
If more contamination shows up in the reservoir, repeat the process. When the system is clean, add new fluid and start up as recommended by the manufacturer.
Daily visual inspections are necessary, but they don’t replace professional system inspections. These comprehensive inspections should be performed at least once a year. During these inspections, all components are checked for wear, damaged components are replaced, and the cylinder is tested under load for performance issues.
Hydraulic cylinder systems can be hazardous when the right precautions aren’t taken.
Before any maintenance work is done, always depressurize the system as recommended by the manufacturer. Depressurization should be part of your facility’s LOTO procedures to avoid any unexpected movements.
Beyond depressurization, technicians should always wear safety glasses, goggles, or a full face mask, along with boots and gloves.
Refer to Best Safety Practices for Hydraulic Cylinders for more information.
As a cylinder wears, it may eventually reach a point where it needs more than just cleaning and inspection. If you’ve noticed any of these signs, schedule a professional evaluation:
You can read 5 Signs Your Hydraulic Cylinder Needs Immediate Repair and Repairing Versus Replacing Hydraulic Cylinders for additional information.
Founded in 1972, Yates Cylinders is an industry-leading cylinder manufacturer and repair and rebuild center in the United States. If your cylinder is underperforming, speak with our experts at Yates Industries. We can help you rebuild your existing cylinder, find a suitable replacement, or provide emergency repairs as needed. We specialize in repairing and rebuilding tie rod, welded, mill-duty, hydraulic, and pneumatic cylinders.
Visit our website to learn more about our capabilities, or contact us today to get started with an evaluation.
