Lubrication is an essential part of a hydraulic system's maintenance regime. However, it is often not fully appreciated that the majority of hydraulics that are used these days operate with planned leaks. Hydraulic systems manufacturers allow for an acceptable amount of lubrication to leak under normal operating conditions. Therefore, it can be tricky for operators to determine whether a leaking hydraulic cylinder is normal or requires attention. If in doubt, contact a reputable hydraulic cylinder services company, but this guide should allow you to work out whether you are facing one of the common problems.
If you can see the lubricant of a hydraulic cylinder running on the outside or have detected a pool of lubricating material which must have been dripping away, then it is certainly likely that the cylinder requires attention. This is because the planned-for leakage of lubricant within a hydraulics system is usually not possible to see. Internal leakage of lubricating fluid allows it to flow from highly pressurised parts of the device to lower pressurised sections. Under normal operation, this usually means it remains inside and does not leave the sealed hydraulic circuit. Therefore, visible leakage is a good indication that a hydraulic cylinder repair is required.
Diagnosing a Leaky Cylinder
Because lubricant can exit a hydraulic system for a number of reasons, there is no single repair that you can do to ensure that the problem goes away. The most commonly seen cause of severe internal leakage, which will often result in lubricant discharging, is from wear of the system's component surfaces. This sort of leakage can result from poor system design in the first place meaning the entire cylinder may need replacing. In other cases, incorrect component selection or low-quality control tolerances may be the root of the problem. Because of the diagnostic problems with leaky cylinders, it is better to identify potential problems at an early stage by regularly monitoring system performance and reliability. Keep an eye on any increased operating temperatures that are detected because these are usually the first indication of excessive internal leakage.
Low Fluid Viscosity
In some cases, the hydraulic system itself is fine, and it is the lubricant which is the cause of operational problems. Although non-planned for internal leakage can lessen system performance on its own, the problem will often get worse if the lubricant's viscosity also decreases, as a result of such leaks. With a decrease in the fluid film strength—which can result from internal leaks—as well as using the wrong sort of lubricant, the undesirable result is often the premature wear of hydraulic components.