How to maintenance hydraulic cylinder?

Many hydraulic failures occur because of hydraulic oil contamination. This is important to prevent damage to your system and components. If hydraulic oil is contaminated, it must be thoroughly cleaned as soon as any contamination has been found. It is also best to fit high-efficiency filters and change them when necessary.

If a filter has a build-up of debris, a differential pressure gauge can be installed to give you a good indication as to when they need to be changed. This means that you will be preventing a bypass, where the oil flows through the system unfiltered.

Regular maintenance on your hydraulic cylinder is important for optimal performance. Make sure you keep a close eye on the condition of the cylinder rod for any signs of corrosion, pitting or wear. Too much moisture can cause corrosion; whether this is from the air or from within the hydraulic fluid itself. If water contamination occurs within the fluid, it can cause major failure of the component or system - the oil therefore needs to be thoroughly cleaned as soon as possible. Corrosion also encourages wearing of the seals, due to increased friction; pitting causes a similar problem.

Misalignment is often the main cause of uneven wear within a cylinder. Premature wearing of the bearing seals and rod can be caused by side loads allowing the rod to rub on one side of the bearing. Hydraulic cylinder maintenance here can often be as simple as a re-chrome or polish to repair a corroded or damaged rod. If a cylinder rod is beyond repair, a replacement is the best course of action. However, before you re-install the new rod, it is important to first remove the problem that originally caused the damage and make the new cylinder more cost-effective.

As with other hydraulic components, if the risk of downtime is not an option, it is always a good idea to hold another cylinder(s) either as a ‘critical spare’ (see below) or that you can alternate usage between regularly. This break between uses keeps the cylinders in good shape, despite possible particle contamination and harsh operating conditions. It is also wise to undertake maintenance on these cylinders when they are removed from the system, so that they can be repaired if necessary.

Before re-assembling a cylinder, you may want to first replace all of the seals. Inspection of the cylinders may also give you an idea as to the condition of the entire system. For example, if there is a consistent varnish throughout your system, it could mean that the oil temperature is too high and it needs to be altered.

Each separate part that makes up your hydraulic cylinder is just as important as the cylinder itself. For example, if a pivot pin or clevis is worn or damaged, this could cause slop and play within the joints of the cylinder. This leads to misalignment and wear or more permanent damage.

*Critical spares analysis -- an analysis of system critical hydraulic components and recommended spares; so that you can understand which of your hydraulic components are most susceptible to failure and the impact that this may have on safety, production and systems performance… and just as importantly the cost and lead times involved in sourcing replacements.