Hydraulic cylinders are often used in civil engineering, construction and manufacturing. They are actuators used to provide a powerful linear mechanical force, making them suitable for manufacturing equipment like hydraulic presses, injection moulds and compactors. Additionally, they can be used in dozers, excavators, dump trucks and other vehicles that require a unidirectional motion.
Using pressurised hydraulic fluid, hydraulic cylinders move a piston rod back and forth through a cylinder barrel. The cylinder is sealed at both ends, at the base and at the cap through which the piston rod sticks out.
For single action pistons, the hydraulic fluid enters only from the base side via the branch pipe. This pressurised fluid creates a force that pushes the piston rod out. An integrated spring then pushes the piston back to its original place, thus retracting the rod.
For double action cylinders, the fluid enters from the base side once again, pushing the piston rod out. Hydraulic fluid then enters the opposite side (at the cap), which pushes the piston back to its original place and retracts the rod.
With so many working parts, it can be difficult to maintain your hydraulic system. To ensure that it’s working properly, it’s important to take the time to address your hydraulic cylinder’s maintenance needs.
When it comes to hydraulic system maintenance, there are few things to look out for. To help you, here’s a general guide on how to maintain your hydraulic cylinders.
Inspect the cylinders
You should regularly check for visible damage on your cylinders. The main things to look out for are uneven wear on the rod bearings and corrosion.
If you see uneven wear on the bearings, it is usually a sign of a misaligned rod. The rod bearings are installed in the cylinder to minimise the amount of metal-on-metal contact (i.e. between the rod and the cap). It also limits side loading and pressure spikes.
If you’re noticing one part of the bearing starting to wear down faster than other areas, it is most likely due to side loading. This is when an external force or mass moves the piston rod outside of its unidirectional route. This movement will lead to uneven wear on the bearings and could potentially cause the rod to bend. If there’s uneven wear on your bearings, check for external forces or mass could be affecting the route of the piston rod.
If there’s corrosion, it’s most likely a sign of too much moisture entering the hydraulic cylinder. If the corrosion is minor, it’s possible to repair the rod through re-chroming or re-polishing. However, if the internal corrosion is too severe, the affected parts will have to be replaced.
To prevent this, ensure that your seals are working properly. Faulty seals and filters will allow water and other contaminants to enter the cylinder barrel and cause damage.
Additionally, corrosion could also occur in cylinders that are being used in unsuitable environments. This includes settings that are prone to moisture. Thus, it’s important to know the various settings that you’ll be using your hydraulic system in. Be aware of the weather conditions as well temperature levels.
If your hydraulic system needs to be operating for a long period of time, it’s a good idea to keep spare cylinders. This will allow you to rotate the cylinders on a regular basis and maintain the ones that aren’t in use.
These out-of-use cylinders can be taken apart if necessary. This is a good opportunity to replace the seals and check the condition of the rod, piston and cap.
Inspecting the insides of your cylinders can give you a good indication of your hydraulic system’s overall condition. For example, if varnish is forming on the rod, it is a sign that your oil is running at an excessively high temperature. Additionally, if you notice pitting and other blemishes on your piston rod, it is likely that a loose piece of metal has been bouncing around your hydraulic system.
Having a spare set of cylinders means you can continue working while at the same time maintaining the condition of your hydraulic system.
Keep the hydraulic oil clean
Most hydraulic cylinder failures are caused by dirty oil. Unclean hydraulic fluid is the result of too many contaminants entering the cylinder barrel. Contamination particles in the fluid will create excessive friction, which can then damage your hydraulic system. Consequently, damaged rods, seals and caps will lead to even more contaminants entering the cylinder.
To prevent this from happening, make sure you’re using high-efficiency filters in your hydraulic cylinders. These filters will remove contamination particles and ensure that the oil is clean when it enters the barrel. You can also get a pop-up indicator that notifies you when your filters are clogged. This will allow you to replace them before unfiltered and contaminated hydraulic fluid enters the cylinder.
Check your lube oil system
Your lube oil system helps your cylinder avoid excessive friction. If this is not working properly, the friction can cause damage to your hydraulic cylinders and its parts.
To check if your lubrication system is working properly, make sure that your reservoir has enough lube oil in it. Once you’ve checked that, you need to make sure that the oil line isn’t clogged.
To do this, you will need to connect a blow gun to the line and see if it expels oil. If it does, then your lubricator is working properly. If there isn’t, then your oil line is clogged. In some cases, you can simply repair the line by finding a way to unclog it. However, if this is not possible, you will have to replace the entire thing.
Additionally, too much oil in the reservoir can also cause damage. Excessive oil will cause hydrolock and prevent the cylinder from moving properly.
As you can tell, hydraulic cylinders do a lot of work. It’s important to keep an eye on function and condition in order to make sure your machinery runs as smoothly as possible. Before going into repairs, ensure that you know exactly what the cause of the issue is. You might find yourself replacing a part only to find out that the source of the issue lies somewhere else. If you’re unsure of anything, make sure to contact a hydraulic cylinder specialist.