How to best maintain your hydraulic cylinders

Hydraulic cylinders are the essential parts that make your machine function. This blog will let you know how to best care for your cylinders, so that your machine continues to function optimally, you prevent breakdowns and your cylinders last as long as possible.

How exactly does a hydraulic cylinder work?

A hydraulic cylinder works based on Pascal's law. By pumping fluid, almost always hydraulic oil, into a cylinder under relatively low pressure, it pushes the piston outward. The pressure times the surface area of the piston determines the force. However, relatively low pressure does not mean that the pressure is actually low. Compared to the force that the cylinder can exert, the pressure may be low, but in reality the pressure in a cylinder is very high. This makes it all the more important to keep a cylinder in good condition.

Piston rods

First of all, you must ensure that the moving parts remain in good condition. The piston rod often moves in and out of the cylinder. Wear of the piston rod increases the risk of leaks and total failure of the cylinder. This can break and therefore damage many other, often expensive, mechanical parts.

Piston rods are made of different materials. For example, most piston rods are protected against corrosion by a chrome layer. However, this layer is porous and, especially in salty conditions, this can quickly lead to corrosion.

If you want to give your piston rods a longer life, it is better to look at piston rods made of stainless steel or rods with a ceramic or nickel layer. These are often a lot more expensive, but last much longer.

Maintenance tip for hydraulic piston rods:

Regularly inspect the cylinder rod in the fully extended position. Check whether you notice any corrosion and whether the surface is still smooth and lightly oiled. If the piston rod shows corrosion, pits, scratches or other damage, install a new piston rod. Avoid greater damage to, for example, the cylinder wall.

Hydraulic cylinder seals

In hydraulic cylinders you always have to deal with seals. This makes sense because you obviously want to keep the hydraulic oil in the cylinder and prevent leakage. Not only because of environmental damage, which can also cost you a lot of money due to downtime and cleaning, but also to ensure that the cylinder retains its operating power.

You come across different seals in cylinders. You have piston seals, rod seals, wipers and guide rings. All these parts play an important role in hydraulic cylinders, because they ensure that there are no leaks, no dirt enters the cylinder and the cylinder moves as intended.

Maintenance tip for hydraulic cylinder seals, wipers and guide rings:

You can visually inspect many of these sealing rings, but only when you take the cylinder apart. If you want to give a cylinder a good maintenance, replace all rings and seals at once. This prevents the cylinder from having to be taken apart more than once and with new parts you can be sure that you will not introduce dirt and contamination into the cylinder. If you order new parts, always make sure that they are resistant to the fluid in the cylinder.

Cylinder barrel, head and base

The cylinder barrel, head and base are easier to inspect than the internal parts. For hydraulic cylinders that have to withstand a lot, pay particular attention to the “inflation” of the cylinder wall. This is a sign that the cylinder has been operated under too high pressure too often and/or for too long. The wall then bulges and can burst under continuous high load.

In this case there is only one thing to do and that is to completely replace the barrel. This is an expensive affair, but for safety reasons it is the only correct option.

Maintenance tip for hydraulic cylinder barrel, head and base

Regularly inspect whether there are any deformations in the cylinder wall. If you do come across this, don't hesitate and replace it immediately. Prevent your machine from coming to a standstill, or even worse, from a dangerous situation because the cylinder can literally explode, causing the hydraulic oil to escape under high pressure. In the least serious case, you will have environmental damage and you will have to have it cleaned at your expense. In the worst case, it is a serious safety risk for yourself and bystanders.

Hydraulic oil

In the cylinder it is the hydraulic oil that ensures that the cylinder can do its work. Always make sure that the oil is in good condition and free of dirt. Therefore, check regularly whether the hydraulic oil is still in good condition. Drain some oil and see if the oil still has the right clear color. In every hydraulic system, no matter how well you maintain it, there is always some wear and tear.

Filtration is an important element to ensure that your oil remains in good condition. Replace your hydraulic filters on a regular basis and certainly when you replace the hydraulic oil. All impurities in your system should be in the filters, so by replacing the filters you remove a lot of dirt from the system.

Maintenance tip for hydraulic oil in cylinders

Perform regular inspections of the purity and condition of the hydraulic oil. A good rule for this is every 100 to 250 hours if you are working under high loads, such as with your larger excavators or shovels, and every 500 to 1000 hours if your machine is less exposed. As soon as you change the oil, immediately replace all filters in your hydraulic system. This ensures that you remove the collected impurities and pollution from your system.