Understanding the performance of your system
by Bruce Reader
August 9, 2017

Whether you are working with motor graders, skid steers, track loaders, backhoes or excavators, the one thing that each of these machines has in common is a hydraulic system. Think of them as wheeled or track “hydraulic platforms.”

From a maintenance perspective, hydraulic systems are often one of the most overlooked systems of a machine, yet they are arguably the most important when it comes to getting the best performance out of a piece of equipment. As best practices suggest, most operators will do a daily walkaround inspection, and as long as there are no leaks and the oil level is good, that is the end of it. But a hydraulic system requires much more work than that if you want to protect your investment and keep your equipment performing at its best. The following article focuses on three key elements of any hydraulic system: oil, filtration and system integrity.

1. Oil

A common goal today is lowering operating costs. Some contractors will take this concept the wrong way and use the cheapest hydraulic oil in order to keep costs down. This can save a few dollars in the short term, but it can also cause serious harm to your hydraulic system over time. Will you see a failure right away? No, but using the right kind of hydraulic oil can be the difference between an axial piston pump lasting 10,000 hours instead of 5,000 hours.

  • Manufacturer’s recommendations—Using the hydraulic oil listed in the operator’s manual will ensure that the system is performing the way that the engineers and product development team intended. Also, different regions require different types of oil. Running a hydraulic system in Arizona will require oil with a different viscosity than running a machine up in Canada, so be sure to look at the manual for cold and hot weather recommendations.
  • Additives—Hydraulic oil comes in a lot of varieties, and each has a different viscosity and additive package. The additive package that goes into the oil is designed to deal with specific types of hydraulic systems. For example, an excavator running at 5,000 psi has different characteristics and requirements than a machine running at 2,500 psi. Shear stability (an oil’s resistance to reduction in viscosity under mechanical stress), temperature and water resistance characteristics and all kinds of other considerations go into the hydraulic oil. Therefore, the specific needs of any hydraulic system determine the type of additives required. There is no one-size-fits-all solution. At a minimum, it is vital to change the hydraulic oil at the recommended intervals.
  • Storage and handling—The way you handle the hydraulic oil is just as important. Always make sure that it is kept in a sealed container in a dry area. Opening the container can potentially introduce contaminates into the oil—and it’s not just dust and particulate that you have to worry about. Moisture in the ambient air can have an adverse effect on hydraulic oil over time. You may not see any difference right away, but over time, the moisture can react with the different elements in the additive package and cause rust to form on spools, valves and other precision components of the system. This will cause poor performance and unnecessary long-term wear.

2. Filtration

One of the biggest mistakes in the field is neglect of the hydraulic oil filter. The way that most systems are designed, it can be a bit of a procedure getting to the filter, since it’s usually incorporated into the tank. A worn-out filter is obviously not going to perform as well as a new one, so it is important to follow the manufacturer-recommended intervals for filter replacement.

When replacing the filter, it is also important to use the filter recommended by the manufacturer. This component was chosen by the engineers and development team behind the machine to ensure that it is providing optimal performance, so any other filter, regardless of how similar it may look, is not going to perform as well and will allow contaminates into the system that will wear away at seals, spools and valves. All it takes is a small valve failure in a sophisticated hydraulic system to cause a million-dollar piece of equipment to quit running. Regardless of what type of machine you are using, no amount of quality and integrity can overcome poor maintenance.

3. System Integrity

We have talked about the basics of hydraulic oil and filtration, so let’s talk about the system as a whole. The following considerations are all things to keep in mind when looking at the overall health of a hydraulic system on a piece of equipment.

  • Death by a thousand leaks—We all know that a single weeping cylinder isn’t enough to justify pulling a machine off a jobsite. However, if leaks aren’t addressed, it will soon become one after another, and this will definitely have an impact on your machine’s performance. One thing to keep in mind is that every time you have a small leak, not only are you losing small amounts of oil from the system, but you are also allowing moisture and dirt to get into the system. These machines are operated in dusty conditions, and if there is a point where the system is compromised, that contaminate will inevitably find its way in. A leaking system operating with low oil and added contaminates not only causes more unnecessary wear on your filters and other components, but it also causes the machine to work harder, affecting operating temperatures and the overall performance of the machine.
  • Fluid sampling and analysis—This is another factor that is often overlooked. Many contractors will only take a fluid sample at the time of failure, but that doesn’t tell you anything. In order for fluid sampling to provide value, you have to do it consistently. If done on a regular basis, over time, your samples can give you an indication of problems that may be occurring and how they will affect you down the road. This way, you can handle things preemptively before a