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Predictive Hydraulics Maintenance ben lee

Predictive Hydraulics Maintenance Can Save You Time and Trouble 

We’ve always been a fan of predictive maintenance for hydraulic systems. It can save time, system damage, expense and downtime. If it’s not already embedded into your workshop processes, then we recommend that predictive maintenance is put right in there along with your inspection processes.

In this post we look at the categories that John Moubray uses in his Reliability Centred Maintenance II book to understand how predictive reasoning should be approached. This is then followed by an example of how it could be used to understand what’s happening with your hydraulic system by using your powers of reasoning.

Broken into these 6 major categories, these maintenance actions can save you expense, time and of course loss of productivity through downtime. What any engineer who works with hydraulic systems should focus on are:

1. Dynamic effects including the monitoring of vibration, pulses and acoustic emissions.

2. Particle effects including the monitoring of particles in the operating environments of the component – ie the condition of the lubricant.

3. Chemical effects: monitoring of the chemical elements in the components operating

4. Physical effects such as cracks, wear, fatigue

5. Effect of temperature

6. Effects of electrical


Although Moubray’s list does cover most of the hydraulic systems maintenance needs, it does not cover all and there are new techniques being discovered and devised continually that should be researched. The visual inspection is one of the most basic and necessary of all predictive maintenance techniques.

Putting this to the forefront, it’s important to look for the following during a hydraulic system inspection:


·         Both the quantity and the quality of the hydraulic oil in the tank needs to be checked. The appearance should be bright and clear.

·         Check for any leaks or weeps around the seals, connectors and component bodies.

·         The surface condition of the tubes, pipes and hoses external.

·         The cylinder rod-wiper seal condition needs to be checked.

·         The cylinder rod surface. Look for scores, nicks and dents.

·         The filter clogging indicator position.

·         The readings of the operating pressure (test-points and gauges that have been permanently installed should be used)

·         The operating temperature of oil (use either an installed thermocouple or a heat gun)

·         Listen out for abnormal noises such as knocking and clicking


The success of predictive maintenance tasks depends on whether data is recorded and then how it is analysed, whether it’s collected through human senses or by using sophisticated measuring tools. It is then necessary to take actions that will either remedy the situation or avoid damage from occurring.  The process for predictive maintenance is this:

·         Inspection

·         Data collection

·         Analysis of data

·         Predictive reasoning to ascertain possible future issues if maintenance is not addressed


As an example, you may prefer to perform an inspection of your system as part of your regular maintenance routine. You may discover that there is a noise that has increased in volume and that there is no longer a smooth cylinder movement with your actuator. There could be an interpretation of this even as there being issues with reliability and performance of the system up ahead including issues with lubricity. These are all issues to record and take note of for future analysis.

In addition it’s necessary to ensure that the interpretation of the data is in the right context. Perhaps your visual inspection reveals an issue with the filter being clogged. You may identify this from the clogging indicator. Although this would not normally be an issue, it is if the last time the filter element was cleaned or changed was just the day before. Although the data is the same, used through the filter of a different context, then your reasoning will be entirely different.

Summary. It’s important to identify issues in hydraulic systems so that action can be taken whilst the issue is still small. Predictive engineering offers this solution. It also makes it possible to refine your system so that you can avoid issues and enable your machine to have less downtime and expense. It’s truly worth getting into the routine of looking for issues early on.

Our engineers are focused on producing mobile hydraulic power packs. We provide insights into hydraulic system maintenance for those who have an interest. If you’re looking for a custom solution to your hydraulic system application needs, contact us today. 

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