Invest in Proactive Maintenance for Your Hydraulic Equipment

Brendan Casey

I recently purchased a used SUV with the plan to do some traveling with the family. It’s a big trip, starting with a journey across the Nullarbor Plain from the west to east coast of Australia. If you spend 12 hours a day in the car driving, you can cover the distance in four days.

However, the Nullarbor is a desolate place. There’s not much out there. You’re lucky if you see a kangaroo or emu between gas stations, and they’re hundreds of miles apart. It’s certainly not somewhere you want to break down. This would be even more unacceptable for me, being a preventive maintenance guy and knowing if something goes wrong with the vehicle that I’m really going to hear about it from my wife.

To minimize the possibility of any nasty (and embarrassing) surprises in the middle of the desert, I took my newly acquired but pre-loved SUV down to the automobile association for a thorough workshop inspection. I dropped it off in the morning, and when I arrived to collect it later that day, I could see it was still up on the hoist.

3 Steps Toward Proactive Maintenance


1. Set Cleanliness Targets
Target cleanliness level should reflect reliability goals.




2. Take Specific Actions to Achieve Targets

  1. Reduce ingression
  2. Improve filtration




3. Measure Contaminant Levels Frequently

  1. What gets measured gets done (Step 2)
  2. Post control charts of measured results


I knew all was not well when the inspecting mechanic invited me out into the workshop. When we got underneath the vehicle, the first thing he pointed to was a broken front differential mount. While I’m thinking to myself, “Wow, that’s not very cool,” he shows me a lower front ball joint that’s shot. Strike two. Now I’m thinking, “Enough already.” Thankfully, there was no strike three.

Of course, the ideal outcome from any maintenance inspection or predictive maintenance task is to find nothing wrong. On the other hand, the discovery of a fault, defect or other cause for alarm vindicates performance of the task. It essentially turns what could otherwise be classified as an expense into an investment. It’s kind of bittersweet.

The dictionary defines expense as a loss for the sake of something gained. Investment is defined as property or other possession acquired for future financial return or benefit.


95% of Lube-Tips subscribers view proactive maintenance as an investment.


Since the above issues are not the sort of problems you can fix on the side of the road with only a fistful of ring spanners, ignorance is not bliss. Based on the proverbial truth that a stitch in time saves nine, the $185 it cost to have my SUV inspected means that it was, by definition, an investment. Early detection undoubtedly saved me many hundreds, perhaps even thousands of dollars, and that’s without considering the likely stress and inconvenience a breakdown in the middle of nowhere would have caused.

This leads to another point, which is what you do by way of preventative and predictive maintenance is largely determined by the cost and consequences of failure. Being about to embark on a transcontinental road trip raised the stakes. Had I not been, I wouldn’t have bothered having my SUV inspected. Yet it still would have been a sound investment.

Notwithstanding the premise that a dollar spent on PM/PdM should always come back with friends attached, the bottom line is the more you know about the operational condition of your machines the better, especially when this intelligence can be acquired cheaply.

In the case of hydraulic machines, a lot of useful predictive data can be gathered with minimal outlay. Pressure, temperature and speed (flow) are three revealing vital signs of every hydraulic machine that are easy and cheap to monitor.

From a reliability perspective, operating pressure is load (and load influences wear) on the system’s components. Pressure, of course, is easy to monitor with the appropriate installation of pressure gauges or transducers.

Output speed is diminished by internal leakage, a variable influenced by oil temperature (viscosity) and wear. Speed, or early detection of the loss of it, is easily achieved using a stopwatch to record machine cycle times.

The operating oil temperature and thus viscosity influence component lubrication, and when temperature is monitored from an established baseline, it can provide early warning of loss of efficiency resulting from an increase in component wear or damage. The operating oil temperature of a hydraulic machine is easily monitored using an infrared thermometer (heat gun) or by the installation of appropriate instrumentation.

In terms of tracking and compiling this data, it’s a good idea to take readings on the hottest and coldest days of the year as well as on a couple of average temperature days in between. This provides a baseline of information. In addition, taking readings at regular intervals - each day or shift, for example - can provide early warning of impending problems. If the system starts to have trouble, taking a set of readings will reveal if it’s operating outside its normal parameters.

Beyond this, your mission is to determine what you should be doing by way of proactive maintenance for the hydraulic equipment you own or are responsible for and to make sure it’s all up to date.

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About the Author

Brendan Casey has more than 20 years experience in the maintenance, repair and overhaul of mobile and industrial equipment. For more information on reducing the operating cost and increasing the...