March 18, 2008 

'Inside Hydraulics' Newsletter

1. How to manage your boss
2. So you didn't think this was part of YOUR job description?
3. Pushing the hydraulic pressure envelope - again
4. Content for your web site or e-zine
5. Help us spread the word
6. Tell us what you think


How to manage your boss

A belated happy St Patrick's Day. Even considering my Irish heritage (my paternal grandfather was from Waterville in County Kerry) St Patrick's Day took on extra significance during my high-school years.

As a boarder at St Patrick's in Ballarat, it was an important date on the calendar - for obvious reasons. And one we all looked forward to. For it was the only day of the year when the food served at dinner was worth eating… even enjoyable.

Was I fortunate to have been sent to boarding school? Maybe. Maybe not. Certainly, it taught me to be self-reliant from a very young age. Some might say it was "character-building". Maybe it was. But there are other ways to build character in young men, and so I won't be sending my son to boarding school. His mother would never allow it anyway.

On the issue of self-reliance, one of our members wrote me this last week:

"Hey Brendan, I'm aching to get a copy of your new advanced hydraulics program ... I just have to convince my boss to pay for it."

Hmmm… ask not what you can do for yourself… ask what someone else can do for you. This is the polar opposite of self-reliance. With the possible exception of your parents, I think it's totally unrealistic to expect someone else to pay for your education. Nice if you can swing it - but unrealistic all the same. Particularly these days, given workforce mobility - which is magnified when there's a skills shortage - as is the case with hydraulics.

Some bosses are softer than others, but I gotta tell ya this type of approach wouldn't cut it with me. It just loses my respect.

But I'm not saying you shouldn't approach your boss for help - it's all about HOW you do it.

Consider this approach:

"Hey Boss, there's this new advanced hydraulics self-study course I'm keen to take - on my own time, and I was wondering if you'll pay for it initially and deduct X dollars per week from my wage over the next X weeks?"

As a fair-minded boss, not only would I agree to this, I'd also be willing to foot half the bill. Of course, I can't speak for your boss, but one thing I do know is, even if she's a tight wad and says no, you won't lose respect. Just the opposite - because you've demonstrated your willingness to learn, get ahead AND be self-reliant - character traits everyone admires and respects.

The Nice Things People Say …

"If more hydraulics users had this information - us manufacturers would have less problems!" Find out more ...

Phil Serre
International Director of Training

2.   So you didn't think this was part of YOUR job description?

In Insider Secrets to Hydraulics I discuss what it takes to become proficient at hydraulic troubleshooting. But there's another pre-requisite you won't find in the job description: the ability to educate and convince the most ardent sceptics - usually engineers with bugga all hydraulics knowledge. This story, sent to me by Joachim Renner, one of our members from Germany, is a great illustration:

Our company supplied eight double-acting cylinders for an auxiliary function on a tunnelling machine. The cylinders had the following dimensions:

Piston diameter 140 mm
Rod diameter 90 mm
Stroke 600 mm

During machine commissioning we got a complaint that none of the cylinders were holding pressure. All cylinders had been tested prior to delivery, and in spite of this it was plausible one cylinder had failed - but not all eight.

All the cylinders were removed and returned to us for debugging. Each was pressure tested first. And no defect was detected in any cylinder. So we sent the cylinders back to our client - with test reports.

After a couple of days I got a call from a very angry customer. All of the cylinders were still not tight!

What could I do?

I arranged to meet the client's technical people, on-site the following day.

During static testing for final acceptance, the cylinders kept failing. To demonstrate the problem, the cylinders were extended to the internal stop and pressurized to 250 bar. A decrease in static pressure could be observed on the cylinder circuit's pressure gauge. Eventually the pressure dropped to zero. All cylinders were fitted with pilot operated check valves at the cap-end port.

I asked for some technical background on the machine and was informed the designer had avoided using a separate pump circuit for this function by tapping the main circuit (350 bar operating pressure) with a 2 millimeter orifice and pressure reducing valve (250 bar). Hand-operated directional control valves were used for cylinder control.

The pressure required for unloaded cylinder extension was approximately 10 bar. I realized the pressure drop from 350 bar to approximately 20 bar was heating the oil being supplied to the cylinders. And this was the root of the problem.

To demonstrate the faultless function of the cylinders I installed a ball-valve and pressure gauge at the cap-end port of the cylinder - to eliminate all other control elements.

The cylinders were extended to the internal stop and pressurized to 250 bar. The ball valve was closed and the rod end port connection was removed. As the oil and cylinder body started cooling down, pressure decreased slowly to zero, although no leaking could be detected at the rod end port.

I explained to the engineers on site that the cause of their 'apparent' problem was the heating and subsequent cooling of the oil being supplied to the cylinders during testing.

But they still didn't believe me and remained of the view that the problem was a result of leaking seals.

So to prove the point, I got a hot-air gun - normally used to for packaging wrap and started to gently heat the cylinder. As I expected, cylinder pressure started to increase.

Seeing is believing… and at last the blind could see.

"Thanks for the great work on the two publications, Insider Secrets to Hydraulics and Preventing Hydraulic Failures. I have been in the hydraulics business for the past 20 years and it's very difficult to find any decent material on hydraulic maintenance, troubleshooting and failure analysis. These two books cover it all in easy to understand language... I conduct hydraulic training courses and plan to purchase copies to distribute to my students to share your practical approach to understanding a not so understandable subject."

Paul W. Craven, Certified Fluid Power Specialist
Motion Industries, Inc.

3.   Pushing the hydraulic pressure envelope - again

WARNING: The operating pressure of mobile hydraulic equipment is set to increase - again. For a detailed analysis of this forecast and what it means for hydraulic equipment reliability, read Brendan Casey's article in the January-February 2008 Issue of Machinery Lubrication magazine, available here.

To receive a complimentary subscription to this informative magazine (US and Canada only) go to:

4. Content for your web site or e-zine

Need some fresh content for your web site or e-zine? You now have permission to reprint these 'Inside Hydraulics' articles on your web site or in your e-zine, provided:

1. Each article is printed in its full form with no changes.

2. You send an e-mail to to advise us where you'll be publishing them.

3. You include the following acknowledgement at the end of each article:
About the Author: Brendan Casey has more than 17 years experience in the maintenance, repair and overhaul of mobile and industrial hydraulic equipment. For more information on reducing the operating cost and increasing the uptime of your hydraulic equipment, visit his web site:

5. Help us spread the word

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6. Tell us what you think

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