July 7, 2009 

'Inside Hydraulics' Newsletter

1. It's never too late to start
2. Why following the majority can be dangerous
3. How to consolidate your hydraulic oil inventory
4. Content for your web site or e-zine
5. Help us spread the word
6. Tell us what you think


It's never too late to start

Last Sunday I had a ten-minute telephone conversation with an old friend of my mom's. Ken is 80 and has just been diagnosed with prostate cancer. For him, the prognosis is about as good as it gets. The cancer was detected early and there is no sign of its spread. Plus his attitude is nothing but positive.

During our conversation he told me he was cutting back on some of his volunteer work because he wanted to make some time to do a couple things he'd been wanting to do for a while: learn Latin and calculus. At 80. For Ken, 'learn' means teaching himself from books.

I've known Ken for many years and whenever I talk to him - about anything from electronics to cancer treatment, I learn something. So when he mentioned he was also busy re-cataloguing some of the 1500 books he owns, I wasn't the slightest bit surprised.

To this I remarked, that far too many people these days have small libraries and big TVs - something you've no doubt heard me say before. Ken's response was to tell me this story:

He was in his local supermarket during the school holidays. When he got to the checkout, he started chatting to the operator - a teenage boy. In an effort to make small talk, Ken asked the lad if he was enjoying his holidays. To which the young man replied he was bored.

Ken responded by inquiring, in a pleasant way: "What are you reading at the moment?"

The young man looked at Ken as though he was stupid and snapped back: "I don't read."

Clearly, there's much more than a couple of generations separating these two men. When I thought about it afterwards, I found myself wondering where that young man will end up in life. Hard to say of course, because it is never too late to start. Reading that is, or to learn Latin, calculus or anything else.

I have to confess to not reading much during my formative years; only reading what I had to. But I'm making up for it now. And if I'm fortunate enough to make it to 80, like Ken, I hope I still have a healthy thirst for knowledge.

The Nice Things People Say ...

"The knowledge I've gained from this information has been so valuable it has earned me a raise!" Find out more ...

Jack Bergstrom
Heavy Equipment Mechanic
Sharpe Equipment

2.   Why following the majority can be dangerous

So what am I reading at the moment? Well, I just finished Moneyball by Michael Lewis. The subject of the book is American baseball. I'm not a baseball fan and know very little about the sport - although I now know more than I did. But that's not why I read it.

When it was first published, Moneyball created a big stir in baseball circles because it challenged the status quo. In the Afterword, the author remarks on the fact that some of the most ardent critics of his book from within baseball circles hadn't even bothered to read it. As someone who's written a book considered by many to be controversial, this is something I can definitely relate to.

Moneyball is about many things other than professional baseball. But the overarching ones is: be wary of the majority. Just because the majority does something a certain way, it doesn't mean it is correct - or the best or most efficient way of doing things.

I can tie this 'majority-is-wrong' principle to more than a few issues in hydraulics. One that comes to mind, and which won't be new to you unless you've recently joined this forum, is the use of pump suction strainers.

I'm not a fan of suction strainers and actively campaign against their use. But as the author of Moneyball found out, when you take a position against the majority, there will by many who disagree with you. And so I regularly hear from folk who feel they need to explain to me why their hydraulic system is different and why they have no alternative but to use this pump-killing device. This one is typical:

"I disagree with your position on suction strainers. On our machines we have up to 6 pumps fed from a manifold. All have suction strainers fitted. When a pump expires it sends metal everywhere as well as into the intake manifold. These strainers catch the big lumps and stop it being sucked into the next pump. So if these strainers were omitted in our situation it could get very costly as there'd be several pumps to replace instead of one."

There are a few possible exceptions to the rule of NOT using suction strainers, but this isn't one of them. This member didn't send me a diagram of the pump and manifold arrangement, but if suction strainers are necessary for the reasons he states, then it is only due to bad design: the manifold must be below the pumps' inlets. Think about it. If there is a head of oil above the manifold and the manifold is above the pumps' inlets, then for cross contamination to occur, debris has to travel uphill against a positive head of oil. Highly unlikely.

And, more importantly, if this machine did require suction strainers due to brain-dead dumb design, an informed machine owner would never buy it in the first place.

Anyway, I prefer not to argue with people who've convinced themselves of the merits of suction strainers - or as in the above case, use them as a substitute for proper design. I just refer them to pump manufacturers' recommendations. Just the other day I was flicking through an old Rexroth manual that dates back to 1979. Here's an excerpt of what it says about suction filters/strainers:

"The advantages of suction filtration are strongly outweighed by the disadvantage of the pressure drop created by the elementů Any benefit the suction filter offers by keeping contamination out of the pump, is offset by the possibility of damaging the pump because of cavitationů"

"Another major disadvantage of the suction strainer is that it is located inside the oil reservoir which makes it inconvenient to service. It is for this reason many suction strainers in hydraulic systems go unserviced until they starve the pump and cause cavitation damage."

"Due to these disadvantages, a fine degree of filtration at the inlet of the pump is specifically not recommended (italics theirs not mine)."

It speaks volumes about the hydraulics industry, that this 30-year-old advice from a leading hydraulic pump manufacturer is still widely ignored today.

I wonder if Moneyball will have a more rapid influence on the way Big League baseball teams are managed? Maybe it already has.

"This book has the potential to save many organizations lots of money. It should be on the bookshelf of every engineer, supervisor, planner and technician who deals with hydraulic equipment... it's worth its weight in gold." Find out more

Alexander (Sandy) Dunn
Plant Maintenance Resource Center

3.   How to consolidate your hydraulic oil inventory

Have you got more than one type of hydraulic oil taking up space in your oil store? If so, you're not alone. For some practical advice on how to go about consolidating your hydraulic oil inventory, read my column in the May-June 2009 Issue of Machinery Lubrication available here

To get your complimentary subscription to this informative magazine (US and Canada only) go to: http://www.machinerylubrication.com/hydraulic1.asp

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 editor@hydraulicsupermarket.com 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 20 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: http://www.InsiderSecretsToHydraulics.com

5. Help us spread the word

If you've found our 'Inside Hydraulics' newsletter interesting and informative, then chances are you have a colleague who would too. Help spread the word about 'Inside Hydraulics' by forwarding this issue to a colleague. If they share your interest in hydraulics, then they will surely appreciate being told about this newsletter.

New subscribers can get the newsletter by completing the form at http://www.insidersecretstohydraulics.com

6. Tell us what you think

We would love to hear what you think of this issue of our 'Inside Hydraulics' newsletter. And of course, if you have any suggestions for future issues, please send us those too.

Just e-mail the editor at: newslettersuggestions@hydraulicsupermarket.com

Copyright 2000-2009 by HydraulicSupermarket.com. All rights reserved.

To subscribe to this newsletter, go to: