By Brendan Casey,
HydraulicSupermarket.com

In the August issue of my “Inside Hydraulics” ezine, I ran a little competition in which I invited readers to send me their favorite must-not-do or 'Cardinal Sin' related to hydraulics. Several hundred members submitted entries and I've edited and compiled them all into one, succinct document, with the top ten sins described below. Another 122 are included in the attached PDF.

Judging the winners was no easy task. As the final document shows, there were many good entries. But here are my top 10, in no particular order:

The corporate award goes to Case New Holland (CNH). The guys at CNH must pay attention to their hydraulics because I received multiple entries from their various locations around the world. Truman Lomi who works for CNH, Sydney Australia scores for this one:

1. “Condemning a hydraulic component as faulty without proving it through a logical process of elimination.” If you employ people to work on hydraulic equipment and you do nothing else but drum this one into their head, you will save yourself a small fortune.

2. Truman’s colleague at CNH Burr Ridge, Ill., Bruce Arndt, also makes the top ten with this no-no: “Not ensuring all accumulators are completely discharged prior to commencing work on a system.” This should be obvious but isn’t always to the uninitiated. A mechanical equivalent is when you are trying to disassemble a spring-applied air brake without considering the potential energy of the  compressed spring — which you can’t see — you have to know it’s there and take the necessary precautions.

3. Kudos to Kevin McCaffrey and his team at Excel Hydraulics, Sydney, Australia. They did a brainstorming session around this and came up with many good submissions. But this ‘sin’ stood out for me: “Measuring o-rings for replacement purposes (it’s the grooves you should be measuring).” This may seem harmless enough on the surface, but the upshot of it is it often results in the wrong seals being installed. And this can cause a lot of heartache. 

4. Sylvain Roy who works for Trican Well Service, Red Deer Canada, nailed this common mistake which gets a lot of inexperienced circuit designers into bother: “Believing piloted operated check valves are motion control valves — and that counterbalance valves are load holding valves.”

5. The best ‘Cardinal Sins’ cut to the quick. Like this one sent in by Sebastien Gagnon, from Equipements Anderson, Chesterville Canada: “Allowing a hydraulic hose to twist when it’s being tightened.”

6. Stephen Brosnan, who works for the CSIRO in Brisbane, Australia joins the winners list too with: “Modifying the hydraulic (or electrical) circuit but not updating the schematics to reflect the changes.” There’s nothing worse than trying to troubleshoot a complex hydraulic system with a drawing that’s not accurate. And in the case of an electrical circuit, I remember once working with a battle weary electrician, troubleshooting a problem on an electrohydraulic system, and as soon as he realized the drawing wasn’t accurate he became very wary, stating: “That's how you get fried!”

7. Steve Cater of Freco Fluid Power, Nepean, Canada makes the cut with: “Replacing a component which has failed catastrophically without cleaning the tank and flushing the system.” Anybody who’s worked in the hydraulic repair business knows anyone who commits this ‘sin’ causes a lot of weeping and gnashing of teeth.

8. Another ‘Cardinal Sin’ that really is the hallmark of a rank amateur, is this one submitted by Hendrik de Villiers from Bahrain: “Applying silicone sealant to tank lids or o-rings.”

9. And here's another trap for the uninformed, submitted by Michael Calverley who works for Baker Atlas in Algeria: “Assuming the filter element is correct — just because it fits.” I committed this sin many years ago when young and inexperienced and only through sheer luck did I avoid a very expensive disaster. It’s rather a long story for another time.

10. And finally, George Robertson from Fugro in Aberdeen, Scotland summed up this whole exercise with: “People who have been around hydraulics for years, who “know it all’ making the same mistakes again and again, and not taking the time to really understand how hydraulics work.” When it comes to hydraulics, I don’t think you ever know it all. There’s always something to learn, AND there's always a deeper level of understanding to be had about the things you ‘know.’

To read 122 other “sins” in PDF format, click here. To subscribe to the “Inside Hydraulics” enewsletter, click here. Brendan Casey has more than 20 years experience in the maintenance, repair, and overhaul of mobile and industrial hydraulic equipment. For information on reducing the operating cost and increasing the uptime of your hydraulic equipment, visit his web site www.hydraulicsupermarket.com or contact him at bcasey@hydraulicsupermarket.com.