P.O. Box 1376
Monroe, GA 30656
(770) 267-3787 gpm@gpmhydraulic.com 		November 2012

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'Troubleshooting Hydraulics' Newsletter 

www.gpmhydraulic.com 


Al Smiley
President
Jack Weeks
Hydraulic Consultant
Alan Dellinger
Hydraulic Consultant
Robin Haywood
Training Coordinator

In This Issue

1.  GPM Has Grown!

2.  Call GPM for Emergency Hydraulic Troubleshooting

3.  Is It Time For A Hydraulic Reliability Assessment At Your Plant?

4.  My Machine is Moving More Slowly Than it Should

5. Spread the Word!  Tell Others About the GPM Newsletter

6.  GPM's Hydraulic Cylinder Repair CD
1.  GPM Has Grown!
  By Al Smiley
You may have noticed that there hasn't been a Hydraulic Troubleshooting newsletter in quite a while.  We haven't forgotten, we just haven't had time!  That should be changing soon.  With the recent surge of classes, consulting and hydraulic reliability audits, we have hired two new trainees and I would like to take the opportunity to introduce you to them.

Hank Ayers
Hank has 18 years experience in servo and proportional valve repair.  Hank's expertise was an invaluable resource years ago when we developed our one-day Troubleshooting Proportional Valves workshop.  We expect his extensive hydraulic experience to be a considerable asset to the furtherance to GPM's mission.
Chris Dellinger
Son of GPM's Alan Dellinger, Chris has grown up around hydraulic consulting and promises to be a welcome addition to the GPM team.  Chris has been doing an excellent job drafting on a contract basis for quite some time.  His enthusiasm and strong work ethic should enable Chris to advance to a full fledged instructor and consultant very soon.		 We expect these two fine gentlemen to enable us to expand with no compromise of the superior product you have come to expect from GPM Hydraulic Consulting!
C.A. (Al) Smiley, Jr.  founded "GPM" in october of 1994. Al initially worked with a leading hydraulic distributor from 1977 to 1986.  In 1987, his father Carl A. Smiley, Sr. hired Al to work with his company, Southeast Maintenance Consulting services.  Since then he has taught and designed hydraulic troubleshooting programs for companies throughout the United States and Canada. Al does the technical writing for GPM's "Troubleshooting Manuals"  He is certified and registered with the Fluid Power Society as a Fluid Power Specialist. He earned a Bachelor’s Degree in Education from the University of Mississippi in 1977.  He writes columns for Hydraulics and Pneumatics, Southern Lumberman, Canadian Wood Products and Papermill 360 magazines on hydraulic troubleshooting methods. Al is married with two boys and a granddaughter.  He is a musician and an avid golfer.
Where's Jack? Bacon Grease Dressing Alan’s Back Roads
I've been on the move quite a bit during the last several months.  Since the last newsletter I have made 28 separate trips to such exotic locales as Guntown, MS, Fordyce, AR, Hosford, FL and Prosperity, SC just to name a few.  I also spoke at the ExxonMobil symposium in Philadelphia, PA and had to endure the hardship of trips to Corpus Christi, TX and Fernandina Beach, FL (it's a tough job, but someone has to do it...).  I even made one trek across the country to Clatskanie, OR where we stayed in nearby Astoria, the town where the 1985 movie "The Goonies" was filmed.  In May we bought a house in Conyers, GA.  Since then, we have spent 12 nights there. 1/2 cup bacon grease
1 to 2 tablespoons vinegar
Pinch or two of granulated sugar
Fresh garden lettuce, rinsed
1/3 cup chopped green onions
Crumbled bacon (optional)

Heat bacon grease in saucepan on medium heat. When grease begins to simmer, stir in vinegar and sugar to taste. Toss the lettuce and chopped green onions together. Remove grease mixture from heat and serve immediately to the side of the salad. Garnish with crumbled bacon bits, if desired. 		In January I had the pleasure of traveling to Lynchburg, Va. Located in the foothills of the Blue Ridge Mountains. Lynchburg was the only major city in Virginia that did not fall to the Union in the American Civil War. Being the history enthusiast that I am, I did not have any time to take in any historic sites. My visit to Virginia was a business trip. I taught a 4 day Troubleshooting OSB Hydraulics workshop for a large wood products manufacturer in the area. This was just one of many backroads my GPM travels carried me to in January, and definitely the one I enjoyed the most.
2.  Call GPM for Emergency Hydraulic Troubleshooting

Nothing is more expensive than unscheduled down time.  GPM’s customers know they can call whenever they have a troubleshooting issue they simply can’t resolve.  With over 50 years experience dealing with hydraulic failures, our consultants have the resources to help troubleshoot whatever hydraulic problem you encounter.  Whether you’re experiencing a total system outage, repeated component failure or just need a professionally designed preventive maintenance schedule, the consultants at GPM can help.  Call GPM for 

            In-plant  Troubleshooting

            Leakage Problems

            Pressure Settings

            Shock Problems

            Preventive Maintenance Scheduling

            Hydraulic Troubleshooting Manual Development

            Startup Consulting and Recommendations

            Heat Problems

            Repeated Component Failures  

            Speed Problems

Do you want to learn more about how GPM can help you? Go to http://gpmhydraulic.com/troubleshooting.htm

 

3.  Is It Time For A Hydraulic Reliability Assessment At Your Plant?
The only preventive maintenance and reliability functions that most plants perform is to change the filters regularly and to check the oil level. When the machine fails, there is little or no information about the system to refer to when troubleshooting.  Our consultant will first perform a customized Reliability Assessment on each of your in plant machines. You will receive a Reliability Report on each system with recommendations for immediately improving the system operation, shock, heat, leakage, speeds, etc. You will also be provided with a Reliability and Preventive Maintenance Schedule that can be used to check the condition of the system on a regular basis, reducing un-scheduled downtime. The recorded information will also provide a valuable reference for troubleshooting if a failure of the machine should occur. Pictures will be included throughout the report to identify the reliability test points in the system.  The Assessment will be conducted while the machine is operating and will include the following: 
  • Testing of the pump(s) to determine if the proper volume is being delivered to the system. By making this test regularly the pump can be replaced on a down day and not when it fails and interrupts production.
  • Checking the accumulators to make sure they are properly pre-charged which is necessary to achieve the desired speed to maintain production.
  • On any given hydraulic system, there should be some lines that are hot (above 130 degrees), warm (100-130 degrees), and cool or at ambient temperature. By checking the temperature of these lines on a regular basis a component failure can be found before the system fails completely.
  • One of the main issues in a hydraulic system is leakage. One drop of oil that drips once per second will lose 405 gallons a year. If leakage is occurring there is a reason for it. Our consultant will identify the cause of the leak and recommend the necessary fix to prevent it from occurring in the future.
  • One of the biggest problems in systems today is that the pressures are out of adjustment which causes excessive force, heat, leakage and wasted electrical energy. Our consultant will identify any pressure setting issues and many times correct them during the assessment.
  • Check to verify that the pipe and tubing clamps are properly spaced and are of the proper type. 
    Make sure that the hoses are properly installed to prevent pre-mature failure and oil loss.
  • Check the condition of the filters if a visual or electrical indicator is available.
  • Verify that the air and water heat exchangers are operating properly to reduce the oil temperature to an acceptable level. If the oil temperature is above 140 degrees then oil will start breaking down causing sludge and varnish in the system. 
  • Check the condition of the breather cap and recommend a maintenance schedule.
  • Sound checks to determine pump cavitation, aeration or valves bypassing in the system.


Schedule a Reliability Assessment at your plant today for a full report on the condition and recommended improvements for your systems. Then by using the customized Reliability and P.M. Schedule downtime, parts cost and oil loss will be reduced.

4.  My Machine is Moving More Slowly Than it Should
  By Jack Weeks
Most industrial machines slow down over time.  The most common response we see to this problem is to turn up the pressure.  Sometimes this works.  The machine speeds up (or at least gets louder and appears to be moving faster) and the general consensus is that slow movement means more pressure is needed.  But pressure and speed really don't have anything to do with each other.  The speed of an actuator is determined by two factors:
  • The rate of oil flow
  • The size of the actuator
Think of a hydraulic actuator as a bucket.  The higher the flow rate, the faster it will fill.  Also, the smaller the bucket, the faster it will fill.  Pressure is irrelevant to speed.  Pressure is determined by resistance to flow.  In other words, the harder an actuator is to move, the more pressure will be developed in order for flow to pass.  But the actuator is not the only resistance in most machines.  Anything that inhibits flow will add resistance.  And most machines have fixed orifices, adjustable flow controls or proportional valves that restrict flow by design.  Many machines have all three.  These components are intended to control speed, so the most efficient way to speed up the actuators is to adjust the flow controls or increase the signal to the proportional valve.  So why does turning up the pressure increase the speed?  This is because there are three factors that affect the flow through an orifice:
  • Size of the orifice
  • Pressure drop across the orifice
  • Oil temperature
An increase in any one of the three will result in an increase in flow.  And the increase in flow will result in an increase in speed.  Turning up the system pressure will increase the pressure drop across the flow controls and thus increase the flow, but at what cost?  Increasing the pressure will unnecessarily increase the energy consumption of the machine.  Increases in pressure drop also increase temperature because pressure drops that do not result in useful mechanical work generate heat.  And increasing the pressure also results in excessive force.  Absorbed by the machine, the excessive force results in leaks and undue component wear.  The more efficient answer would be not to restrict the flow as much.  But why did the machine slow down in the first place?  It could be that someone adjusted a flow control and slowed things down, but not likely.  It is much more likely that the reduced speed is the natural result of wear.
We must first determine if the pump is actually delivering less flow or if the the flow that is delivered is not being used efficiently by the machine.  As a pump wears, internal bypassing increases and the output at the pressure line decreases.  In variable displacement pumps with case drains, the case flow can be measured to determine the condition of the pump.  For most pumps, case flow of more than ten percent of the total output indicates severe wear.
 
There are exceptions to this, so check the pump documentation for acceptable levels of case flow.  This information and much more can be downloaded from the manufacturer's website.  Fixed displacement pumps usually have no case drain.  Higher than normal case temperature and lower than normal current draw of the drive motor are both good indicators of fixed displacement pump wear but this presupposes that you have some idea what "normal" is.  To test a pump, its flow under load should be compared with its flow at no load.  There should be no significant difference.  If the flow drastically decreases under load, the pump is worn and should be replaced.

If the pump is confirmed to be good, then the machine is not using the flow efficiently.  Valves and actuators must be tested for bypassing.  Methods will vary by application, but if more than a small trickle of bypassing is noted, the component will need to be repaired or replaced.  Flow meters and gauge ports in strategic locations can be invaluable when making these types of checks.
Of course, regular maintenance checks can spot potential problems before they become outages.  A few minutes invested each month measuring temperatures, pressures, current draw and case flow is the key to hydraulic reliability.
Jack Weeks  entered GPM’s organization in January of 1997 as a CAD draftsman and hydraulic instructor. He has trained thousands of electricians and mechanics in Hydraulic Troubleshooting methods. His computerized animations have made GPM's presentations and training CD's the recognized leader in the industry. He received his education from the Georgia Institute of Technology School of Electrical Engineering and the Department of State Foreign Service Institute.  Jack is an experienced draftsman and taught telecommunications equipment operation and repair for the Central Intelligence Agency at American embassies overseas.

5.  Spread the news

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6.  GPM's Hydraulic Cylinder Repair CD

Basic Hydraulic Cylinder Repair Manual on CD!

A step-by-step guide for changing cylinder seals and carrying out minor repair. The manual contains disassembly, inspection of parts, minor repair, assembly, examples of seal failures and their causes, hydraulic cylinder speeds, metric/inch conversion table, fluid power formulas, rod and piston groove diameters. 

$24.99 + Shipping & Handling

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GPM Hydraulic Consulting, Inc.
Box 1376
Monroe, GA 30655
(770) 267-3787

gpm@gpmhydraulic.com