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Maintenance Hydraulic Troubleshooting on Interactive CD

Our nationally acclaimed Maintenance Hydraulic Troubleshooting workshop on six fully interactive CD's.  Includes our MHT workshop manual.  6-CD Set - $1200 Individual CD's - $250 + Shipping and Handling.            Click on http://gpmhydraulic.com/mhtcds.htm to find out more. 

This time of year, many plants are temporarily shut down - either because of market conditions or for scheduled maintenance shutdowns.  Whatever the reason, a shutdown is the perfect opportunity to improve the reliability of your hydraulic systems.  Maintenance departments frequently take advantage of this time to make repairs or perform tests that cannot be done while the machines are operating.  But often the only attention a hydraulic system gets is an oil and filter change.  There are several checks and procedures that can be done during down periods that will improve the efficiency and operation of the system when production demands are high. The following are preventive maintenance checks that will improve the performance of the systems and machines:

Reservoir

Figure 1

Now is an ideal time to clean the reservoir.  Maintenance mechanics and electricians chuckle when I tell them that the reservoir should be cleaned at least once a year.  While consulting with one large wood products plant, the mechanic said that the reservoir on one system hadn’t been cleaned since the mill started up 17 years ago!  Other than oil storage, the two main purposes of the reservoir are to allow contaminants to settle and to dissipate heat.  If the reservoir is not cleaned, not only will its ability to dissipate heat be diminished, it will act as a heat sink.  Temperatures can easily soar well above the maximum recommended temperature of 140 degrees Fahrenheit.   Oil will then start breaking down causing sludge and varnish in the system.  If the contaminants are not removed from the reservoir they will be drawn into the pump causing premature failure of the system components.  Be sure to use a lint free cloth when cleaning out the reservoir.  If a solvent is used, be sure it is one that is recommended for hydraulic systems.  Even very small amounts of the wrong solvent can impair certain additives.

System Cleaning and Flushing

When the oil is removed from the reservoir it should be filtered to 1 micron into a storage tank with a flushing and filtering unit that will remove solid contaminants and water.  Unless the oil is severely degraded it is not necessary - or even desirable - to change it.  Run the oil through the 1 micron filters when re-filling the unit.  The entire system should then be flushed to clean the oil in the lines to the valves and actuators.  Shown above is the flushing unit that is used by our consultants during this process.  System flushing is done by connecting the inlet and outlet lines of the cylinders and motors together.  If possible, electrically or manually actuate the directional valves to allow the fluid to re-circulate through the piping.  If this is not possible, then bypass the directional valves by connecting the pressure and tank lines to the outlet lines to the actuators.  Use the existing pump on the machine to re-circulate the oil through the lines.  Connect the flushing unit so that it re-circulates the oil in the reservoir through the 1 micron filters.  Allow the system to run for as long as possible.  Below, the purity of the oil is shown for a system before it was flushed then after 1, 4 and 16 hours.

Reservoir Heater Setting

Check the heater thermostat (no. 2 in Figure 1 at the top of the article) on the reservoir to verify that it will turn on at a minimum of 70 degrees Fahrenheit.  If the pump is mounted on top of the reservoir and the oil temperature drops below approximately 40 degrees Fahrenheit then cavitation will occur. 

Oil Level Switches

 
Most reservoirs utilize two switch settings (no. 7 in Figure 1), a warning and a shutdown. The problem with this is that the difference between the two levels may be several hundred gallons of oil.  By eliminating the warning switch and setting the shutdown at a higher level, oil loss will be minimal when a hose ruptures.

Breather Cap

 
Verify that the breather cap (no. 8 in Figure 1) has a rating of approximately 10 microns.  This is the first line of defense for contaminants entering the tank.  Depending on the location, the breather cap may need to be changed a couple of times a year.  Other options include pressurizing the reservoir with an internal bladder or using a moisture removal type breather.  Remember that money spent upgrading your breather cap is NEVER money wasted!

High Temperature Switch 

Mineral oil will start breaking down at 140 degrees Fahrenheit and many systems will not shut the unit down until the oil temperature reaches 160 degrees.  Hydraulic systems are designed to operate below 140 degrees Fahrenheit.  If the oil temperature rises above that level then a problem in the system exists.  This could be caused by a cooler malfunction, excessive bypassing at the pump, valves, cylinders and hydraulic motors.  Set the high temperature switch (no. 10 in Figure 1) at 140 degrees Fahrenheit to shut the pump off, preventing oil breakdown.

Heat Exchanger Flushing and Cleaning 

The tubes in a water type cooler (no. 12 in Figure 1) should be flushed periodically to remove deposits. A mild alkaline solution such as Oakite or a 1.5% solution of sodium hydroxide or nitric acid can be used.  A cathode type protector can be installed to avoid electrolytic damage to the cooler tubes.  If an air cooler is used, verify that the cooler fan is turned on at approximately 120 degrees Fahrenheit and turned off at about 105 degrees.  Keep the fins clean so that daylight can be seen through them.  Combs should be used to straighten the fins on the unit if necessary.

Pump Testing

On variable volume pumps, check the flow out of the case drain line by porting the line into a container and timing it.  This test should be made with the outlet pressure at maximum.  It is not recommended that the line be held during this test.  Secure the line to the container prior to starting the pump.  The normal case flow is 1-5% of the maximum pump volume.  Vane pumps usually bypass more than piston type pumps.  If 10% of the maximum volume flows out of the case drain line then the pump should be changed.

Fixed displacement pumps can be tested by checking the flow through the relief valve. Turn the pump on and record the flow out of the relief valve tank line for 1 minute as shown above.  Then reduce the setting of the relief valve to its minimum setting. There should be less than 10% difference in flow rates between the two tests. If a pump is badly worn then the flow will be considerably less at the highest pressure.

Accumulator Testing

If piston accumulators are used then the charging rig should be installed and the oil bled off the top of the piston. With the pump on and the bleed valve open, there should be little or no flow exhausting out of the bleed valve. If a continuous flow exists, then the piston seals or barrel are badly worn. If no flow exists then re-charge the accumulator to the proper dry nitrogen level.
Bladder type accumulators should also be tested by installing the charging rig on the valve stem. Due to osmosis, the dry nitrogen can seep through the bladder over a long period of time. If necessary, pre-charge to the recommended pressure.

Hoses

Check the hoses in the system for the proper length and wear.  Hoses infrequently burst because the rated working pressure is exceeded.  They normally rupture because of a poor crimp or the hose is rubbing on a beam, another hose, etc.  Hose sleeves are available on a reel from a variety of manufacturers if rubbing cannot be avoided.  Hoses should usually not exceed approximately 4 feet in length unless they move with a machine.  Also inspect the system piping to verify that prior to connecting to a valve bank or cylinder a hose is installed.  The hose will absorb the hydraulic shock that is generated when the oil is rapidly deadheaded.  An exception to this rule is that hard piping should always be used when connecting to a vertical or suspended type load.  Pilot operated check valves and counterbalance valves are used to hold the load in the raised position. 

Clamps

Inspect the system clamps to verify that that the proper hydraulic clamps are used to clamp hydraulic lines. Beam and conduit clamps are not acceptable, as they will not absorb the shock generated in the piping or tubing. The clamps should be spaced approximately 5 feet apart. A clamp should also be installed within 6” of the pipe or tubing termination point.

Once the system is thoroughly inspected and upgraded a preventive maintenance schedule should developed to perform these checks on a regular basis. Many times no thought is given to the hydraulic system as long as it is running and the machine is operating. By performing the checks in this article, your systems will operate at maximum efficiency, operate safer and reduce downtime.

2007, our busiest year ever finally wound down in December allowing us to catch up on some much needed company infrastructure upgrades.  As a result, we will now be able to provide troubleshooting manuals in full color, more rapidly produce troubleshooting ebooks, provide offsite consulting services and in general respond faster and more completely to the needs of our customers.  By the way, if you already have a black and white manual and you would like one published in color, please call or email me - (770) 267-3787, gpm@gpmhydraulic.com   Of course, all of these changes are not without their associated learning curves - new hardware, new software, the trials of Windows Vista on our new computers and even a change in our accounting program.  But we're confident that the time and money spent will be more than offset by the benefits.

Al started November off by teaching the first three weekends at Magna's automotive plant in Greenville, South Carolina. In between those courses he presented a seminar at IDCON's Maintenance Conference in Raleigh, North Carolina.  There he saw several old customers and friends as well as met some new ones. One of the conference attendees was John Dudenhoeffer, maintenance manager at Grain Processing Corporation in Washington, Indiana.  John found the workshop so beneficial that he scheduled GPM to teach three, 1 day workshops for his plant in January.

Al also taught our 1 day, Troubleshooting Bosch Proportional Valves workshop the following week for an MDF plant in central Georgia.  As a result of the training, the company purchased one of GPM's flushing machines to help extend the life of their valves.

Be on the lookout for Al's article on "Can you handle the Pressure" in the current issue of Paper 360 magazine. If you're in Canada, you'll find his upcoming article in Canadian Wood Products magazine on things to do when your mill is down for a few days.

As for Alan, he has been busy playing catch up on his drafting. We have several in-plant programs scheduled for the 1st & 2nd quarter of 2008.  Temple Inland, Unilin, Grant Forest Products and Caraustar, all eagerly awaiting their advanced programs.  Between bouts of drafting, Alan managed to teach a MBHT workshop for Goodyear Tire in Gadsden, AL.  The year end also brought Alan a new son-n-law.  Congratulations to Alan's daughter Brittney who married Allen Lotz on December 31st.

Jack has taught workshops in Corpus Christi, TX and Florence, SC.  He has also been called for consulting trips to Hazard, KY, Macon, GA and Savannah, GA.  Between all of these, he has been upgrading our computer hardware and software and developing advanced troubleshooting programs.

I've been trying to learn all of the new equipment and software in addition to my usual duties.  They tell me that all of these upgrades will make all of our jobs easier.  We'll see....

3. In-plant consulting and 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 on how GPM can help you? Go to http://gpmhydraulic.com/troubleshooting.htm

Troubleshooting Proportional Valves

The complete guide to troubleshooting and maintaining linear positioner circuits with electronically controlled proportional valves.  The same manual used in our acclaimed Troubleshooting Proportional Valves public seminar.

                    $49.95 + Shipping & Handling

To order this and other exciting products online, visit the GPM Store!

4. New for 2008!  Off-site Consulting

It isn't always necessary for a consultant to travel to your facility to assist with hydraulic issues.  Often we can help troubleshoot hydraulic problems over the telephone, fax and email.  Or perhaps you would like us to make recommendations for preventive maintenance scheduling or equipment upgrades.  When this is the case, there is no need to pay for travel expenses and we are able to offer a reduced consulting rate.  Off-site consulting is offered at the rate of $75 per hour with a one-hour minimum.  Call us at (770) 267-3787 or email at gpm@gpmhydraulic.com for more information.

5. 2008 Public Workshops

Troubleshooting Proportional Valves 2008

Click Here for a Full Description of the Workshop

8 Hour Course

Registration Fee $450.00 Per Person. 

Save $100 if attended in conjunction with our three-day Maintenance Hydraulic Troubleshooting workshop

Only $350.00 If Attending Our 3-Day Maintenance Hydraulic Troubleshooting Workshop The Same Week. (See 2008 MHT Schedule Below)

            Learn How To Troubleshoot and Maintain Linear Positioner Circuits with Electronically Controlled Proportional Valves

Maintenance Hydraulic Troubleshooting 2008

3 Day Course

Registration Fee $850.00 Per Person

Learn More About Our Maintenance Hydraulic Troubleshooting Course 

2008 Maintenance Hydraulic Troubleshooting Schedule The proportional valve icon beside a date indicates that our exclusive one-day Troubleshooting Proportional Valve Systems workshop will be conducted at the same location and may be included with your Maintenance Hydraulic Troubleshooting workshop for just $350!
Date	City	Location
January 22 - 24	Cordele, GA	To Be Announced
January 29 - 31	Shreveport, LA	To Be Announced
February 5 - 8	Circleville, OH	To Be Announced
February 13 - 15	Russellville, AR	To Be Announced
February 18 - 20	Blytheville, AR	To Be Announced
February 26 - 28	LaGrange, GA	To Be Announced
March 4 - 6	Fresno, CA	To Be Announced
March 11 - 13	Statesville, NC	To Be Announced
March 18 - 20	Laurel, MS	To Be Announced
April 8 - 10	Madison, GA	To Be Announced
April 15 - 17	Newberry, SC	To Be Announced
April 22 - 24	Decatur, AL	To Be Announced
May 6 - 8	Saraland, AL	To Be Announced
May 13 - 15	Eugene, OR	To Be Announced
May 20 - 22	Savannah, GA	To Be Announced
June 3 - 5	Rocky Mount, NC	To Be Announced
June 10 - 12	Cleveland, TN	To Be Announced
June 17 - 19	Tupelo, MS	To Be Announced
July 22 - 24	Ruston, LA	To Be Announced
July 29 - 31	Florence, SC	To Be Announced
August 12 - 15	Spartanburg, SC	To Be Announced
August 20 - 22	Bradford, PA	To Be Announced
August 25 - 27	Roanoke, VA	To Be Announced
September 16 - 18	Greenville, SC	To Be Announced
September 23 - 25	Conyers, GA	To Be Announced
September 30 - October 2	Summerville, SC	To Be Announced
October 7 - 9	Tuscaloosa, AL	To Be Announced
October 14 - 16	Smithfield, NC	To Be Announced
October 14 - 16	Tallahassee, FL	To Be Announced

*For Only $350.00 More Attend Our Troubleshooting Proportional Valves Workshop The Same Week.

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Hydraulic Schematic Symbols Explained

This interactive CD is the fastest, easiest way available to learn hydraulic schematic symbols.$49.95 + Shipping & Handling. Find out more, go to http://gpmhydraulic.com/symbolcd.htm

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GPM Hydraulic Consulting, Inc.

Box 1376

Monroe, GA 30655

(770) 267-3787

gpm@gpmhydraulic.com