In This Issue:

• Readers Challenge: Diagnosing a Hot Motor Bearing

• Book Bits: Evaluating a Hydraulic Repair Shop

• Today's Tip: Sump Size is Important

• Q & A: Contamination Targets Out of Reach

Readers Challenge

Diagnosing a Hot Motor Bearing

Shortly after regreasing a rolling element bearing in a horizontally mounted indoor motor under light load, the bearing is found to be running hot.

It is an 1800 rpm application in continuous service, greased every three months (nominally). What steps do you take to diagnose the overheating problem?

Submit your answer at http://www.noria.com/challenge.asp before Tuesday, May 27, 2003. Lube-Tips editors will choose the best answer and the $100 recipient will be announced next week.

Book Bits

Evaluating a Hydraulic Repair Shop

From "Insider Secrets to Hydraulics"

Regardless of whether you decide to use the machine dealer, the hydraulic component manufacturer or an independent for your hydraulic repairs, you should always inspect the facilities first.

Beyond the basics such as a clean, dry environment, you should satisfy yourself that the repairer has the necessary facilities to carry out the majority of the work in-house and test the component once it has been rebuilt.

If the repair shop has to rely on outside suppliers to carry out a large portion of the rebuild process, you are likely to end up paying too much for the repair. This is due to the margins of these suppliers being built into the price you pay for the rebuild. For example, if you send a cylinder to a repair shop that has to use outside suppliers for any welding, machining, rod straightening or chroming, their repair price is likely to be more expensive than a repair shop that has the capability to carry out these processes in-house.

More information about the "Insider Secrets to Hydraulics"

Today's Tip

Sump Size is Important

• When evaluating increases in wear metals with spectro analysis, sump size needs to be considered. For instance, a 10 ppm iron increase in a 70-gallon hydraulic system can signal significant pump or motor wear while a 100 ppm iron increase in a 1-gallon final drive may be perfectly acceptable. (Submitted by Alan Johnson, SOS services coordinator, The Halton Co. Thanks Alan!)

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Q & A

Contamination Targets Out of Reach

"We are experiencing problems in reaching our contamination targets on gearbox lubrication oil systems. Finer filters have been recommended on the filter carts. Is this a good idea?"

Before upgrading filtration, be sure to eliminate factors that could cause poor particle count results. Ask yourself the following questions:

• Are your samples are being drawn correctly?

• Are the bottles supplied sufficiently clean for your targets?

• If you are using a particle counter onsite, is it calibrated?

• Are there solid suspensions such as EP additives (Moly, Graphite, Boron etc) in your lubricant?

You then need to identify the cause of elevated particle counts:

• Do you have contamination control procedures for storage and dispensing?

• Is the filter cart being used for the correct amount of time and frequency?

• Is there a need for better-quality breathers and seals?

• Is there a chance of chemical or moisture contamination that may be forming emulsions in the oil?

• Is the alignment and balance correct?

• Are you using the right grade of lubricant?

If all of the above are in order, and your targets are set correctly according to your reliabilty, safety and environmental concerns, then perhaps a small permanent-mount off-line system may address the problem.

But ensure all the above checks have been made before spending money on upgrading the system filters.

Martin Williamson, Senior Technical Consultant, Noria UK Ltd.

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