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Lubrication Tips for Reliability Professionals

July 10, 2001 Subscribers: 7,568

Q & A

"Can synthetic lubricants help reduce heat in gear drives? I've heard that they will but I'm not sure if it justifies the higher price."

There are many performance and economic reasons to change to a higher priced lubricant for gear drives. Heat is the critical factor from a mechanical perspective.

As the heat goes up in the gearbox the viscosity thins. As the viscosity thins there is an increase of boundary conditions (metal to metal contact) which generate more heat. The frictional heat serves to further thin the lubricant, causing a circular decay in the effectiveness of the lubricant.

Synthetics have higher viscosity indices (VI's) generally. This serves to resist the problems associated with hot drives. Synthetics have been used to effectively reduce the operating temperature of gear drives by 10 to 50 degrees F.

Today's Tip

• When converting a gearbox from petroleum to synthetic - regardless of the synthetic base - it is advisable to thoroughly clean and then flush the gearbox with a charge of the new base material before putting the unit back in service. For some synthetics this is simply necessary, such as with water soluble PAG oils. For other, such as PAOs, it is just good practice and good business.

• Looking for a water-in-oil detection instrument? You'll find eight companies displaying water detection instruments at the Practicing Oil Analysis 2001 Conference. Go to: http://www.noria.com/conference/exhibitors_sponsors.asp
  

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Book Bits

Monthly Consumption Reports. In an operating unit, the basic tool for reducing oil losses is a Consumption Report that is issued monthly to all departments. In fact, where oil losses are excessive, some facilities find it advisable to record weekly consumption. Large lubricant consumers are usually budgeted on the basis of past performance, and the monthly consumption and cost report is checked against the budget as well as the actual gallon of oil and pound of grease used during the period. Such reports effectively keep operating personnel conscious of the problem of leakage. Both trends and 'blips' call for action.

For more information about the "The Lubrication Engineers Manual" go to:

http://www.noria.com/secure/product_detail.asp?catalogid=3

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Lube-Tips is published by Noria Corporation. Oil Analysis and Lubrication Experts