In This Issue:

• Readers Challenge Winner

• Today's Tip: Quit Replacing Those Seals

• Book Bits: Heat Means Trouble for Grease

• Q & A: Lube Selection Caution

Readers Challenge Winner

CONGRATULATIONS to Chris Gillard, Shell Global Solutions - the winner of last week's Readers Challenge.

See the winning response, as well as other responses at: http://www.lube-tips.com/challenge/

Today's Tip

Quit Replacing Those Seals

• If you are constantly changing gearbox oil seals, check the gearbox breather for plugging. When breathers become clogged, internal gearbox pressure can build and find its way out through oil seals creating a false impression that the seal has failed. This can become more problematic during summer months. (Submitted by Mukesh Sharma, Sharjah Cement. Thanks Mukesh!)

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Book Bits

Heat Means Trouble for Grease

From "The Lubricating Grease Guide"

Greases fail more rapidly as temperature of operation increases. The most obvious reason for failure lies in the melting point of the thickener or dropping point of the grease. The latter involves a complex of melting and bleed. Evaporation may be significant at high temperatures. Oxidation also increases rapidly as temperature rises. There are useful guidelines for heat resistance of greases in service which take all these factors into consideration.

More information about the book "The Lubricating Grease Guide"

Q & A

Lube Selection Caution

"We would like to standardize on one brand of oil for all our gearboxes, but our worm gear manufacturer tells us we shouldn't use the extreme pressure (EP) gear oil we use for our reduction gears for this application. Why can't you use EP oil for worm gears?"

Many EP gear oils contain sulfurous additives. These additives are designed to chemically bond to the metal surface of the gears and other components under boundary lubrication conditions to prevent welding of asperities on the two opposing surfaces. While vital in preventing metal-to-metal contact in boundary lubrication regimes, they can be corrosive under certain conditions, particularly to yellow metals such as copper, brass and bronze that are commonly used in industrial worm gears and other components.

The best approach to selecting the correct product for a given application is to gain a thorough understanding of the gear type, metallurgy and operating conditions of the component and to discuss these points with your lubricant supplier and equipment manufacturer. The correct lubricant can then be selected based on load, speed, operating temperature and additive requirements.

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