This is the second post of a two-part tip series that dives into couplings, how they work, and how to optimize their performance through best-in-class lubrication.
Our first post covered the basics – what are couplings, the two most common types of couplings (gear and grid couplings), and common operating challenges. This tip will focus on lubrication best practices.
In couplings that require lubrication, it is critical that the proper lubricant be selected, applied correctly, and reapplied at the proper frequency. It is also important that the coupling be in good working order, in particular have functional o-ring seals and mating gaskets to prevent lubricant leakage.
Oil is, without a doubt, the best coupling lubricant, as it allows free and complete coverage and there is no thickener to separate or dry out (like you would have in a grease). Mobil products that have performed well in couplings include Mobil SHC Gear SHC 22M and 46M. These are high viscosity oils, made from PAO (polyalphaolefin) base stocks that contain extreme pressure additives to protect against sliding wear. They are also not susceptible to the centrifugal separation forces created during coupling rotation.
If you decide to use a grease for coupling lubrication, you should select a grease based on American Gear Manufacturing Association specifications CG-1, CG-2, and CG-3. The differences between the three ratings includes rotational speed, misalignment allowed, surface temperature and re-greasing interval.
Maintenance best practices
If you use a grease, the product’s performance is only as good as the greasing procedures used. First and foremost, if the coupling leaks and flings out the lubricant, the coupling will have a short life. Make sure o-rings and seals are in place and have integrity. Alignment is also key. The coupling must be aligned. If it isn’t, sliding wear will occur and shorten the life of the coupling.
Here are a few other important practices:
Hopefully this two-part tip series was helpful. If you have any further questions or comments, leave us a comment in the section below.
Thank you for the information on the classifications and how these must be used to select the type of grease. Best regards, Rick Russo.
Jose - The differences between the three ratings includes rotational speed, misalignment allowed, surface temperature and re-greasing interval. This link will give you the specific for each rating.
What do the CG-1, CG-2 and CG-3 specifications mean when you are selecting a type of grease?
This information is very useful, with very good feedback and very accurate technical data. Thank you. Rick Russo.