Hey Prairie Dawg, “What bearings do you recommend?”

Prairie Dawg Practical by Tim Holmberg, DEMI Equipment

In today’s vast marketplace with so many options comes the not so easy question of what replacement bearings should I be purchasing for this repair project? Do I let pricing regulate my decision or do I stay the course and continue as my grandad would have and go with the “Made in the USA” labeled carton? Or is that familiar labeled package and its contents really just an imported inexpensive bearing in a now overpriced misleading box?

• The best way to work through these game changing choices is to do your research — especially if the bearing or bearings are going to be in the five-figure repair price range. No matter if domestic or import there should be some representative who can come visit and understand the application as well as fitment requirements when needed. This person should be able to tell you the bench load characteristics of the bearing associated with the RPM ratings to maintain proper fitment tolerances provided by the manufacturer. If these often static measurements are messed up ever so slightly it becomes “lights out” due to extreme heat and pressure build up resulting in locked up or frozen boat anchors.

• If these replacements involve a bearing smaller than a two-inch diameter shaft mounted application, you can probably get away with just about anything priced competitively and live to tell the tale of how long it lasted (or quickly it failed) without much heartburn. I have found that the worse possible thing you can do to prematurely destroy most any bearing is to over lubricate it, surprisingly enough — including an oil bath application/environment to start with. Bearings are extremely finicky precision machined objects that if subjected to an over-lubricated environment can actually start to overheat due to the bearing’s moving components being forced into a sliding motion rather than its designed rolling atmosphere, hence the term “roller bearing”. Common sense physics tells us that anything in a sliding motion or friction non-rolling motion will immediately create excessive heat. And much more heat from an over-lubricated bearing as it causes an immediate galling action and then a complete metal-bonding destruction. At this point most opportunities to easily replace the bearing have become most difficult and often require extreme heat and cutting to remove the hardened portions that have fused to the shaft.

• Some bearings are actually designed for a perfect tolerance fit. This is considered a friction-fit bearing — like those found inside a combustion engine or an extreme duty rock crusher — where they will see crazy amounts of varying forces and conditions, but because of their ever-evolving design, they are now capable of lasting 20 plus years if properly lubricated and maintained. These are typically bronze or precious metal finished that is proven to absorb and release quality clean fossil fuel or synthetic oil.

Almost everything manufactured today would not exist if not for some sort of specialty bearing. The bearing industry has been around since before my grandpa and will definitely be here long after my time on Earth has passed. My suspicion is that bearings (no matter how well designed) will fail and need changing for some reason or another. The reason may be as simple as too much grease or oil due to lack of training or understanding. Either way, read the directions that accompany the bearing and give yourself the best possible chance to keep your bearings running a long distance.

Oh, and one last thing: don’t ever over RPM your bearing limits unless you want to see, and quite possibly feel, a grenade exploding. Be careful out there and keep a bearing or two in your inventory for a rainy day.
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Questions or Comments? Tim Holmberg prairiedawg@pdpractical.com.
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Tim Holmberg
2915 Idea Ave.
Aberdeen, SD 57401