The Book of Knowledge

Gears are wonderful things. Unfortunately, they require support from shafts, bearings, and some sort of housing to be useful. Without these things, they are just interesting pieces of artwork. So, after the high of developing the perfect combinations of ratios, center distances, face widths, and helix angles, you have to figure out how to package your creations up and send them off to work.

Hard as it might be to believe, there are engineers and scientists that feel as passionately about bearings as we do about gears. They do not have quite the history we do, but they make up for it by publishing thousands of articles and doing tons of research. Every gearbox designer has a shelf full of bearing catalogs to reference; the best designers even know what page to flip to for the information they need to properly select the bearings available.

Back when I started designing gearboxes in the 1970s, we had a preferred bearing supplier who sent experienced engineers to our aid the minute we called. Besides being experts, they were wonderful teachers. [Unfortunately, bearing companies can no longer afford such big staffs.] If you asked the right questions, you learned lots about both the written and the un-written rules of using taper roller bearings. Very rarely did we “need” to use other bearing types; especially after a disastrous foray into the “dark side” of “shim-less” ball bearings in an effort to reduce assembly labor.

I was part of a team that was assigned to clean-up that mess. Yes, adjusting end play on single row taper roller bearings is time consuming. It also complicates the mountings. And the life calculations taxed our limited computer capabilities. But the ball bearings did not like the operating conditions many of our customers subjected them too; uneven loads, shock, vibration, and other irregularities made the balls act like little ball peen hammers on the races and we went back to the “old family recipe” of all single row taper rollers, all the time. Unless the loads got high enough to require double row taper rollers, which got even more complicated. Or a bevel gear needed “locating.”

There was so much to learn that the pages started to fall out of my favorite catalog. Eventually, I made photocopies of the frequently used ones and added them to my ever growing “book of knowledge.” Long time readers understand that I am a bit of a crank on the importance of good notes and procedures so you get consistent results. When the pressure is on, deadlines loom, and you are tired, a good set of notes will save you.

I can see your eyes rolling back in your heads, you internet dependent whippersnappers! Why keep notes when you have the Google? Gear Technology’s archive is always there. Surely the bearing info is floating around the ether as well. Aside from power outages, weak cell signals, and favorite pages disappearing, you are absolutely right. Me, I rest easier knowing that the chart on “acceptable” bearing arrangements I copied from that AGMA standard is in my binder along with the highlighted chart on the fits I need to use.

About Charles D. Schultz 672 Articles
Charles D. Schultz is President of Beyta Gear Service and one of Gear Technology's technical editors.