Very rarely does a gearbox designer have the opportunity to see his or her products at work many years later. Recently I was asked to inspect some gears in a steel processing facility and was delighted to find speed reducers I designed more than twenty years ago.
I wish I could report that they were in pristine condition, but the truth is almost all the gears were severely damaged. Much like the average car or truck, maintenance had been inconsistent and the drives are in need of rebuilding or replacement.
The purpose of the visit was to check the condition of the equipment and to advise on how much longer they could remain in service. Unfortunately there were no written records of when the drives were actually put into service, when they were last repaired, or even when the oil had last been changed. Only a few manufacturer nameplates remained, and those were not very readable. Seal leaks were common and various containers were placed under shaft extensions in the hope of containing the mess.
In 1999 I presented a paper at AGMA’s Fall Technical Meeting on a study we performed on the reasons gearboxes were sent to us for rebuilding. Only a small fraction of the “failures” were attributed to design issues. The vast majority were the result of poor maintenance and poor lubrication conditions.
It was impossible to predict the future of the gearboxes without knowing a detailed history. There is no national repository of data on industrial equipment like there is today for used cars. Some facilities record the history electronically; others write it on the outside of the housing with a paint stick. Either approach is better than having to say, “I don’t know,” in front of your boss.
That old FTM paper was reprinted in Gear Technology (May/June 2001) and is available in the archive or via the Beyta Gear Service website (www.beytagear.com) — at no charge. Sadly, it did not change the poor practices in mills around the country.