Previous blogs have discussed how fortunate we are to live in an age with the very best in gear making technology. Modern gear grinding machines can reliably produce whatever tooth modifications the designer can imagine. Gear materials have never been better; heat treating is no longer a black art. Finishing processes are available to make every tooth flank shine like jewelry. A while ago we had the opportunity to inspect some brand new gears that had been in storage for over forty years. These parts were “state of the art” when purchased and placed into climate controlled storage. The client could have used them with just a quick removal of the protective coating but wanted to make sure they met today’s quality standards. It was a real eye opener to see the inspection charts come off the modern CNC inspection machine. They matched the historical record; in 1968 the best quality available was “iffy” for what was then AGMA 390 Q10. Hours later, after a regrind on a CNC form grinder, the charts were several notches better and the client could rest easy on their reuse. Every process line runs on used gears. Those reground parts replaced components that provided forty years of excellent service. Hopefully they too will last that long. It raises the question though, how do we know our modern designs will actually be better than those they replace? There is a lot of affection for old cars, motorcycles, airplanes, boats, and farm equipment. People spend money buying them and even more money on restoring or preserving them. Except for a few pieces of lobby art I suspect our gear equipment is worked until the day it goes to the scrap dealer. One of the things I enjoyed about the gearbox repair and rebuilding business was the opportunity to see what designs stood the test of time. I am hoping to get the chance to check in on some gearboxes that I designed twenty five years ago to see if I applied those lessons properly. Don’t miss the chance to see how your creations are holding up.