Our area has been “under construction,” or, more accurately — “re-construction” — for the past year or so. Every road in town has been ripped up; the old blacktop recycled; and the surface renewed with a fresh layer of asphalt; new handicap access curbs; and reflective striping. In less than 100 years, our expectations of what a “good road” is have gone from a graveled cow path to the well-lit, ultra-smooth secondary roads of suburban America.
The same thing has occurred in the gear trade. I had occasion recently to look at the “charts” of a never-used 1969 vintage turbo-compressor pinion. The client had to decide whether to use this precious spare part “as-built” or to spend time and money bringing it up to current standards. For those unfamiliar with turbo-compressor pinions, they run at speeds up to 60,000 rpm on very expensive oil film bearings, and have always represented the pinnacle of gear quality.
This particular pinion was certified to AGMA Q10 at the time of manufacture. In 1969, gear grinding was not yet widely used — especially on through-hardened parts. New charts, run on a state-of-the-art CMM verified that 45 year old claim, but the client wisely chose to have the pinion ground to current AGMA Q13 (A4) tolerances.
As much as we old guys revere the “good old days,” we must recognize that expectations are much higher today. Resurfacing a mile of four-lane highway once took a month of detours; we were complaining about a week of inconvenience (the road never actually closed to traffic). The improvements in machinery and method these days are incredible. The same is true of our gear shops; new equipment out-produces the old in both quality and cycle time.
The challenge for gear makers is to know when to invest in new equipment and when you can get by with the old stuff. Your customer isn’t going to settle for anything but high- quality end results. No one travels by cow path anymore.