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Precision Equals Performance at ZPE GripTec
October 12, 2022
While writing about the “degrees of connection” between current industry leaders and the giants of our trade, I wondered how many of our readers are familiar with some of those giants. Some have been “immortalized” through the use of their names on the formulas or influence factors they championed. Others founded companies that made an impact felt long after those particular firms stopped operating.
One of my favorite stories of my apprentice years, which I know I have told previously in this blog, concerns an unsung hero of gear rating development — Walter Schmitter of the Falk Corporation. Mr. Schmitter was long gone by the time I started my “time” at the Falk Corporation, so I cannot claim a “one degree separation” from him, but I did work for his son Bob Schmitter in the test lab, so let’s call it a degree-and-a-half.
The elder Schmitter began work under another gear industry giant — Percy C. Day — during the 1920s, and by the late 1930s he had risen to become Falk’s chief engineer. He was an active experimenter during the years “science” was being applied to gear teeth in an effort to develop a rating method everyone could agree on.
That consensus has, unfortunately, eluded us. But it was not for lack of trying. Walter is credited with the concept of a “stress parabola” for tooth bending and he built a giant gear tooth to “prove” it. By giant, I am talking about a single tooth that was about ten inches thick at the pitch line and probably fourteen inches in whole depth, with another twelve inches of metal so it could be cemented into a wall. Strain gages were glued to the artifact and loads were applied with a roller mounted to the fork of a lift truck. Hundreds of data points were collected and analyzed to develop the theory.
The dimensions are only approximate because the artifact no longer exists. It was uncovered during a routine clean up in the test lab by a green kid — me — who asked his supervisor what it was. Said supervisor said “It was a test piece my old man played around with to develop a formula with AGMA.” I foolishly assumed it would go to a place of honor in our display case; instead I was told to dump it in the scrap hopper for the foundry to remelt.
It felt wrong then and still feels wrong today. Not just the destruction of the artifact but the lack of recognition for a person who helped advance our understanding of gear strength in a way that still plays a big role today.
