August 28, 2023
[starbox] No, I am not launching a criminal investigation. The title of this posting summarizes my ongoing study of the history of gear ratings. Most of you are aware that the American Gear Manufacturers Association (AGMA) was formed in 1914 by a group of gear makers who were concerned that the outrageous claims of some of their competitors were endangering the good reputation they were working to have with their customers. The gear trade has attracted some of the greatest engineering minds in history, but prior to AGMA there were no recognized standards for the things we take for granted today. Other “standards” groups pre-date AGMA because of their involvement with public safety. I will not go over the rash of boiler explosions, bridge collapses, and structure failures that prompted the need for better understanding of those fields of engineering. A gear failure was unlikely to be life threatening in the early 20th century, but AGMA’s founders foresaw a day when it could greatly interfere with the conduct of their business. They didn’t start the association in a vacuum either. Thanks to the Internet and modern technology it is possible to gain insight into the pre-AGMA days of the gear business. I just received a beautiful reprint of the American Machinist Gear Book, edited by Charles Hays Logue in May of 1910. Mr. Logue, formerly of R. D. Nuttall Company, set out “to make a book for ’the man behind the machine,’ who, when he desires information on a subject, wants it accurate and wants it quick, without dropping his work to make a general study of the subject.” His preface continues “Controversies and doubtful theories are avoided.” As author and editor, Mr. Logue relies upon noted experts for help in sorting out the topics. Wilfred Lewis, George B. Grant, and Percy C. Day are among those quoted. Engineering books dating back several hundred years are referenced in the very readable text. Many of the diagrams, drawings, and charts were very familiar from more modern reference books. So the preliminary answers to the questions posed in the title are: More than we give them credit for. And, Certainly by 1910. I look forward to making a detailed comparison of the 1910 rating methods and our 21st century procedures.