What Did They Know and When Did They Know It?

Charles D. Schultz

President at Beyta Gear Service
Charles D. Schultz is President of Beyta Gear Service and one of Gear Technology's technical editors.

Latest posts by Charles D. Schultz (see all)

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.

Everything Old is New Again

Charles D. Schultz

President at Beyta Gear Service
Charles D. Schultz is President of Beyta Gear Service and one of Gear Technology's technical editors.

Latest posts by Charles D. Schultz (see all)

litvin-bookWriting a technical paper sometimes requires digging deep in your files for that obscure reference you just know you kept a copy of somewhere. I’ve been collecting books, papers, and magazine clippings for 43 years and remembering where things are after that amount of time and multiple job changes and relocations can be frustrating.

Even more frustrating is finding the sought after clipping and discovering it lacks the information needed to reference it in a peer reviewed paper. Contacting living authors is one thing; getting out the Ouija Board to contact others seems like a long shot.

An unexpected pleasure of this process is finding things I didn’t know I had. Such as a wonderful book (Development of Gear Technology and Theory of Gearing, NASA Ref. Publication 1406) by Prof. Faydor L. Litvin that included short biographies on people he thought were important to the development of gears. There is some impressive mathematical development early in the work that probably accounts for my forgetting that it was in my computer files. Included on that list of luminaries was the author of a book I had open on my desk at that moment, Prof. Earle Buckingham.

I have been a frequent user of Prof. Buckingham’s three volume master work, Manual of Gear Design. If you deal with epicyclic or planetary drives you too probably have pages 126-136 of Section Two memorized. I never bothered to look at other chapters in the book until prompted by another reference. It was a real shock to find that the Professor had taken the time to work out an entire system of high contact ratio gears back in 1935! While I had no illusions that I was breaking new ground with my Fall Technical Meeting paper, knowing that one of the giants of gear engineering had worked on the topic makes me sharpen my outline a little bit.

Have any of you had a similar experience in researching a new topic only to find that some of the hard work has already been done?

How Old is Your Machinery’s Handbook?

1928 Machinery's Hanbook

Title page and preface from the 1928 edition of Machinery’s Handbook

Machinery's Handbook, 29th edition

Machinery’s Handbook, 29th edition

Charles D. Schultz

President at Beyta Gear Service
Charles D. Schultz is President of Beyta Gear Service and one of Gear Technology's technical editors.

Latest posts by Charles D. Schultz (see all)


When discussing influential books on gears, I like to start with the venerable Machinery’s Handbook. No matter where you go in the industrial world you’ll find well thumbed copies of this handy reference book. My long time friend and noted gear engineer Ed Hahlbeck was fond of saying that if he was ever ship wrecked on a desert island he hoped his Machinery’s Handbook washed ashore too. I have a 21st century copy in my library right along side the 1928 edition I bought for a dollar at an estate sale.

The gear trade and general industry owe a big thank you to Franklin D. Jones and Erik Oberg for first publishing this reference in 1914 and for updating it every few years. Mr. Jones died in 1967 at the age of 88 but even the latest electronic versions still carry his name. He was a prolific writer/editor and I am a fan of two of his other books as well. Gear Design Simplified is a great guide for beginning gear people. The three volume Ingenious Mechanisms for Engineers and Designers is at the opposite end of the complexity scale but certainly shows the creativity of the people who worked in our trade before slide rules, calculators, and computer aided design.

I wonder if the publishers will have a special 100th Anniversary edition? Are there any other scientific or engineering reference books that have been in continuous use for that long? At one point I had a complete set of Gear Technology back issues but unfortunately they got damaged in one of my many moves. On line access to the contents diminishes that loss but I tend to agree with Ed; finding a Machinery’s Handbook is a good first step in resolving many shop problems.

Who Taught You About Gears?

Charles D. Schultz

President at Beyta Gear Service
Charles D. Schultz is President of Beyta Gear Service and one of Gear Technology's technical editors.

Latest posts by Charles D. Schultz (see all)

“The beginning of wisdom is calling things by their proper name” — Chinese proverb

Who taught you about gears? I was blessed with some great mentors in the early years of my career, but I never met some of my most important teachers. The answers to my many questions were “in the books” in the company library, I was told. Many a lunch hour was passed devouring the collected works of Dudley, Buckingham, and Jones. As I became familiar with the terminology, my co-workers and supervisors began to explain our company’s particular “take” on gear design. Some of the positions we took now seem a bit out of date, but I still use those same reference books today.

What is your favorite gear reference book? During the summer of 2013 I had the opportunity to inventory the library of one of my favorite all-time gear people, the late Don McVittie. He had many of the same reference books I own and many that I had never seen before. His family had donated the books to The Gear Works so the next generation of gear engineers would have access to them; a generous gesture from a guy who was always willing to explain things to an interested student.

If you are an experienced gear person, I hope you will share your knowledge with others. If you are just starting out in the trade, I hope you can find a good mentor. If mentors aren’t available, I have a suggested bibliography in my book An Introduction to Gear Design. The book is a free download from my company web site www.beytagear.com. The Internet has made locating even long-out-of-print gear textbooks easier, so good luck in your scavenger hunt.