
94 NASA RP–1406
3.16 History of the Invention of Double-Enveloping Worm-Gear Drives
The invention of the double-enveloping worm-gear drive is a breathtaking
story with two dramatic personae, Friedrich Wilhelm Lorenz and Samuel I.
Cone, each acting in distant parts of the world—one in Germany and the
other in the United States.
Initially, the author intended to find a photograph of Samuel Cone (1865–
1949), the American inventor of the drive that carries the name of Cone
Drive Co., the main producer of the aforementioned drives in the United
States. Unfortunately, the photograph disappeared from the company files
but was finally located in the family archives with the help of Cone’s
granddaughter Mrs. Mary Bell Kluge (nee Taylor). The search ended
happily, but it was not the end of the story because during our visit to the
Lorenz Co. in Ettingen, Germany, we learned that Dr. Lorenz had invented
methods to generate the worm and the gear of the double-enveloping worm-
gear drive and that he had received two patents for this work in 1891.
Dr. Lorenz’ invention was unknown to Samuel Cone, a modest draftsman
to whom the idea of a double-enveloping worm-gear drive came indepen-
dently, as seen in the following statement from the archives of the Cone
Drive Co. in 1924:
Even though such worm-gear drives were manufactured at the Lorenz Co.,
the value of Cone’s contribution cannot be diminished when one considers
his courage and strong will. Cone acted as a lone inventor whereas Lorenz
used the skills of his many employees. Still, it took a long time and required
much effort before the Cone drive technology became applicable in the
United States. We must pay credit to the Lorenz invention, but the father of
the American invention was Samuel I. Cone. Despite these facts, the
question of who should claim exclusive rights for the double-enveloping worm-gear remains unanswered. Our
opinion is that we have to credit both Lorenz and Cone.
Wilhelm Lorenz and Samuel Cone understood very well the advantages of the drives they had invented,
particularly, the increased load capacity due to the higher contact ratio in comparison with that of conventional
worm-gear drives. Although the geometry of the Lorenz and Cone drives differs, both types offer this advantage.
Later, investigations showed that the double-enveloping worm-gear drive’s higher efficiency results from the
existence of more favorable lubrication conditions.
The complex geometry of the double-enveloping worm-gear drive, the specific conditions of lubrication
(found later), and the formation of the worm-gear tooth surface as a two-part surface inspired many researchers
to develop the analytical aspects of the meshing of the worm and the worm-gear tooth surfaces. Among such
researchers are N. I. Kolchin, B.A. Gessen, and P.S. Zak in Russia, Sakai in Japan, and Litvin in the United
States, whose investigation and results are presented in Litvin (1968,1994).
The primary manufacturer of double-enveloping worm-gear drives in the United States is the Cone Drive
Textron Co. Presently, the Lorenz Co. does not produce these gear drives.
About 15 years ago, Mr. Samuel I. Cone of Portsmouth,
Virginia, manufactured at the Norfolk Navy Yard the
first Cone Type Worm. It is believed that this was the first
instance in which Double Throated or Double
Enveloping Worm Gears, having area contact, were ever
made.
Samuel I. Cone
Friedrich Wilhelm Lorenz