"hunting tooth" sprocket / chain

[sparky mark]

  Just wondering if this was a patented invention or not.
  "With a double-cut sprocket, the tooth pitch is half that of the chain. Therefore, the number of effective teeth is half the number of actual teeth. If the sprocket has an odd number of teeth, the number of effective teeth is fractional, and each tooth engages the chain only on every other revolution. This cuts tooth wear almost in half, nearly doubling sprocket life. The same is not inherently true for sprockets with even numbers of teeth."
  My model "E" CLETRAC had an odd number of teeth on the sprocket. I believe that the CAT model "60" also had an odd number of teeth on the sprocket.
  Seems like a very clever idea.
  Did all CLETRAC models do this? Did most manufacturer of tracked tractors do this?
Thanks in advance for any replies.

[Robert Barbour]

All of my crawlers have the double cut sprocket with an odd number of teeth except my 1940 D8, some of my Cletrac's go back to the thirties. If that idea was patented the patent has long expired. it is common practice today.