What exactly is tumbler gear mechanism?

Answer:
Also called Norton's mechanism, is a method of changing feed rates.
You can find it on http://books.google.co.in/books?ei=OauuT-vvKdHQrQeO6rCYBA&id=_wWET38FZqsC&dq=machine+tool+design&q=meander#v=onepage&q&f=false
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Contributor: Aditya
First answer by ID2097005310. Last edit by Aditya Aserkar. Contributor trust: 0 [recommend contributor recommended]. Question popularity: 26 [recommend question].