On Wed, 1 Feb 2017 12:47:59 -0800 (PST)
" wrote:

Yes. The pulley halves move in and out so the belt goes up and
down. Increases or decreases the size of the pulley. Reeves drive
is what that thing is.

i think i have seen these in delta lathes

did not know they were called reeves drive

interesting approach

does it require adjustment from time to time