F. George McDuffee fired this volley
in :

On Thu, 26 Jun 2008 00:37:41 -0400, "Tom Gardner"
wrote:

I want to turn a 4" OD x 3/8" thick gear 80 to 110 degrees in 100 ms.
I'm thinking of a 4" stroke by 1-1/4" bore air cylinder attached to a
rack gear that would engage the round gear. No, I won't do it with a
servo! I'm thinking a 1/2" round rack gear in a tube with Thomson
linear bearings and a scallop cut in the middle of the tube to expose
teeth to the round gear. This seems simple and cheap. In fact, it's
so simple it would seem that it should be an off-the-shelf item! I
just assume it would be easier to do with round rack than square rack.
Is this available or did I invent a new wheel?



Tom, we have an almost identical device feeding time fuse for cutting.
The assembly consists of a one-way drum clutch inside the feed tire,
moved through a portion of a revolution by a crank rod on the clutch
whose outer end is moved an air cylinder. It moves the fuse from 1/2" to
4.10 inches per stroke, and has nearly zero backlash (for accuracy).

I think that setup is simpler yet than what you described, and does
exactly the same function -- precisely and repeatedly for years without
any maintenance.

LLoyd