Gerhard,

On Fri, 20 Jan 2006 10:01:17 -0200, Gerhard Fiedler wrote:

>...
> whereas linear actuators
> have a similar screw gear inside that drives the output clamp (or whatever
> this thing is called that clamps around the screw gear, has a corresponding
> thread inside and drives the output).

"Nut" !  :-)

Or "drive nut".  In some cases it may be a half-nut so that it can be lifted off to remove the drive, such as 
on lathe feed-screws.

The type of rotary-to-linear motion convertor that I like is the "ball screw", where the screw and the nut 
have matching half-round helical grooves, which within the nut are filled with ballbearings, which 
"recirculate" as the nut moves along the rotating screw.  It acts like a really coarse thread (2 tpi isn't 
unusual), but with extremely smooth operation, low friction, and very little backlash.  The only disadvantage 
is that they are darned expensive!

Cheers,


Howard Winter
St.Albans, England


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