Re: looking for some gearheads

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@...> wrote:

> Some worm drives have an eccentric adjustment to vary the gear
> engagement. If the worm wheel is well-centered, you can bring
> the worm in almost to zero clearance. I did this on a very old
> dividing head, but that is probably built to tighter tolerance
> than a small gear reducer.
>
> Jon

At

http://www.winsmith.com/engineering/backlash.html

you can read:

"For those applications requiring near zero backlash for positioning or some other unique
situation, special designs which allow for backlash adjustment are usually necessary.
WINSMITH has developed two different designs to accommodate near zero backlash. One
concept uses eccentric bearing seats in the slow speed covers that allows for a center
distance adjustment when the covers are rotated. Although very close backlash can be
obtained, this method has a finite number of adjustments and is limited in its ability to
approach zero back-lash. In addition, it is only suitable for units with two slow speed
covers, curtailing its use. This method has generally been limited to units in the WINSMITH
C-Line.
A second, more recent concept named the S-Eliminator, uses a variable lead worm where
the worm thread thickness increases along its length. Backlash is reduced by moving the
worm axially (via an adjustment cartridge) until the worm thread thickness closely matches
the gear tooth space. This method provides infinite adjustment and can easily achieve near
zero backlash. In addition, as the gear wears in, the backlash can be easily readjusted in
the field using the built-in adjustment cartridge. This feature adapts well to the D-90 SE
product line and can also be adapted to the C-Line"

Steve