Re: REFLECTOR: Bearing AD (Duane Swing)

["James F. Agnew" <Jim_Agnew@ibm.net>]

DAlexan424@aol.com wrote:

> In a message dated 2/3/99 1:06:48 AM Pacific Standard Time,
> aegerter@dataway.ch writes:
>
> > >>    Scott and I have been looking at the front bearing support and are
> >  >> working on a solution.  One of the problems that any wide area washer
> > type
> >  >> retainer or the reversal of the bearing in the holder, or even the
> >  >> replacement of the countersink screws with standard flat head screws, is
> >  >> that unless the control stick is restricted from being pulled back
> > further
> >  >> than the full down elevator will allow (26 degrees) the possibility of a
> >  >> total bearing failure or the attach aluminum bracket breaking as a
> result
> >  >> of constant flexing is still an issue.
> >
>
> There are bearings called dual row radial type that allow for a certain amount
> of axial mis-alignment. They look to have two rows of captured ball bearings
> in a race that is slightly concave. But the true problem as I see it in my
> mind is that the control linkage travels in a slight arc from mid position
> when moved anywhere from neutral. It would seem that some type of "scotch
> yoke" assembly may allow the control lever arm to move in its necessary arc
> while enabling the actual sliding mechanism to be free to prevent binding and
> side loads from mis-alignment. This of course would only add about 10 more
> items in a critical failure path, but may help to illustrate what the problem
> may be. Up to now, we have been relying on the flexure of the aluminum tube to
> "allow" the current system to work.
>

Actually Dale, I don't think the torque tube has to flex, the rod ends on both
ends of the elevator push tube should absorb most of the mis-alignment.   In fact,
I have told Scott that there is no good reason that I can find for extending the
tube all the way to the opening in the top of the keel.  The bearing could be
located on a bracket attached to both sides and the top of the keel just in front
of the stick opening.  To fix the possibility of backward movement of the torque
tube a simple collar in front of the mid bearing would add a lot of safety factor.

Jim


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// Tampa, FL
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