Paul,

  Perhaps of interest...........

http://www.ringfeder.com/en/international/news-global/elastic-buffers-ordered-in-series-make-tschan-tnr-adjustable/



Kelly Troyer

  Yes that looks very interesting.

  Paul Lamar

  I REALLY LIKE that!

  Steve Brazil


Paul,

here’s a scenerio,,,,flying along with a ringfeder [flex coupling] on my
prop as a PSRU…..at about  4500 engine rpm…prop turning say
2250….elastomeric starts to wear out and the prop speed begins to
drop…..I divert and land…..taxi in and stop…..from what  see at the
ringfeder site I need some more elastomers and a wrench to pull off the
plate and prop and replace the elastomers. Put the front plate/prop back
on and start back on the flight.

Elastomers are small and light enough to carry a couple sets with me on
the plane and take along on the flight so I can replace them when needed

Is that too simple an explanation on what the ringfeder is doing for me?

Byron Head

It is under size for the HP you are trying to put through it.
Send us some pictures of what you have.

Paul Lamar


I am sorry (I know I've mentioned this before) but I fear
that some of the drawings of elastic couplings make me REALLY worried
about their ability to absorb enough energy.  Elastomers are NOT at all
"compressible", they are only "deformable".  That is, in order for the
coupling to do its job, each elastic component must have "bulge-room" in
order to absorb/release energy. It is obvious from forensic examination
of a car's suspension bushings that all the work is being done by the
bulging rubber around the edges.

The coupling illustrated in your last email is similar to one used on a
water-pump I once owned, but that was on a unit with an electric motor
and the coupling served to compensate mostly for alignment errors.

I fear that without providing room for elastomer deformation, or
drilling holes in the elastomers as you mentioned earlier, the coupling
would be essentially direct-drive; the drive-train could experience
sudden and early failure.

(Sorry for the empty email I sent earlier; my iPhone thinks it is
psychic and if I get my finger in the neighborhood the the screen thinks
I am about to tap "send" ... so I switched to my Linux machine"

R Berglund


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