"Peter Dohm" wrote

Torsional resonance can be extremely difficult to monitor andI am glad
that you were able to identify it before it became a dissaster. For the
moment, my own project and the decision to build around a PSRU or use a
direct drive aircraft engine has been pushed further into the future. But
I have wondered whether the elimination of critical speeds might be the
true purpose of those little springs in the driven plate of a manual
clutch.

I have read about the issue of whether to have ratios to get a constantly
different belt to tooth interface, and I wish I could remember more of what
it said.

I recall that while it is important to vary ratios in a toothed gear redrive
away from exact ratios like 2:1, so different teeth mate with both gears
(prevents wearing a certain pattern in each other) that is not a necessary
condition for toothed belt redrives. I recall that in fact, it is not
desirable to do that, but again, my recall is incomplete.

The information is out there, though.

I would love to design my own belt redrive, but when the time comes, I know
I would be more comfortable going with a company that has a well proven
track record with many of their drives in active, high time service.
--
Jim in NC