[TheForge] Re: Flatbelt excitement

[Mike Spencer]

Charles> My guess is that the problem is not over running, but is
Charles> probably a resonance issue.

I think it's both.

Charles> Given that the natural frequency of the belt system is
Charles> probably already pretty low, I expect that you need to find a
Charles> way to raise the natural frequency of the system.  Shorten
Charles> the belt which will raise the spring constant, or lighten the
Charles> flywheels, thus lowering mass moment of inertia.

Yes. Lightening the flywheels isn't a ralistic option.  I think the
problem would go away if I could get down to about 3 or even 4 feet
between shaft centers.  I can't do that without (A) completely
dismantling my truck powerplant and rebuilding it as a
stationary-mounted unit -- tedious and error prone -- or (B) cutting
down a tree I like.  Okay, so it's a completely dead and weathered
apple tree of no practical value that will fall down in storm one of
these years but I *like* it.  My wife likes it.  Ho-hum.  It may have
to go because the hammer sure isn't going to move.

Charles> Or you could raise the rpm-- it would flap a bit as you came
Charles> through the resonant rpm, but would settle down if you got
Charles> enough above it.

For largish values of "a bit". :-) That didn't work.  It never gets
past the maximal resonant range without flying off.  I actually saw
the belt momentarily standing off one of the pulleys on the contact
side as the wave passed around the pulley.

But yes, I'm sure your on the right track.  Thanks for the
obeservations.


- Mike

-- 
Michael Spencer                  Nova Scotia, Canada       .~. 
                                                           /V\ 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^