Just a thought here.

If the question is about a longish shaft that may support 'windup' torsional
vibrations, there are small torque sensors that can be clamped to a rotating
shaft that transmit their data wirelessly to a handheld display unit. Some
of these should have enough bandwidth to show the amplitude of any torsional
vibrations. This is a testing issue but it may allow the tuning of a
redrive and disclose any RPM bands that should be avoided.

bildan

"Mark Hickey" wrote in message
...
"Dan Horton" wrote:

Gordon, you got that? Please show us the "preload" that "will
compress only when torsional oscillations reach a certain amplitude".

I wonder if this might add something to the conversation:

http://www.international-auto.com/in...id=2600&cid=41

I recently bought an Alfa Romeo, and was intrigued to find one of
these in front of the first drive shaft (can't figure out why they
NEED two driveshafts on a short sports car, but that's a different
thread).

The transmission end hooks up with three bolts, the driveshaft with
the other three. Oh, and the metal band isn't there once it's
installed.

It seems to me that a device like this would probably give the effect
Gordon's looking for (since there's no "bottoming" of the spring, and
it's clear that the thing is designed to work in the power range we're
discussing (the Alfa Spider has around 120hp).

I'm guessing that this was added to the Alfa drivetrain to cure some
sort of resonance.

Mark "Mr. Flexible" Hickey