not my valve stem's keeper

[eschaider]

Thanks for posting that Chanmadd. I was looking for a similar YouTube vid to show just those dynamics. In the vid there are a number of dynamics at work. The two that are fairly significant are the sing's disposition to rotate in service (hence the street use value of the multi-groove locks) and also the secondary harmonic in the spring. It is the secondary harmonics that cause the wave you see in the video to propagate up and down the spring.

No matter what we do it is almost impossible to escape that moving wave. It is virtually identical to what we can reproduce using a slinky and our hands. Where the moving wave can cause us heartburn is when the frequency, the spring length and the wave velocity allow a reflected second wave to originate traveling in opposite directions to the first.

When they are exactly out of phase they are cancelling in their effect. As they start to come into phase they can literally break the spring when the phase of the two oscillations coincide and the amplitudes are additive. Assuming adequate energy in the two waves, the wave spring will break.

I want to say it was PAC springs that illustrated this on a Spintron but I can't find the YouTube vid anymore — although they have several very good other vids on YouTube.


Ed