[Land-speed] Inertia Activated Fuel Cut Off Swiches

Jon Wennerberg jonwennerberg at nancyandjon.org
Mon Jun 8 05:39:25 MDT 2009


On Jun 7, 2009, at 7:54 PM, drmayf wrote:

Always the one to try and be safe, I see in the 2009 rule book that  
inertial switches for fuel cut off are going to be required for 2010.  
So I purchased one from Pegasus racing thinking that they sell stuff  
used by the formula ford cars and SCCA cars as well. Well it came  
yesterday. Kinda spendy for such a small part. However, I am surprised  
at just how easy it is to trigger. If I have it in my hand and just  
briskly wave that hand around, it will trigger.  AN dof course, it  
triggers when I hold it with one hand and bump with the other.  I am  
really thinking that this particular unit may trigger in just a simple  
spin or near spin.  Of course I guess I could mount it right on the CG  
and just a rotation of the unit woudl occur. The insructions for sure  
say not to mount it on a panel which can vibrate as that will trigger  
it.
My questions are manifold. Are there going to be, if anyone knows, any  
kind of spec for these items? I would think that someting akin to an  
SFI spec is needed here. If a simple piece of foam requires it, then  
someting that might prevent a large fire should also need a spec as  
well. We have approved fire extinguishers why wouldn't this also need  
some kind of at least generic approval.
Next question, for you folk that have these already installed. How  
much of a wiggle or impact did it or does it take to trigger yours? It  
may simply be that it is working fine and that I can move it fast and  
hard enough to trigger.

I have sent the company an email asking what kind of g levels or just  
motion  it would take to trigger it under normal or not normal  
circumstances. When I get the answer, I'll post it.

Yes, I know that I could have gone to the junk yard and bought one. So  
exclude any comments about that please. As the same questions  
apply...what are the trigger levels....


comments?

mayf
_______

Mayf, I think that I remember this specific subject being given a  
thorough discussion on the Forum over at landracing.com.  I think that  
the consensus was to go to the junkyard and take one out of a  
relatively recent model Ford car (specifics elude me so early in the  
morning).  I'll see if I can find the thread.

The sensitivity of the switch versus the "bump" from the push vehicle  
was a big issue -- and the store-bought varieties, such as yours from  
Pegasus, didn't appear to meet the needs of "our" real world needs.


       Jon Wennerberg
Tall guy with moustache
and a pair of 2 Club hats


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