----- Original Message -----
From: "yummy" <yum@yermom.org>
To: "dml" <dakota-truck@buffnet.net>
Sent: Saturday, February 10, 2001 6:33 PM
Subject: DML: more spring rates..attn John
>A friend of mine mentioned that when calculating these things, you don't
> count the flattened coils on either end that give the spring a flat
> surface to rest on. Is this accurate?
Yes and no. Yes, if the spring has ends that are "closed", meaning that the
pitch (space between the coils) in the spring tapers off as it nears the end
of the part until the cut off end touches the coil next to it. The coils on
the ends are referred to as dead coils and are counted as part of the total
coil count but not the "active" coil count. No, if the spring has ends that
are "open" or pitch all the way through the end coils, then all of the
coils are considered active.
> If so, then these springs, being
> flattnened on the bottom only, have only _5_ coils, which I assume makes
> for an even higher and more unbelievable rate.
When I ran the first design for you, I made a mistake and entered it in as a
spring with 6 coils and closed ends and came up with a 511# /in rate.....
After looking at several suspension springs on the internet I noticed that
most of them have open ends. So I re-ran the design with 6 coils and open
ends:
With 6 open coils that are ground flat on the end two coils the rate is
409#/in, with 6 coils that are open and not ground the rate drops to 341#/in
>Do all manufacturers use
> the same spring steel in their springs? I hope so, otherwise the program
> is useless unless you know the alloy used.
I believe that most manufacturers use chrome silicone or chrome vanadium for
suspension springs. I also ran the design with several other common spring
steels and it doesn't make a difference.
Hope this helps, (and probably more than you ever wanted to know about
springs) :-)
-John
If you have any other questions feel free to e-mail me off the list at
jburgan3@home.com
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