Subject: Time:11:57 AM
OFFICE MEMO Valve Springs Date:4/27/94
Someone asked if letting an engine sit undisturbed over the winter would cause
the valve springs to lose strength or take a "set". I didn't see anyone else
answer this, so I'll take a shot.
My answer is:
No, the springs would not be affected by sitting for months or even years in
one state of compression. They would not change the value of their spring
constant or "take a set". I checked three text books. Coil spring failures are
related to the number of cycles or times they are compressed, the force of
compression, and especially any flaws (nicks, scratches, rust) in the spring
wire, but not on the duration of one cycle.
If anyone wants to disagree, I'd be interested. Just quote your references.
My references:
1. Machine Design -Shigley & Mischke
2. Mechanical Engineering Design - Shigley & Mitchell
3. Marks' Handbook for Mechanical Engineers - Baumeister
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