Jim Prettyleaf wrote:
>On August 18 Greg Lund wrote:
>
>
>
>The TR6 crank problem is not the material
>but the small overlap due to the extremely long stroke.
>
>
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>I understand what overlap is when discussing cam and valve timing but would
>appreciate some information about what overlap means when discussing
>crankshaft vibrations and resonances.
>
It's a general term to describe the amount that the rod and main journal
circumferences overlap. The less those circumferences overlap, the less
stiff the crankshaft can be, and the more torsional vibration is
present. Very simply, it's a matter of beam strength in parts of the
crankshaft. The longer the beam--the longer the distance between the
rod and main journal centers--the more flexing of the crank under load
which causes large vibrational resonances, because the crank loads and
unloads, winds and unwinds, with applied force from combustion pressure
on the pistons.
Cheers.
--
Michael D. Porter
Roswell, NM
Never let anyone drive you crazy when you know it's within walking distance....
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