<VV> Rod caps and balancing
John Kepler
jekepler at amplex.net
Wed Jun 11 21:47:10 EDT 2008
"This is why the 'Vair crank has no counterweights."
What crank are you looking at????? The 140 crank I have sitting on the
bench in from of me sure as hell has "counterweights!
"If the pairs of rods shared a journal, the crank would MANDATE
counterweights or the engine would rattle itself out of the engine bay in
short order."
Do a Google search on: "Secondary imbalance" and "Tertiary imbalance". Just
because you balance and counter-weight the crankshaft, doesn't mean the
engine won't vibrate like a rock-crusher. An in-line 4-cyl has a tertiary
imbalance that causes the engine to want to oscillate "up-and-down".....a
V-6 wants to oscillate "side-to-side" along a axis parallel with the
crankshaft.......V-4 have a weird pivotal movement along a vertical axis
perpendicular to the crankshaft (because it has secondary, tertiary and
quaternary imbalances that give it more moves than Vegas Pole-Dancer!).
There is NO way to get rid of these secondary and tertiary imbalances
passively/statically. The only way to get rid of them is to mechanically
counteract them with specific counter-rotating balance shafts.
The geometry of a flat opposed 6 makes it inherently devoid of any secondary
or tertiary imbalances, so it's an inherently smooth, low-stress engine.
John
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