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Re: [ihc] 152/196 Flywheels & Harmonic Balancers
At 12:45 AM 7/4/04, JefGruwell@domain.elided wrote:
>In a message dated 7/3/2004 7:44:12 PM Pacific Standard Time,
>bearbvd@domain.elided writes:
>SV = Small V-8, which means the 266/304/345/392 V-8's.
>OK, Got it..
>"Bob weight" is a specific term referring to the technique used to balance
>any V-8 engine which has a 900 crankshaft design (as opposed to a 1800, or
>'flat' crankshaft design).
>OK. So that weight on my 304's harmonic balancer "the Bob Weight"?
>
>
>inline fours, inline sixes, straight eights, flat crank V-8'x, & V-12's do
>NOT need any bob-weight in order to balance them. (Although one should note
>that inline fours and flat crank V-8's are only in 'primary' balance, they
>have 'secondary' imbalances.
>
>Do not confuse 'bob' weights with counterweights--they look the same, but
>serve entirely different functions.
>And the weights that are 180 degrees apart on 152/196 Harmonic Balancers
are
>counter weights?
First of all, the term 'Harmonic Balancer' is really a mis-nomer. Should be
'Harmonic DAMPER'. Its function is to damp out harmonic torsional
vibrations in the crank. Sometimes (on external balanced V-8's) it ALSO
serves the function of carrying the external portion of the front
bob-weight, thus the confusion.
In order to do its job, the damper needs to have some rotating mass outside
the rubber damping ring. In the case of the fours, it needs to be neutrally
balanced. Quite why they might have used two symmetrically spaced weights
instead of a solid ring escapes me.
Counterweights are used to counterbalance the weight of each crankpin as
well as the 'big end' weight of the con rod mounted on it---and serve their
function best if located as CLOSE as possible to the mass they are intended
to counterbalance. The FUNCTION of counterweights is to reduce bending
stress in the crank, consequent loading on the main bearings, and,
likewise, stress in the block. Counterweights are NOT necessary to the
balance of an engine as an assembly !
As a for instance: your I-4 IH crank (like most I-4 cranks) has four
counterweights--one just to one side of each crankpin. Really high $$$$$ 4
cyl cranks tend to have eight counterweights--with one weight HALF as big
located on EACH SIDE of each crank pin. Think about this--doing it this way
reduces the bending on the crank even more, as the offset between the big
end weight and the counterweight is wiped out by making things totally
symmetrical.
Greg
>
>Thanks
>Jeff
>
>>Greg
>
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><META content="MSHTML 6.00.2600.0" name=GENERATOR></HEAD>
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><DIV>In a message dated 7/3/2004 7:44:12 PM Pacific Standard Time,
>bearbvd@domain.elided writes:</DIV>
><BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue
>2px solid"><FONT face=Arial size=2>SV = Small V-8, which means the
>266/304/345/392 V-8's.</FONT></BLOCKQUOTE>
><DIV>OK, Got it..</DIV>
><BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue
>2px solid"><FONT face=Arial size=2>"Bob weight" is a specific term
>referring to the technique used to balance <BR>any V-8 engine which has a
>900 crankshaft design (as opposed to a 1800, or<BR>'flat' crankshaft
>design).</FONT></BLOCKQUOTE>
><DIV>OK. So that weight on my 304's harmonic balancer "the Bob
>Weight"? </DIV>
><BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue
>2px solid"><FONT face=Arial size=2><BR><BR>inline fours, inline sixes,
>straight eights, flat crank V-8'x, & V-12's do<BR>NOT need any
>bob-weight in order to balance them. (Although one should note<BR>that
>inline fours and flat crank V-8's are only in 'primary' balance,
>they<BR>have 'secondary' imbalances.<BR><BR>Do not confuse 'bob' weights
>with counterweights--they look the same, but<BR>serve entirely different
>functions.</FONT></BLOCKQUOTE>
><DIV>And the weights that are 180 degrees apart on 152/196 Harmonic
>Balancers are counter weights?</DIV>
><DIV> </DIV>
><DIV>Thanks </DIV>
><DIV>Jeff</DIV>
><DIV><FONT face=Arial size=2><BR>>Greg</FONT></DIV>
><DIV></DIV></BODY></HTML>
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