I was being facetious, but now I want a picture.
On Thu, 11 Sep 97 10:07:39 PDT rpalmer@ames.ucsd.edu (Bob Palmer) writes:
>Ray,
>
>Since I brought this topic up, maybe I should try and answer you. As
>Brock
>Tella says, I should probably draw a picture, but let's see if I can
>make do
>with a few choice words.
>
>The effect of rod length has to do with the relative effect of the
>side-to-side motion of the crank rod throw (or offset as you call it).
> If
>the rod were infinitely long relative to the radius of rotation of the
>rod
>journal on the crank, then the piston would exhibit simple sinusoidal
>motion. With decreasing rod length, the side-to-side motion becomes
>more
>important and tends to pull the piston away from top dead center
>faster and
>faster while also keeping the piston near bottom dead center longer.
>For
>typical rod length to stroke ratios around 1.7:1, the piston spends
>quite a
>bit less time around top dead center than around bottom dead center.
>
>The assumption in this discussion is that cylinder volume is kept
>constant
>for different rod lengths by changing the pin position in the piston.
>
>Hope this helps.
>
>Bob
>
>>
>>Gentlemen,
>>
>>I am a layman and not an engineer, but I have been reading this
>thread with
>>some interest. Now though, I feel compelled to ask a question
>(albeit
>>naive it may be). So please educate a few of us.
>>
>>You all keep talking about rod length dictating compression, torque
>and
>>piston speed, but if the crank offset (correct term?) does not
>change, then
>>why would piston speed and travel change? All I can see is that
>longer
>>connecting rods would reduce cylinder volume, but piston travel and
>speed
>>would remain constant.
>>
>>Is that not correct? If not, why?
>>
>>Regards
>>
>>Ray
>>
>>
>
>
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