On Wed, 12 May 1999 09:07:45 EDT RBHouston@aol.com writes:
>In a message dated 5/12/99 12:23:23 AM Mountain Daylight Time,
>pasgeirsson@juno.com writes:
>
>> On top of that, the engine always
>> comes to rest, within a few degrees, in only two places. So the
>starter
>> always chews at the same places all the time instead of just random
>> places on the ring gear.
>>
>> Paul
>
>Paul,
>
>Please elaborate for the engineeringly challanged like me that can't
>figure
>out why an engine turning 1000 rpms or more would always stop in the
>same
>place.
>TIA
>
>Robert Houston
Hi Robert,
When you turn of the ignition the engine is usually rotating at its idle
speed of about a 1000 rpms, but then it starts to come to rest. It stops
pretty quickly because as it continues to rotae and slow down it is
working against compression in individual cylimders. Finally it come to
the last compression stroke that it can't get past and stops. At that
poni it will sometime rotate backwards a few degrees because the
compression is fairly high and the engine is really quite free to spin so
it rotaes back a small amount to the point of what you might call
equilibrium. That's the pont that it will usually be at rest. Doesn't
matter if it was piston 1,2,3 or 4 that it was compressing on. The
crankshaft in the car is designed so the thrust forces are always 180
degrees away from each other, so it will always come to rest in one of
two positions. There will be a few times it's a little off from its
usual resting point but that doesn't happen very often. Hence the
starter always engages the flywheel in about the same two small areas on
the ring gear
Hope this clears and not muddys the issue.
Regards, Paul
PAsgeirsson@juno.com
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