Re: [DML] Re: Diagnostic plug

["Ed Garbade" <edgarbade@xxxxxxxxxxx>]

The plans I have seen for a cruise control on our cars have a pickup coil
installed near the drive shaft with a magnet on the shaft.  This generates a
pulse in the pickup coil as the magnet rotates around the shaft which the
cruise control uses to regulate speed (ie. a pickup after the gearbox).

So I was thinking, the flywheel pickup could provide that pulse; however, it
would only be useful in a specific gear.  So if you set you cruise control
at 65 MPH in 5th gear, it would work fine on a flat surface and maybe minor
grades.  If you push in your clutch to downshift for a hill the cruise would
disengage anyway (right??).

I would think the automatic would be a problem since the cruise would not
disengage if the transmission downshifted.  My expectation would be for the
transmission to downshift on a hill thus increasing RPMs.  This would then
cause the cruise control to decrease RPMs to maintain the artificial speed.
More specifically since we are setting the "speed" using an engine RPM vs. a
wheel RPM the increase in engine RPM caused by the downshifting of the
automatic transmission would cause the cruise to ease off the gas to correct
our "speed" (thus slowing the car further).  So I don't think it would work
on an automatic (except on flat ground in a constant gear).

I do think this could work for a cruise control on a manual (assuming the
"pulse" was compatible).  Any thoughts on this?

Ed

----- Original Message ----- 
From: <mike.griese@xxxxxxxxxxxxxxxx>
To: <dmcnews@xxxxxxxxxxxxxxx>
Sent: Wednesday, October 27, 2004 2:30 PM
Subject: Re: [DML] Re: Diagnostic plug


>
>
> No, because speed is dependent on the gear the car is in.  The
> flywheel has no knowledge of that.  A crusie control pickup needs
> to be after the gearbox.
>
> --
> Mike
>
>
> -------------- Original message from "Ed Garbade"
<edgarbade@xxxxxxxxxxx>: -------------- 
>
>
> >
> >
> > Could this be used as a pickup for a cruise control?
> >
>





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