[DeTomaso] More cruise control issues

[MikeLDrew at aol.com]

In a message dated 8/31/09 10 05 56, chrisvkimball at msn.com writes:


> It seems to me the RPMs would register speed exactly like the drive train 
> would, the faster you go, the faster the RPMs in any given gear.  Keeping 
> the RPMs constant would naturally keep the speed constant, too, so  I see 
> no reason why some kind of signal from the tach wouldn't work as a speed 
> signal.  Any thoughts?
> 

>>>Uh....what?

Your theory is correct assuming you have a one-speed car.   There is a 
direct correlation between speed and RPM.

But for the purposes of a cruise control that uses actual vehicle speed as 
an input, in a car that has more than one forward gear, RPM is less than 
useless....

Mike