JT McBride wrote:
> >The point is automatics generate more heat and heat is destructive,
> plus
> >adding an additional cooler offsets the reliability increase (to some
>
> >degree) by adding additonal components to fail. Automatics are more
> >complex and more sensitive to contaminants than Stds, Run an
> automatic
> >hard when it's 2 quarts low for any length of time and you'll be
> >visiting Aamco soon. Granted it won't do a std any good either but it
>
> >will survive much longer.
>
> Actually, automatics are far simpler, if you count only the torque-
> bearing parts. The hydraulic controller (that rats maze) is the
> complicated part. And I expect in 10-20 years a computer and servo-
> controlled valves will replace that.
>
> An automatic is a series of planetary gears, with a hydraulic coupler
> (the torque converter) driving it so the shifts are smoother. A manual
>
> transmission has multiple gears sliding on shafts, with the friction
> of the synchronizers controlling how smooth the shift is.
>
> As to contaminant sensitivity -- it seems to me the most sensitive
> parts
> are the wet clutches in an automatic (which also smooth shifts). There
>
> aren't too many wet clutch manual trannies anymore -- I suspect
> because
> they're not as reliable and efficient as dry clutches. Maybe someday
> we'll see dry-clutch automatics too.
>
> All-in-all, I don't think autos would account for 70% of cars sold if
> they weren't pretty darn reliable.
>
> Jim
>
> The PC 2nd Amendment: A well regulated population being necessary for
>
> the security of a police state, the government's right to ban and
> confiscate arms shall not be infringed.
> -- attributed to Vin Suprynowicz, 1995
Sorry to disagree but the torque converter and planetary gears are not
quite as simple as you make them out to be then add in all the parts of
the hydraulic control system (which is the most sensitive to
contaminants) and you have a fairly complex unit. Your counting every
gear in the manual and dismissing the 5 or 6 gears per planetary set.
The valve body is chock full of precision valves, ever take one apart ?
It would be interesting to do a parts count to the component level for
both an automatic and a manual.
KW
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:07:54 EDT