Quote:
Originally Posted by bruce.augenstein@comcast.
The classification of an automatic transmission depends on whether or not you have to shift it. If you don't have to shift, it's an automatic. I'd use all caps as well if I thought it would make this simple and obvious point any better.
Furthermore, just because automatics started with a planetary gear setup (and most torque-converter automatics still use this design), there's no reason to define the genre this way. As a for instance, are CVTs not automatics?
As a comment on lightness and efficiency, you're going to be hard-pressed to find a lighter, more efficient transmission than the automatic in the Toyota Prius.
Bruce
PS - You and I are going to disagree forever on this point, and also on your opinion of the "lossy nature" of an automatic. That's yesterday's news when you take a look at the current offerings. Probably the best evidence of this is that autos typically hold their own in the EPA ratings. Some are a little better, and some are a little worse, but they're certainly efficient.
|
Thats YOUR definition, but it's wrong. A manual transmission cannot shift itself, unless it has an outside source do so. SMG had a linkage not of cables, but of electrical wire, that sent instant signal from the driver to actuators that made the gear shifts for the driver when he triggered them. Since the actuators are physically shifting the transmission for you, it also feathers the clutch.
Once the linkage to the tranny was made electrical (instead of mechanical) you could have a mini-computer enabled to shift those actuators for the driver if they didn't want to shift themselves. Even though when in that mode, it shifts with no driver interaction, it is still 100% manual gearbox. A computer is doing the shifting.
In an Automatic, it works just the opposite. The automatic gearbox changes gears without driver interaction, and only when "sport mode" is engaged, is the driver able to over-ride/interfere and limit the shifts to only the gear he wants. Automatics have no clutch and arn't 100% mechanical but fluid driven and have torque converters.
Mechanically there are quit different, technically aswell. An automatic will shift with no outside source, it's uses hydraulics and spring valves, electro-mechanical servos..etc. Yet, the only oil in a manual gearbox is for lubrication.
Your doing yourself a grave injustice thinking an automatic in "sport mode" is the same thing as SMG or DSG...!
-Garrett
Post script: CVT's are neither, their CVT! Obviously, there are no gears, just gear ratios. No shifting, yet they way they are engineered to operate, by nature is automatic. Whats your point?
Also, under your definition, if you had your passenger shifting gears for you, that car now is an automatic..?