Run away cars

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snipped-for-privacy@snyder.on.ca wrote:

Actually more vehicles use the CVT. My daughters Saturn Vue has a CVT, not sure if they all do? I think some other american made cars have them, but not sure. A lot of "maybes" here but I think the CVT has been used for some time now in sub compact foriegn cars not available for import to the US.
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wrote:

in Hybrid Synergy Drive.
There ARE CVT transmissions used in other hybrid and non-hybrid cats, but they use a metal belt and variable pully setup similar to a snowmobile drive system (or variomatic drive)
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On Fri, 12 Mar 2010 17:08:07 -0500, snipped-for-privacy@snyder.on.ca wrote:

Sorry, but your opinion cannot be considered to be a fact, just because you assert that it is.
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On Fri, 12 Mar 2010 19:39:37 -0500, snipped-for-privacy@dog.com wrote:

OK I WAS WRONG. On Hybrid Synergy Drive there is no mechanical lincage, but the shifter is a switch that controls power to the 2 motor-generator sets. Neutral dissables both , putting the car in neutral, without intervention by the computer. This meets the requirements of the law that the engine can be completely disengaged from the drive at any time.
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snipped-for-privacy@snyder.on.ca wrote:

Motorcycles have a switch on the handlebars that can be tripped to kill the bike in an emergency. It's convenient for a rider to flip it if he has to. This is in addition to the ignition switch. I think the one on my bike has the on position in the middle with an off position on either side. Are there any cars with an equivalent switch?
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On Thu, 11 Mar 2010 09:43:37 -0800 (PST), snipped-for-privacy@rochester.rr.com wrote:

Not true. The engine protects itself with a "rev limitter" which selectively miss-fires the engine to limit speed to a "safe" level by cutting out fuel injection (not spark)
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On 3/11/10 9:43 AM, snipped-for-privacy@rochester.rr.com wrote:

My 2008 Saturn is drive by wire and the computer does not complain or prevent me from putting it into neutral at any speed.
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wrote:

You forgot to add = "when it is working correctly"
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Why would he? The computer is not at all attached to the mechanical linkage of the transmission. It is built that way for a reason. I've never heard of anyone that could not shift into neutral, have you?
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You are assuming that his definition of "drive by wire" on his Saturn excludes the operation of the transmission. Maybe it does, but he didn't say one way or the other so we don't know.
> I've never heard

Surely you know there have been reports of exactly that by people experiencing the Toyota runaway problem. Are they telling the truth? Maybe not, but to just dismiss them outright without a complete understanding of how the transmissions are designed, actually work, perform under full throttle conditions, examining the transmissions from the runaway cars, etc, I'd say is premature.
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Yes, we do know. Linkage is mechanical.
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On 3/13/10 7:57 AM, Ed Pawlowski wrote:

I can't say either way for sure as I do not have the shop manual yet (no need for at least another 2 years). When the shifter is put in "M" manual while the transmission is in any gear other than 1st the transmission drops down a gear. If the car speeds up or down the transmission will continue to shift albeit a little more aggressively (a more sportier feel). If the shifter is put into "M" while the transmission is in 1st or stopped the car will not shift until you manually shift it with a toggle switch on the side of the shifter (sort of a clutch-less manual mode - where all 6 gears are available). It is this mode that makes me wonder as this has to be a by wire shift mode as there is no movement of linkage only the pressing (rocking up or down) of a toggle switch).
I know the computer plays a roll in the shifting because the shift patterns can be changed by reprogramming the computer. I believe there was a service bulletin for the 4 cylinder model that fixed a shift pattern problem on the smaller engine. The solution was uploading a patch to the computer.
From what I have read in a Saturn news group I believe the shifting is by wire from the shifter but can not say if it goes to the computer before the transmission or if the computer only monitors the transmission and has the ability to make adjustments to performance?
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Just as I thought. I don't know why some people want to rush to judgement without having all the facts. Obvioulsy there are a LOT of different cars out there and without factual data, no one here knows what exactly is or isn't in any of them.

Excellent example that things may not always be as simple as some people would have us believe. Clearly from what you describe, there is at least some kind of electrical control over the transmission.

Another excellent point.

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But you don't know what I know or what cars may be sitting in my driveway.

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On Sat, 13 Mar 2010 09:17:41 -0800 (PST), snipped-for-privacy@optonline.net wrote:

familliar with (which is quite a few) controls the shifting between forward ratios by switching hydraulic pressure with electrically controlled solenoid valves. Pre-computer controlled versions of the same transmissions used a hydraulic valve body which controlled the same hydraulic fluid flow by hydraulically opperated spool valves that balanced throttle and governor pressures against springs and each other.
Both types of transmissions, however, still have a "manual valve" which controlld whether the transmission is "engaged" or in "neutral", and whether it is in forward or reverse.. There may be some that also use a solenoid for reverse application as well the manual valve, but the interesting thing is, if you don't have the manual valve out of the neutral position, it doesn't matter what happens with the solenoid valves, the car isn't going anywhere. Also, it doesn't matter if the manual valve is in drive, if the solenoids are not actuated, and in the right pattern, the car isn't going anywhere.

The reprogramming changes WHEN the solenoids are actuated by requiring more or less governor pressure, or more or less throttle pressure to control the line (or apply) pressure.
Some "electronic controlled" transmissions only have electronically controlled governor and throttle pressures and still use a more or less conventional valve body.

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On Sat, 13 Mar 2010 10:57:24 -0500, "Ed Pawlowski"

And there are no selenoids or hydraulic controllers on or in the transmission in addition to the mechanical shifter? Does the shift linkage itself perhaps have external stops controlled by selenoids?
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I've never seen a transmission with a selenoid. Don't even know what one is. Not for neutral. Transmissions have lots of goodies that control shifting and take there information from the computer, but that is entirely different.
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On Sat, 13 Mar 2010 22:47:00 -0500, "Ed Pawlowski"

It might help if you at least knew what a selenoid was, and some of the things it can do when signaled ELECTRONICALLY. In your post above, you acknowlege they are there but don't understand them. It's thsoe "goodies".
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So, you say it is something like a SOLENOID? I know what they are
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On Sun, 14 Mar 2010 09:28:08 -0400, snipped-for-privacy@dog.com wrote:

SOLENOIDS do.
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