what happens if you go from neutral to reverse?

Nothing will happen. The car will remain in neutral.

 

<div class='quotetop'>QUOTE(stanlwyjohn @ Sep 8 2006, 09:01 PM) [snapback]316717[/snapback]</div>

Is that good for the "transmission" ?

 

Remember that the "shifter" is just a switch to tell the computer which direction you want to go, or to blow off excess forward momentum. You do something stupid, the computer catches your mistake.

As for cruising in neutral, there are lots of threads here about that. My advice is, DON'T!

 

The reason you don't lose speed as fast in neutral is that in neutral, MG2 is not recharging the battery. You can accomplish exactly the same thing by "dead-banding": touching the pedal lightly enough that you see no arrows into or out of the battery.

A very important safety reason for NEVER driving in neutral, is that in neutral you cannot accelerate in an emergency.

A less urgent, but still significant, reason for not driving in neutral, is that in neutral regenerative braking does not work, so if you do need to apply the brakes, you are losing all that energy, just as in a conventional car.

Conclusion: Driving in neutral is a very bad idea.

 

<div class='quotetop'>QUOTE(stanlwyjohn @ Sep 8 2006, 09:01 PM) [snapback]316717[/snapback]</div>

Remember in Ghostbusters when they crossed the streams. Something like that.

 

Supposedly the computer will deny your request and generate a beep. If that protection failed there would be a significant risk of mechanical damage. Suggest we all make our transmission 'requests for change" with caution.

 

<div class='quotetop'>QUOTE(daniel @ Sep 9 2006, 07:18 PM) [snapback]317190[/snapback]</div>

And it is illegal in most states.

 

<div class='quotetop'>QUOTE(tochatihu @ Sep 10 2006, 01:40 PM) [snapback]317414[/snapback]</div>

This is misinformed, but not exactly harmful advice. Advising more caution than needed doesn't really hurt.

The kind of failure this person is talking about would stop the car from working completely in any gear or speed. There is no failure mode where everything else works but now you can shift into reverse during forward motion and destroy the car. The car reverses by spinning an electric motor backwards. While in reverse, if the engine were to turn it would work against that electric motor and attempt to move the car forward.

http://prius.ecrostech.com/original/Unders...gOnAsIDrive.htm

So, bottom line, you don't EVER need to worry about accidentally bumping your shift lever at the wrong time -- except during safety-critical high-performance maneuvers, where you're already in serious trouble and need to do something drastic to save your skin. (In that unlikely case, accidentally shifting from drive to reverse won't actually hurt your Prius, but the runaway 18-wheeler that's about to rear-end you at highway speed will.)

 

<div class='quotetop'>QUOTE(mspencer @ Sep 10 2006, 07:44 PM) [snapback]317564[/snapback]</div>

Actually, the motor would spin MG1 as a generator, creating electricity which would be sent to MG2, which would drive the car backwards. Alternatively, the car could, at its discretion, spin MG1 forward to compensate for the forward rotation of the motor, so that MG2 could drive the car backwards on battery power while the engine continues to turn, without allowing the engine to work against MG2.

- Edited: MG1 would spin forward, not backward as I originally said.

 

<div class='quotetop'>QUOTE(mspencer @ Sep 10 2006, 09:44 PM) [snapback]317564[/snapback]</div>

My engine regularly turns (runs) when the car is in reverse. MG1 keeps it from delivering any torque to the wheels,and, when the batteries are low, it can generate electric power that can be sent to MG2. Remember that MG2 is the only one of the three motors that can turn the wheels backward.

 

Using neutral is *not* a "very bad idea". It's a perfectly fine
idea if used in an INFORMED MANNER, with full knowledge of subtleties
like lack of regen braking and being prepared to pop back into "D"
when needed. The laws about neutral-coasting are outdated artifacts
from bygone days when brakes were unreliable, and really need to be
eliminated.
.
_H*

 

<div class='quotetop'>QUOTE(hobbit @ Sep 11 2006, 12:11 AM) [snapback]317605[/snapback]</div>

Not exactly. California's "coasting in neutral" prohibition only applies to when going down a grade, which can still be hazardous, and is a bad idea at highway speeds.

Sec 21710 (CVC). The driver of a motor vehicle when traveling on down grade
upon any highway shall not coast with the gears of such vehicle in
neutral.

Nothing says you can't use neutral for "gliding" on level ground or when going uphill. I am not advocating it - I don't think it's a good habit and it is not the way the car is intended to be driven.

Edited to add: You might try to argue the technicality that even in "N" the Prius gears are never really in "neutral" if you define "neutral" as any of the gear being disengages. This is beacuse the Prius power combining gear set (what the call the "CVT") is fixed - it never shifts gears, nor shifts into or out off gear.