Consequences of Using 'N' Position in Automatic Transmission While Driving Downhill

Always and everywhere it is clearly written that you should not shift to "N" while driving, that it only serves to equalize the pressure between shifting from "R" to "N" and using it when stationary or, not recommended, for short and slow towing of the vehicle .

Why can't you use the "N" position when driving downhill?
What is the technical explanation for this?
What is the difference between driving downhill in 6th gear with engine speed 1100 -1200 rpm and driving in "N" with idle speed ~700 rpm?
What can be shortened or damaged?

When it comes to the automatic gearbox, I will not say anything, but at least two arguments speak in favor of not driving at idle, regardless of the type of gearbox:
- when driving downhill in gear you do not use fuel, when driving in neutral - you do use fuel (this does not apply to boxes with "free wheel" - there is no engine braking, so it doesn't matter if you are driving in neutral or in gear, the wheels never drive the engine),
- when you are driving at idle, when the engine stops, you will lose the brake and steering assistance, if you do not expect it (you will not notice that the engine has stopped), a very dangerous situation may occur.

Believe me, my friend, if you have an automatic in your car, it is already properly refined. And if you've decided on an automatic and you don't like the fact that you're always in gear, change your car.
I don't know how exactly it is in the regulations, whether it is mandatory to drive on a run, they do not teach that on the courses. So maybe that's why there's no such option?
As many manufacturers as many solutions, but I also suspect that you can drop from D to N without damage, worse with re-driving D.
In some cars, the manufacturer allows fanning in a limited range of gear ratios.

there is no such thing as a "freewheel" in an automatic transmission,
there is always a "box" spinning! only instead of a clutch there is a "hydraulic clutch" - the gears are shifted using valves (the car will reach the right speed / pressure in the gearbox and the gear change will click)
choosing
R - valves responsible for shifting forward gears are blocked,
D- blocked valve responsible for entering the reverse gear - only the forward pressure valves work
N - all valves are blocked / released and oil is pouring, no gear is engaged

and now answer the question: you can tow, but slowly!, as the engine runs at idle, the pressure does not harm the valves, when towing slowly, it does not harm, and with larger differences in revolutions, they can be damaged - if you have such a feeling, then try the car :)

I tried to explain it as simply as possible...

Well, I tried, the fuel consumption dropped by about 1.5-2 liters per 100 km in the city (engine 3.0). In general, there are no problems with shifting to N, there is no blockage, it loosens calmly, without jerks or any disturbing symptoms.
By pressing back to D, this is also done without jerks or strange noises, of course without pressing the gas pedal, the gearbox partially closes the converter, it reaches the engine speed and then closes to the end.
All such a fastening maneuver takes place in the range of 1100 - 1500 engine revolutions. I have no idea if it can harm the gearbox in any way. There is no mechanical lock to prevent it, so that's why I'm asking.

svavecone wrote:

I have no idea if it could harm the box in any way. There's no mechanical way to prevent this from happening, that's why I'm asking.

Maybe. After driving about 1000 miles, your gearbox will fail just like your friend - because he wanted to drive like a manual one (he put it in neutral at the traffic lights or on the highway from above) with a Toyota Camry ... Why did it fail? I do not know, I suspect that the effect of stresses in such a case is similar to that when leaving the snowdrift (front-back-front) - such beating kills the boxes at the moment. Thoroughly kills the torque converter (torque converter - this is the main clutch in the automatic transmission).
Driving on N? I do not recommend.

svavecone:
You are tired of this machine, change it. Don't torment him
Alternatively, share with us your impressions when something falls apart.
But if nothing happens, we'll see. Turn off the audio equipment, change the tires to eco, throw unnecessary kg from the car. You risk nothing, only advantages and it's for free

The converter probably has nothing to do with it, it should be adapted to carry greater loads/forces than the engine can provide. It always rotates in the same direction, so there can be no more overloads than it is designed for. Probably sooner the temperature and dirty oil could hurt him. As I wrote .... I do not feel any jerks during such a process, so there is no load on the converter, the gearbox first puts in the appropriate gear, as high as possible and calmly fastens the hydrokinetic clutch.

Theoretically, the load on the converter is greater when standing at the traffic lights in the "D" position, then you feel that it pulls non-stop, add to it the city traffic jam ... then you can argue that the rotors get on the butt (despite this, the converter should be adapted to this)

If anyone has a different, credible theory of using the converter in this way, please let me know.

I'm more interested in what happens then with the shields and the lubrication of the bearings between the baskets and the rollers.

Mr. "friend omniscient - ogur3k" I'm curious about the technical issue, many people ask me about it and I have no idea what to answer them, and I'm not going to give them morals similar to yours.

svavecone wrote:

Theoretically, the load on the converter is greater when standing at the traffic lights in the "D" position, then you feel that it pulls non-stop, add to it the city traffic jam ... then you can argue that the rotors get on the butt (despite this, the converter should be adapted to this)

Yeah, how many Nm does it carry at a standstill? Several ?
Throwing N in the machine while driving is absurd.

Well, that's the thing, since it transfers a few Nm at the intersection and you can feel it, and when changing to N or D while driving, you don't feel it ..... so where is the overload of the converter .....

Perhaps the type of gearbox is important ..... the one I tested was a 6-speed with tiptronic in a Peugeot 407 car.

The problem is lack of gearbox lubrication. When you throw N while driving, the oil pressure drops and there is no lubrication. So you shouldn't drive like that.

Have you googled buddy?
"The N position is also used when it is necessary to roll the car. The use of the N position in the case of short stops, e.g. at traffic lights, is not useful. The transmission control system is designed so that stopping the car with the brake pedal in the D position is sufficient and does not cause load the actuator systems of the gearbox in a way that would have a significant impact on excessive wear of the gearbox components.

The N position should not be engaged during continuous driving. The pressure system of the gearbox is controlled by the interpretation of many auxiliary functions. Driving speed, air throttle opening angle, torque and engine speed, the gear the car is in at a given moment have a decisive influence on the pressure values in the system. Disturbance of one of the functions controlling the pressure value in the system causes a rapid change of the work program as a result of the inertia of the control system as a function of time and has a very negative effect on the executive elements of the gearbox. "
Source
Then it describes what happens when the car is towed. Equivalent to riding on Neutral in total.
Can we find out what car this is? Because sometimes various miracles were performed by producers.

Forgive me, but I'm still dark and it means nothing to me.
In google you will find a lot, but are you sure that everything is up to date ... if I had no doubts, I wouldn't ask here.

TOWING IS NOT EQUAL TO driving in "N". In towing, only the wheels turn and the gearbox pump does not turn, so it is logical that there is no lubrication. When driving in "N", both the wheels roll and the engine runs, so the pump works constantly .

" "The pressure system of the box is controlled by the interpretation of many auxiliary functions. Driving speed, air throttle opening angle, torque and engine speed, the gear the car is in at a given moment have a decisive influence on the pressure values in the system. " "

The above applies to the pressure of switching gears and fastening the converter while driving, not the "N" position.

"The problem is with the lack of lubrication of the gearbox. When you put N on while driving, the oil pressure drops and there is no lubrication. Therefore, you should not drive like this."

So you're saying that there is no lubrication when the car is parked in the "N" position? So no basket rotates in the "N" position? Everything is disconnected from the pump and converter?
(the pump is permanently connected to the converter and rotates constantly, so is the bypass used so that the pressure on the baskets is completely at 0?)

I am asking because I am ignorant of the details and I prefer to understand it myself than rely on the words "because it is so" "because that's what the mechanics say".

I repeat:
"Maybe we'll find out what kind of car it is? Because sometimes manufacturers worked wonders."

You are worried whether the data in google is up to date, and we do not know if you are tired of a car from 2010 or 1970.
And don't cut out what suits you, just take into account the whole.

Throwing N while driving won't damage anything, nor will it help anything
The gearbox has lubrication so nothing will happen to it. That's why the automatic gearbox was invented so that you don't have to constantly "wake" and switching to N is, to put it mildly, slightly absurd

ogur3k wrote:

I repeat:
"Maybe we'll find out what kind of car it is? Because sometimes manufacturers worked wonders."

You are worried whether the data in google is up to date, and we do not know if you are tired of a car from 2010 or 1970.
And don't cut out what suits you, just take into account the whole.

I wrote a few posts earlier .... Peugeot 407 3.0, 6 speed tiptronic.
And I cut it out because I understand and confirm the rest.

Well, here's the first one who has a different theory than the rest. Maybe someone else will have this knowledge.

I do not know myself, but the mechanic with whom I made the gearbox (Automat from Safrana) explained that the brake should be pressed when the engine is running when switching to N. Something is changing with the pressure. He said that while driving, you only change between D and 1,2,3,4 to N, the brake must be pressed, not to mention R ;-)

If the engine is not running (see towing) it doesn't matter - you can switch to N.

And I got to this mechanic, because my friend, who was driving the machine for the first time, wanted to put it from D to N, but unfortunately he put it to R.
The car stopped and then started only in service mode.
He had to reimburse me almost 2,000 for the repair of the gearbox.

Starkes wrote:

because my friend, who was driving an automatic for the first time, wanted to put it from D to N, but unfortunately he put it on R.

He's a good guy... To change from N/A to R you have to press the brake and the lock button (which you don't need to do when changing from D to N and vice versa). So you have to consciously trigger both factors (presses) to do it...

I don't know, I've never tried
But are you sure it's like that in every ASB?

My cars with automatic transmission so far Renault Safrane, Rover 216 (CVT gearbox)
and currently Subaru Forester and Renault Laguna (tiptronic).

While driving, you can't turn on reverse - either you can't physically flip the lever, or the lever will go to R, and the gearbox will remain in N until the car stops.

Hucul wrote:

While driving, you can't turn on reverse - either you can't physically flip the lever, or the lever will go to R, and the gearbox will remain in N until the car stops.

Pole can
At very low speed (rolling the car) it is possible.

I won't try though.

Which does not change the fact that I recommend automatic transmission, but only a good gearbox with a good engine.

As for changing from D to R while driving is ridiculous, maybe the 1980 Cadet didn't develop it, but it happened to me in the '94 Ford Mondeo. While driving, I threw R and the car was idle, so you can't damage the gearbox in this way. It's different when driving backwards and suddenly throwing D, then the gear is engaged but after a while, then you have time to drive the gas to start with the so-called tire squeal, but it's not for that, but it's a protection, you also have time to suddenly stick brake to the floor to prevent damage. And as for driving on N, it does nothing, even when stationary or in traffic jams. When you're driving downhill, the gearbox is always in gear, it will never throw slack even if you were driving 2km downhill. Thanks to this, fuel consumption is lower, the car does not consume fuel during engine braking. I should get some kind of reward for that

I guess it depends on the type of box, the tested box I put in play while driving and it is actually in play. The gearbox normally brakes with the engine, which is why there are such differences in fuel consumption during idle descents.
It can reach 30-40 liters per month.

Because the event I wrote about

Starkes wrote:

And I got to this mechanic, because my friend, who was driving the machine for the first time, wanted to put it from D to N, but unfortunately he put it into R.
The car stopped and then started only in service mode.
He had to reimburse me almost 2,000 for the repair of the gearbox.

it happened like 8 years ago (or maybe even a bit more) I called this friend yesterday and he claims that he doesn't remember much, but I think he put it on P and not on R.
This, however, is of little importance what I wanted to convey with this post and I think it might be important for owners of ASB it
"...the mechanic with whom I did the gearbox (Automat from Safrana) explained that when the engine is running, the brake should be pressed when switching to N. Something with the pressure changes. He said that while driving you only change between D and 1 ,2,3,4 the brake must be pressed to N (while the engine is running) ..."

But I repeat that although I like ASB very much - I do not know about it and I will not experiment.

svavecone wrote:

The gearbox normally brakes with the engine, which is why there are such differences in fuel consumption during idle descents.

That's what engine braking is all about - when you brake with the engine, the fuel consumption is 0 (no injection control impulses), when the engine is idling, it burns even a few l / h.
I have a manual gearbox, but when I reach the intersection in front of which I have to stop, the computer shows 2l / 100km when driving in gear and about 7l / 100km when idling. I will add that it never shows less than 2l/100km, even when the diagnostics show that the injection time is 0ms.

It depends on the car. In Toyotas, you have 3.3l per 100km while driving downhill without gas, but standing at the traffic lights for about 10 seconds suddenly shows 35l. On the other hand, in Opel or VW it is 0l standing at the traffic lights and commuting in gear. I don't know about the others - I haven't been there.

Coming down a longer hill, engine braking fuel consumption is about 3.5-4 liters halfway up the hill at 70 km / ha after putting it into neutral 1.2-1.5 liters right away. Data from the on-board and combustion results confirm this. I guess every car is a rule.