Centralny mechanizm różnicowy

[Dorr]

Witam wszystkich,

Jestem świeżym posiadaczem Patka i dopiero uczę się o nim, stąd moje pytanie. Wyczytałem na forum że w Pathfinderze nie ma centralnego mechanizmu różnicowego, stąd napęd 4x4 jest połączony na sztywno (proszę mnie wyprowadzić z błędu jeśli się mylę). A jeśli chodzi o tryb AUTO ? W jaki sposób wówczas komputer rozdaje moc na poszczególne osie ? I  brak międzyosiowego mechanizmu różnicowego w jaki sposób wpływa na tryb AUTO ?  

Dziękuję!

[Popeye]

Cytuję z anglojęzycznego forum, ale jak nie znasz języka Ang to zawsze można translatora użyć, powinno w miarę sensownie przetłumaczyć.

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The ATX14B adds "AUTO" to the above 3 modes, but also changes a bit how the 4H mode works. As before the ATX14B primarily drives the rear wheels, but it has a variable "wet" clutch pack driving the front wheels. "Wet" meaning the clutch plates are lubricated and cooled by the transfer case oil. This may seem odd, to add slippery oil to something designed to create friction, but the point is that because it's continuously variable and slipping ALL the time, as friction and heat is generated what wears IS the oil, not the clutch plates that would otherwise inevitably wear out and need replacement. Use Auto routinely? Be sure to change your transfer case oil as at least as recommended!

There are two hydraulic oil pumps in the transfer case which provide oil pressure forcing the wet clutch plates together as requested by the transfer control system. One is gear driven from the input shaft, the other electric to provide pressure when the vehicle is stationary and up to 34MPH. If you are set to 2WD the electric oil pump will not operate at all at any speed, which is the only and probably VERY small MPG benefit to 2WD. I'll test this some time for giggles...should be truly zero difference if driving over 34MPH.

Some have said that "AUTO" means power is only sent to the front wheels if rear wheel slip is detected, but this is not correct. Page 15 of the FSM Drive Line manual (http://www.thenissanpath.com/filelib/R51B/DLN.pdf) shows that power is transmitted to the front wheels based on *3* simultaneous and dynamic conditions. One is rear wheel slip, yes, but also more throttle input immediately sends more power to the front wheels. Also when braking hard and the ABS is operating, more engine RPM (engine braking force) corresponds to more power being transmitted, from in this case, the front wheels to the engine.

Also when at a stand still there is some amount of connection force from the wet clutch pack even at rest, and it's easy to test. Jack up one front wheel, chalk the rear wheels, set the parking break firmly, and shift the transmission into neutral. Set the transfer case to 2WD and try to spin the front wheel, easy as pie. Set the transfer case to AUTO and the front wheel is noticeably harder to spin. Set the transfer case to 4H and you can't rotate the front wheel at all anymore, same for 4Lo.

Now turn the engine OFF and do the same tests. With no oil pressure both AUTO and 4H spin freely as 2WD, while 4Lo maintains it's lock even with the engine off.

Now does the TX15B stay locked up in 4H even when the motor off? I don't know but would love to find out, and I bet it does if somebody can do the above test.

Also, does the ATX14B's wet clutch pack, when in 4H mode, provide enough clamping force to send 100% of the engine's power to the front wheels when a rear wheel is up in the air? I don't know, and not really sure how to test it conclusively... However there are various forum members who off-road the Auto transfer case without issue, and also the V8s have the even larger and stronger front differential from the Armada, implying they have designed the front of the drive line to take a lot of power from the transfer case. However ultimately I think it doesn't especially matter, if you're doing some rock crawling and getting wheels in the air I bet you're in 4Lo anyway which is unequivocally always locked."

 

Najważniejsze informacje są rzetelnie przedstawione.

Tu na naszym Forum też chyba był wątek o tym, ale nie mogę znaleźć teraz.