Autotrac Transfer Case (NP236)

Thanks for the information. Do you have a good place to go to see an
exploded view and theory of operation?

Based on your explanation, the front ring and pinion is turning all the
time. If that is the case, why have a center axel disconnect at all? My
assumption was that the transfer case would not be turning the front ring
and pinion when in 2WD, when put into AUTO, the transfer case would lock up
long enough to spin up the front differential and lock up the center axle
disconnect and then the transfer case would unlock until slippage was
sensed.

You explanation is a simpler way, but you then have the drag of the front
deferential all of the time.


"shiden_kai" <v-l-m.TakeThisOut@hotmail.com> wrote in message
news:SdBpf.28759$2k.20592@pd7tw1no...
> Roller wrote:
>
> > Can someone send me a link to a tech site that talks about the NP236
> > transfer case? I would like to understand more about the autotrac
> > mode. My assumption is that in this mode, the front axel must be
> > locked up and the transfer case left unlocked unless the computer
> > sense slippage.
>
> You are correct, the front axle is engaged, but the transfer case is
> not totally unlocked. Most of the autotrak t/cases apply the clutch
> about 5%.
>
> > What I do not understand is how the transfer case gets into this
> > mode. Does it lock up for a period of time to allow the front axel
> > to lock up????
>
> The t/case does not have to do anything to allow the front axle
> to engage. The mere fact that the front drive shaft is always being
> driven slightly even in 2wd and the front wheels are turning, allow
> the front axle to lock up as soon as it's engagement is commanded.
>
> > Also, what kind of clutching does the transfer case have in it to
> > allow dynamic lockup? Does it just have syncros like the older
> > 241's? Or does it have some other type of cluck pack in it?
>
> It uses a large wet clutch pack that is for all intents and purposes,
> identical to an auto trans clutch pack. There is a large fork that
> is hinged at one end, with a roller bearing on the other end. THe
> roller bearing end moved the fork into engagement with the
> clutch pack by a ramped shifter which is moved by the encoder
> motor on the outside of the t/case.
>
> Ian
>
>
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