1. Home
  2. Chevrolet 4x4 Trucks
  3. Autotrac Transfer Case (NP236)

Autotrac Transfer Case (NP236)

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.

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????

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?

Reply to
Roller
Loading thread data ...

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%.

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.

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

Reply to
shiden_kai

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.

Reply to
Roller

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.