Originally Posted by Remeniz
So AWD has a center diff and 4WD doesn't have a center diff?
There's AWD, or 4WD(?), systems with lockable center diffs... and the front/rear diffs too, controlled by a computer to steer torque to the non-spinning wheels.
what you call a 'center diff' I call a 'transfer case', Unless there is an actual 'differential' in between the front and rear axles. That is something completely different.
The power from the engine goes through the transmission out to a intermediate case then out the back to the rear differential.
but the case has a offset front output yolk that is sent up the the front differential. Whats inside the 'case' is where all the magic happens.
Thou, thinking more about it, there is another configuration, in the above description this is assuming the engine is mounted in the traditional way.
With the engine mounted sideways, in some cases, there is no external transfer case. its built right into the transmission. The AWD Dodge Caravans are like this, the older ones anyway.
basically, AWD is built to run all the time. 4WD is not.