Think of it like this: The amount of effort applied to the ground by the tire on ice is the same effort applied to the ground by the tire on pavement. Neither tire can move the vehicle. When the effort required is increased to the tire on ice, an equal amount of effort is increase to the tire on the pavement.

 

I understand the physics of what is going on. But it's arguing semantics.

The entire point of having a 4wd system is for when traction is less than ideal. So a system that limits the ability to turn the wheels to drive the vehicle forward (or backwards) should never be framed as a "true 4wd", especially in the context of the OP question.

 

This is incorrect, open differentials send equal torque to both wheels. Locked differentials vary the torque applied to the wheels.

 

I really like that idea better than e-lockers because the TrueTrac is always "on" vs the e-locker that I need to turn on and remember to turn off. How do you like the TrueTrac? I have one in my Mustang but the project isn't complete yet.

 

There certainly are incremental improvements from the basic 2wd setup (as you know). 4wd with open diffs is still better than 2wd because you have all 4 wheels motivating you until something slips. When something does slip you have a better chance of finding traction and continuing to move. Traction control using the brakes is an improvement over the basic 4wd, and of course an e-locker, Torsen, TrueTrac, etc is better yet. Based on post 23 it seems the OP had an incomplete understanding of what the differences are so it's not all for naught. Next we need to figure out if a low range is required for "true 4wd".

 

Interesting how this discussion evolved. Think there is an attempted connection being made between what is "true" and what is more effective or better. Potential distinction between those terms in my mind. Also regarding locked diffs, I am trying to wrap my head around how in this case torque to each wheel would differ or vary. I think if it's locked torque would be equal.

 

On those truck with 10 speed and Snow/Wet mode shift control, there is something else that will happen to provide traction to one side over the other with the rear unlocked.
The ABS system is set to modulate the rear brakes side to side as each wheel losses traction.
You may not believe it until you try it next Snow opportunity. Works as good or better than locking the rear with the E-LOCK switch.
The advantage 99% of the time the rear of the truck will not slide sidewise like when a locked rear spins both wheel at the same time.
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It's an old time trick used on farm tractors that had separate brake pedal for each rear wheel when needed. Otherwise a bar across the pedals allowed both wheel to brake the same.
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In wet/snow mode, when rear traction is being modulated, the dash light will flash.
It is very fast and almost un-noticeable to the driver.
I have used this in 13" of snow getting out a 100' driveway up hill no less on well worn MS tires.
Made a believer out of me.
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There are two very good reasons why the E-Lock option is provided.
1. In off road crawling in 4wd low range first gear manual shift control you need both rear wheel locked in rough terrain..
2. Other wise for increased traction in other applications off road, on a temporary basis.

 

Its stated that the e-locker is for off road use only.
Its still a new time trick as well, as some new tractors still come with separate brake pedals.
A third reason I would add is its usefulness on boat ramps. I dont need, or even want 4wd. But for my hunting and for boat ramps the e-locker is a must have.

I did however just use it on the road the other day as we got hit with a nasty nor-easter storm that brought heavy snow. I turned it on to get up a hill.

 

Imagine a drivetrain that can provide a crazy amount of torque to an axle with a locked differential. You have one wheel that has crazy-good traction and the other has essentially no traction. Which axle will break?

 

@FX4Dennis i think traction and which tire breaks first is separate to discussing torque as it it sent to each wheel.