What is 4X4 Auto?

[shadowless127]

some people here are confused.

While i am aware AWD and 4WD or two completely difference systems, I was simply implying Auto 4x4 from a theoretical, not mechanical standpoint, is similar to AWD because when you're in Auto 4x4 there's no user interaction required to engage the system.

 

[ummduh]

ummmduh; ControlTrac is not the AWD system, it's the 4WD system. We are aware that the AWD is a viscious cluth system. And AWD is good for a lot more then bad weather; depending on how stuck you get, AWD would actually be more beneficial then 4wd; If you have one wheel badly stuck, having 4wd engaged would probably suck as all the power would be transfered to that one wheel. With the AWD system putting power to the other 3 wheels might make it easier to escape.

Sorry about the confusion. I assumed the controltrak was the awd version. My 4wd Explorer has no badging either way.

Anyways, the explorer AWD is not capable of this feat. Subaru and other various systems are, but they have active differentials front and rear that can control what power goes where. In the Explorer you can get a limited slip (a passive traction aid, it does not react to the situation.. it always does what it does no matter what) in the rear and the front is always completely open, with NO means of controlling left/right distribution. The transfer case is only able to control front and rear output shaft torque, not individual wheel torque.

Some newer traction control systems can use the brakes to stop the free-spinning wheel so that power gets to the wheel on solid ground, but this has nothing to do with awd or 4wd.

Furthermore, 4wd gives equal torque to the front and rear differentials no matter what. (your "one wheel gets all the power" statement being not true)

 

[ummduh]

some people here are confused.

While i am aware AWD and 4WD or two completely difference systems, I was simply implying Auto 4x4 from a theoretical, not mechanical standpoint, is similar to AWD because when you're in Auto 4x4 there's no user interaction required to engage the system.

Well it is and it isn't.. which is why the confusion exists. It is, as you don't have to think about putting it in 4wd normally. But it isn't because it doesn't send any power to the front until the rear tires slip in the first place, whereas the awd always sends the 35% or whatever it happens to be in the Ex frontways whether it needs it or not.

And then there is the last gen explorers that had 2wd, auto 4wd, 4wd high and 4wd low.. I think that was a better solution.

 

[GJarrett]

People.... this question was answered NINE YEARS AGO on this forum by a member named Tom Wilk. Check out the second post of that thread which should give you a fairly clear explanation of just exactly what is happening while you're in 4 auto.

http://www.explorerforum.com/forums/showthread.php?t=10166

 

[gijoecam]

People.... this question was answered NINE YEARS AGO on this forum by a member named Tom Wilk. Check out the second post of that thread which should give you a fairly clear explanation of just exactly what is happening while you're in 4 auto.

http://www.explorerforum.com/forums/showthread.php?t=10166

Good to know, but we already re-established that here in this thread... and it's irrelevant. The discussion took a turn with shadowless trying to explain some 'theoretical' explanation of why the automatic 4 wheel drive system is the same as the all wheel drive system... I still don't get it...

-Joe

 

[GJarrett]

I don't either... so I thought that might clear something up, because they are not the same. I guess I'm not too good staying on subject when the subject changes, LOL. I was replying to the title subject after reading about a dozen replies, all of which were wrong. If anyone on this thread really wants to know the answer instead of spouting a bunch of opinions and theories, they can read the link I provided, and gather an additional hint from heathmo's reply in this thread that confirmed power to the front even without rear slippage. Sorry if I confused the thread with facts answering the original question.

Oh well, I'll go on to other things ~

 

[Donner]

This thread...

OK kiddies...play nice or I'll be forced to pipe Barry Manilow into your pc speakers..........

JDraper, this thread had two purposes: 1 - WHAT is 4x4 Auto; 2 - HOW does it function (both technically and opinion). It went down hill for no reason... And for anyone to blame Shadowless is absurd.

 

[Russ in CT]

There is a multitude of vehicles out there that are marketed with the term 'AWD', but are predominently 2wd, applying power to the other 2 wheels only when slippage is detected. Sometimes the predominantly driven wheels are the front 2, sometimes the rear 2.

Other vehicles that use the AWD moniker always drive all 4 wheels all the time.

I used the term 'part time' AWD to drive home the point that not all AWD systems are really driving all the wheels, all the time. I think 'full time' AWD and 'part time' AWD makes the distinction quite clear. While these might not be industry standard terms, I think something like them should be. To the average consumer, they see AWD, and they don't even know to ask any more than that.

 

[Four0Sport]

opintions often get misunderstood.. i see what shadowless is saying, auto 4x4 acts like awd in the sense that you dont have to worry about selecting 4wd when you lose traction, the truck does it for you. other than that 'idea' awd and auto 4x4 are as different as night and day. ive owned a 4x4 auto EB that my sister now drives since it will automatically engage 4wd for her when she needs it, alot different than having to get out to lock the hubs on my 93 and place it in 4 hi, and totally different than my 97 awd which requires no thought process whatsoever when driving in inclement weather other than 'slow down'. hope this helps!

- Jack

 

[gsmaclean]

OK, to recap (seeing as I started this thread), this is what I've figured out from what I have read here and elsewhere:

2WD = rear wheels drive only

4WD High = All four wheels receive power, no center differential, usable on mud/snow only

4WD Low = All four wheels receive power with reduction in the transfer case, no center differential, usable on mud/snow only

4WD Auto = 2WD unless truck detects slippage between front and rear wheels. When slippage is detected, truck starts engaging 4WD clutch in transfer case on and off quickly to send power to the front wheels as well. Clutch is cycled instead of just engaged continuously to allow for front wheels to travel further in turns on dry pavement without binding up the driveline, due to a lack of center differential. Duty cycle (time clutch engaged vs time clutch disengaged) varies - with lots of slippage between front/rear wheels, clutch spends more time engaged. As traction improves, clutch spends more time disengaged.

Control-Trac = 4WD Auto, but the truck can also apply brakes to individual wheels that may be slipping to direct power to wheels with traction. This is in lieu (or in addition to) limited slip differentials.

Advance-Trac = Control-Trac with the ability of the truck to apply brakes to individual wheels to assist with skids and avoid rollover situations.

AWD = Means anything the manufacturer decides it means. Can mean:

All power sent to one set of wheels until slippage detected, in which case some torque sent to other set of wheels (i.e. Honda CR-V)

All power sent to all four wheels simultaneously through limited slip and/or lockable center differential (i.e. Subaru)

All power sent to all four wheels simultaneously through viscous coupling

Any other system that sends power to more than just two wheels.


Does that sound right?

 

[heathmo]

Yep

As has been stated, no the 4x4 in the ControlTrac system is NOT like AWD in the sense that AWD has the ability to have all wheels driving the vehicle because of a differential in the middle, which in most SUVs I've seen w/ that feature can be locked to allow full 4wd like you'd find in any normal truck, causing the front and rear to spin at the same rates. The ControlTrac in its operation may seem more like AWD because of its automatic engagement of the electromagnetic clutch. Which based on all this info basically is always slipping. There is always an amount of power being transferred to the clutch (the brown wire). How much is determined by the GEM and you. A lighted switch with the BWM will show you what I'm talking about. when you lock 4x4 high it's giving the clutch full power, and it gives it full power when you stomp on the gas as well.

Personally, I like the choice of having it on or not, although there is something to be said for the traction of AWD in inclimate weather. Yes, I've driven older 4x4 styles with the manual locking hubs, which in essence is truly how 4x4 works, even auto locking hubs are closer than the ControlTrac design. Granted my stepdad's old Bronco did have push button 4wd, it required hopping out and locking the hubs in. The late model Explorers also have live front axles, which means that the front wheels are always connected to the differential, no free wheel spin. I know that at least from the 2nd gens on that's how they were set up.

But it goes to show you how the Explorer stayed America's #1 selling SUV, by pandering to the lay person who knew little about true 4wd and off-roading. It keeps them safe enough on the road because it automatically kicks in 4wd when they need it, and turns it off when they don't, they never notice the difference. Kind of like AWD, but definitely not the same.

I personally think it's kind of a dumb idea, I like having the choice of 2wd or 4wd, unless I buy a vehicle specifically because it has AWD. I know when and how to use it, I don't need a computer trying to figure it out for me. Plus I would think it would be hell on your clutches to be engaging and disengaging so often. Just my two cents.

 

[heathmo]

Posted before I got a chance to get mine up, you're pretty close, the ControlTrac, doesn't do braking in the old versions of the Explorer ie 2nd gens, not sure if that changed in newer versions, but all in all, pretty much exactly right.

 

[Albino 94LTD]

OK, to recap (seeing as I started this thread), this is what I've figured out from what I have read here and elsewhere:

2WD = rear wheels drive only

4WD High = All four wheels receive power, no center differential, usable on mud/snow only

4WD Low = All four wheels receive power with reduction in the transfer case, no center differential, usable on mud/snow only

4WD Auto/Control-Trac = 2WD unless truck detects slippage between front and rear wheels. When slippage is detected, truck starts engaging 4WD clutch in transfer case on and off quickly to send power to the front wheels as well. Clutch is cycled instead of just engaged continuously to allow for front wheels to travel further in turns on dry pavement without binding up the driveline, due to a lack of center differential. Duty cycle (time clutch engaged vs time clutch disengaged) varies - with lots of slippage between front/rear wheels, clutch spends more time engaged. As traction improves, clutch spends more time disengaged.

Advance-Trac = Control-Trac with the ability of the truck to apply brakes to individual wheels to assist with traction.

Advance -Trac with RSC = adds gyro's to the system. When it detects excessive body roll, it applies braking force to individual wheels to prevent roll-over.

AWD = Means anything the manufacturer decides it means. Can mean:

All power sent to one set of wheels until slippage detected, in which case some torque sent to other set of wheels (i.e. Honda CR-V)

All power sent to all four wheels simultaneously through limited slip and/or lockable center differential (i.e. Subaru)

All power sent to all four wheels simultaneously through viscous coupling

Any other system that sends power to more than just two wheels

Control-Trac is 4dw Auto

Advance-Trac doesn't detect roll-over. The Advance-Trac w/RSC does (Roll Stability Control).


Edit; is this horse dead yet?

 

[Donner]

Close enough...

Almost... Just toss out the Owner's Manual.

 

[gsmaclean]

Almost... Just toss out the Owner's Manual.

That useless bit of non-information in the manual is what caused me to start this thread in the first place!

My 94 Limited's manual was extremely detailed, had lots of maintenance information, and was basically full of useful information.

My 03 Limited's manual basically says "you're not smart enough and don't need to know about this, so just turn the key and drive."

 

[Donner]

So, now you know... What will you do with all of the information provided? What will change on your 03?

 

[gsmaclean]

So, now you know... What will you do with all of the information provided? What will change on your 03?

Nothing - but when I drive/ride/fly my vehicle, I want to know EVERYTHING about it. I don't like surprises.

 

[hunterdan]

Using the old thread that was posted, I searched for the patent, since the patent number was listed and figured I would post the link.
http://patft.uspto.gov/netacgi/nph-...50&s1=5485894.PN.&OS=PN/5485894&RS=PN/5485894
This is for the Controltrak system, here is a short description.

[SIZE=+1]On demand vehicle drive system [/SIZE]

Abstract An on demand vehicle drive system monitors vehicle performance and operating conditions and controls torque delivery to the vehicle wheels. The system includes a plurality of speed and position sensors, a transfer case having primary and secondary output shafts driving primary and secondary axles and a microcontroller. The sensors include a vehicle speed sensor, a pair of primary and secondary drive shaft speed sensors, and brake and driveline status sensors. The transfer case includes a modulating electromagnetic clutch controlled by the microcontroller which is incrementally engaged to transfer torque from the primary output shaft to the secondary output shaft. When the speed of either the front or the rear drive shafts overruns, i.e., exceeds, the speed of the other drive shaft by a predetermined value related to the vehicle speed, indicating that wheel slip is present, clutch current is incrementally increased to increase clutch engagement and torque transfer to the secondary axle. When wheel slip is reduced below the predetermined value the current to the clutch is incrementally reduced. The method of operating such a system is also described.

I remember reading somewhere on this site saying that Borg-Warner recommended using one of their control modules to control the TC, but Ford decided to use their GEM.

After reading the other post more, I found more patent numbers that may be helpful. You can search them here at this site:
http//patft.uspto.gov/netahtml/PTO/srchnum.htm

Well, the further I look into this, the more complicated it gets. I've found more patents that may or may not cover the control trac system including patent no.'s:
5485894
5605201
5609219
5704444
3 of these are very similar, but one appears to be a system used in addition to the automatic system that overrides in extreme conditions.

Hopefully this helps.


Dan

 

[Donner]

for the record, I didn't throw out my manual

 

[Cozmik]

for the record, I didn't throw out my manual

I think the manual is a bit off. Don't know about you, but when my t-case engages I can feel the change in the front end. Now with the V8 if I punch it I get torque steer like a FWD when the auto 4x4 engages.