Regarding 4x4...

[Gary Fowler]

I've been told that AWD is completely different than 4WD.

My Olds Bravada is AWD but only kicks into 4WD when it senses the rear tires slipping. It was a real PIA when going up an icy hill side road. It would kick into 4 WD then back to 2WD then back again to 4 WD. It sure made steering a bear to control. I wish it had some way to lock it in 4 WD when needed. Also I think the AWD cars are designed for only one wheel on each axle to be powered and that is in a cross as in left rear and right front.

 

[bigtiller]

Large ag. tractors like this bad boy are 4WD all of the time.

View attachment 515697

Steve

That is a 4WD tractor.

Using the term 4WD with our tractors is a common mistake. But we have been doing it for so long that is has become the norm and some even think it is now factual. If your lawnmower or tractor is articulated and all 4 wheels are powered, it probably is 4WD. Everything else is Four-Wheel-Assist (FWA).

 

[smstonypoint]

That is a 4WD tractor.

Using the term 4WD with our tractors is a common mistake. But we have been doing it for so long that is has become the norm and some even think it is now factual. If your lawnmower or tractor is articulated and all 4 wheels are powered, it probably is 4WD. Everything else is Four-Wheel-Assist (FWA).

Just curious. I understand all true 4WD tractors have the same size wheels front and back, but are they all articulated?

Steve

 

[daugen]

Gary, replace the clutch packs in your Bravada yet? Mine was built wrong, had assembly tarry goop clogging up half of suction line for front wheel differential, clutch packs burned out, until they finally took the whole thing apart and found the bad pickup. Nice looking SUV too...I never had that on-off problem you have though.

aren't tractors their own special acronym, MFWD, multi function wheel drive? probably have this screwed up, but that was always the JD designator.
I think for most of us we would consider 4wd something you shift into, and awd as something you leave on. Sure have been a lot of variations on that, starting from manual front hubs.

Does a 4wd tractor power three wheels until the rear diff lock is activated, then four?

 

[bigtiller]

Just curious. I understand all true 4WD tractors have the same size wheels front and back, but are they all articulated?

Steve

In a word, yes.
Also, MFWA (Mechanical-Front-Wheel-Assist) is a Deere term to define the difference from a short lived hydraulic drive option. The hydraulic part went away but they kept the "M" part of MFWA. Sometimes people get things mixed up and MFWA becomes MFWD, which has different meanings to different people.

 

[TerryR]

Hmmmm - wondering. For those of you that leave your tractor in 4WD "most of the time". Do you leave your pickup in 4WD "most of the time" also? And if not, then why not?

No, because it is on pavement most of the time. But I do put it 4WD every time I drive up my driveway because if I don't it throws the gravel a lot worse.

 

[teg]

...Does a 4wd tractor power three wheels until the rear diff lock is activated, then four?

I think most are just 2 wheel drive when 4x4 is in gear (one front and one rear tire is powered). Can't tell you how many times I get high centered rear left and front right just spinning in the air!

I also (think) the front is only one wheel drive... even if you lock the rear differential. Anyone knows for sure?? So why have we not been calling these 3wd?!?!

 

[Creamer]

Large ag. tractors like this bad boy are 4WD all of the time.

View attachment 515697

Steve

There are a lot of differences between this and an FWA. #1 is weight distribution there is very little weight on the rear until it starts getting drag on the drawbar which is not when it is going down the road. #2 articulated steering which means the rear tires follow the same path as the fronts, i.e. the wheels have to go around the same number of times vs a front wheel steer where the rear takes a shorter path around a corner. #3 the entire driveline is built much heavier to take the slight variation between the axles. #4 Ag tires - the lugs flex a lot more than R4s or others.

To answer another question there were some early 4WDs that were not articulated - IH 4166, Case 70 series and a few others - but they all had drivetrain issues. Steiger and Versatile were articulated and the others soon copied.

 

[Creamer]

I've been told that AWD is completely different than 4WD.

AWD drives have a limited slip differential between the front and rear to remove the driveline bind.

 

[Creamer]

I'm not driving off road all the time... and yes, I've driven to my friends house more than a few times in 4x4 with my truck, too.

Also, you have heard of All Wheel drive, they are in 4x4 all the time...

Did that by accident one time and it cost me a front hub in my 92 Ford F150.