Mechanical Four Wheel Assist??

[K5lwq]

Yep. When I first started seeing them they were called Articulating. Then in my area it evolved to Center Pivot. Still called that now.

Center Pivot always referred to a type of irrigation system where I am from. Funny how terms differ in other locations.

 

[ovrszd]

Center Pivot always referred to a type of irrigation system where I am from. Funny how terms differ in other locations.

Yep, rotating irrigators are called center pivots here too.

 

[karatecop]

Your Rubicon has electric over air lockers in each axle. It also has a mechanical lever to select 2wd/4wd/4wd low.

Your tractor might have a limit slip front axle. That's not uncommon. Very rare to see a tractor with a selectable locker in the front axle. It definitely has a diff lock in the rear axle which is very common.

If you select 2wd and don't engage the diff lock you actually have 1wd. If you then engage the diff lock you actually have 2wd. If you select 4wd and don't engage the diff lock you actually have 2wd. If you engage the diff lock you actually have 3wd. Unless your tractor has a lockable front axle you never have 4wd.

Thanks, Richard.

Like I said, I knew I'd learn something along the way. Sometimes I wish my tractor had a locking diff for the front, but that's just machismo since I can't see where I would really need it -and it would probably get me into a lot of trouble. Especially considering the front wheels are considerably smaller than the rear ones and I'm not rock crawling with my tractor.

I think it's like when the martial arts started getting big in the US in the late '60s and early '70s - folks in the US just called any martial art "karate" not knowing (or caring to know) the difference between karate, quan'fa, taekwondo, judo, kung fu, etc. But I can't have a meaningful conversation with someone who is a martial artist without knowing the exact style they study. Knowing (and caring to know) the specifics and details places a conversation in context. Alas, I've made the same mistake with tractor drives. Thank you for clarifying - and for not beating me up.

I believe many folks get confused about drives in tractors because of the auto world "carry over" - they think the "F" in MFWD means Four instead of Front (and they don't know that M stands for Mechanical instead of Manual). I know that was part of my confusion. I also think that it's confusing because although I instinctively know that only one wheel gets power at any given time... I also know that each wheel still has the 'capability' of receiving power from the drivetrain. I understand how a differential works, allowing greater turning radius on the outer wheel than on the inner wheel.

I do thank you for the explanation. I do think that some other confusion may be because no one ever thinks of a 1WD anything. I instinctively know that a 2WD truck only has one wheel pulling at any given time - due to how a differential works - that the power is distributed to each depending upon the traction and the turn direction. But, I was thinking that since each has the 'capability' of pulling, it is a 2WD system... and thus... if all 4 wheels have the 'capability' of pulling, it's a four wheel drive system - not that they actually are pulling all at the same time, but they have the capability - and like I said, that's a carry-over from the automobile world.

So I think I've got it... let's see - in context:

2WD is really only 1WD at any given time depending upon traction and turn direction, unless you lock the rear diff and then you have true 2WD - both pulling at same time at same rate.

MFWD is Mechanical Front wheel drive and is only 2WD at any given time - with one front and one rear pulling - depending upon traction and turn direction, unless rear diff is engaged then you have 3 wheels pulling - the two rear at same rate and one in the front - depending upon traction and turn direction. Because it's mechanical, it is engaged on the downhill giving some more control of descent.

HFWD is hydraulic Front wheel drive (assist?) and only 2WD at any given time - with one rear pulling until front needs assistance - depending upon traction and turn radius. The front drive wheel might be directed (or chosen) by a check valve and driven hydraulically - the advantage being not tearing up turf during turns - but disadvantage being that it may not be engaged to control descent.

4WD is true - four wheel drive with all four wheels pulling at same rate at same time - normally on larger tractors - on tractors with same size wheels all round - and many times on articulating machines.

I'll have to check to see if I have limited slip diff on front - I'll lift the front with the FEL and turn one wheel by hand to see if the other spins the same direction or opposite direction (the later being open as opposed to limited slip diff).

Thanks again for your time. I knew I would learn a few things. Hopefully I've got it right now.

 

[LouNY]

I am going to disagree with much of what has been written regarding 1,2,3 or 4wd.
The original nomenclature of 4x2, 4x4, 6x2, 6x4, 6x6 was referring to the number of powered axles compared to the total number of axles on a piece of equipment.
To keep it simple for a minute a so called 2wd truck has 4 axles with 2 of them powered, so a 4x2.
When that 4 axle vehicle has power to all 4 axles it is a 4x4. When you add more axles you get your 2wd truck with 3 pairs of axles so a 6x2, power another axle set and it's a 4x6, power the last set and you end up with a 6x6.

A differential on an open rear end does not give you one wheel drive, both axles or wheels will receive the same amount of torque or twisting power it doesn't matter if you are driving straight or driving in circles both axles will receive the same amount of torque what your tires do with that torque is another matter, if one tire is in a low traction situation and the other on a high traction surface if 50 pounds of torque will pin the low traction tire it will spin but your other tire will still have that same 50 pounds of torque applied to try and move the equipment, it it will move with 50 it will move if it needs 75 pounds it won't. All standard open differentials will work that way from lawn mowers to large tractors to big trucks including the inter axle different on 6x4's and 6x6's.

Limited slip differentials either through clutch discs or gear effects will try to reduce the differential action and increase the torque applied to the tires but both tires will still be receiving the same amount of torque.
A Detroit locker type of differential transmits the same amount of torque to each axle but allows one axle to turn faster then the most heavily loaded.
A differential lock simply removes the differential action and delivers the identical amount of torque to each side.

 

[ovrszd]

I am going to disagree with much of what has been written regarding 1,2,3 or 4wd.
The original nomenclature of 4x2, 4x4, 6x2, 6x4, 6x6 was referring to the number of powered axles compared to the total number of axles on a piece of equipment.
To keep it simple for a minute a so called 2wd truck has 4 axles with 2 of them powered, so a 4x2.
When that 4 axle vehicle has power to all 4 axles it is a 4x4. When you add more axles you get your 2wd truck with 3 pairs of axles so a 6x2, power another axle set and it's a 4x6, power the last set and you end up with a 6x6.

A differential on an open rear end does not give you one wheel drive, both axles or wheels will receive the same amount of torque or twisting power it doesn't matter if you are driving straight or driving in circles both axles will receive the same amount of torque what your tires do with that torque is another matter, if one tire is in a low traction situation and the other on a high traction surface if 50 pounds of torque will pin the low traction tire it will spin but your other tire will still have that same 50 pounds of torque applied to try and move the equipment, it it will move with 50 it will move if it needs 75 pounds it won't. All standard open differentials will work that way from lawn mowers to large tractors to big trucks including the inter axle different on 6x4's and 6x6's.

Limited slip differentials either through clutch discs or gear effects will try to reduce the differential action and increase the torque applied to the tires but both tires will still be receiving the same amount of torque.
A Detroit locker type of differential transmits the same amount of torque to each axle but allows one axle to turn faster then the most heavily loaded.
A differential lock simply removes the differential action and delivers the identical amount of torque to each side.

Absolutely correct!!!