Difference between 4WD and MFWD tractors, updated

[mred2]

cow may not be a bull. old hands make mistakes.

 

[Jstpssng]

In cars and trucks, 4wd is part time, awd is all the time. Either can have locking mechanisim of some sort on one or more diffs, or none at all. Some modern 4wd trucks have automatic mode, which makes it not that different from some forms of awd.

Another older definition is that 4wd does not have a center diff, awd does. That was true until some car awd systems come out with viscous couplers or computer controlled clutches instead of center diffs.

(the awd's center diff is needed because in a turn the front wheels take a longer path than the rears. That's why a typical 4wd system slightly overdrives the front wheels vs the rear and why they should not be operated on high traction surfaces).

If you see an old International Scout with "four wheel drive" on the cowl it meant that it had what we now know as 4 wheel drive; one powered wheel on each axle. If it said "all wheel drive" the differentials would lock and you had all 4 tires pulling.

 

[Farmer495]

The line only got blurred when the townies moved to the country and started buying little tractors, so the "new" dealers took on their lingo, to sell more tractors to them... lol

Back when farmers, WERE farmers, this question never came up, EVERYONE knew what a 4wd was and what a MFWD was... Even what "front wheel assist" was/is...

There you have it, so bash me for saying the truth...

SR

When would you say this occurred? My local dealers of all brands always called a 2wd tractor a 2wd and the same tractor with "front wheel assist" a four wheel drive. I think the line got blurred many, many years ago, and it wasn't the dealers catering to the city folk. See a page from my 1984 International Operators manual for 84 series utilities, a farm tractor that isn't a "four wheel drive".

 

[ovrszd]

In 1968 I went to the Iowa Farm Show. I believe it was near Grinnel but not sure. I saw two tractors I'd never saw before.

The first was a John Deere center pivot. Can't remember the model. It was called a 4wd tractor.

The second was an Oliver. Maybe a 2150? It was equipped with FWA. And that's what it was called.

There was no confusion then. Everyone interested in tractors knew the difference.

Obviously in the next 15 years the waters began to muddy. 4wd sounds more manly and tough. FWA sounds weak and inadequate.

That wasn't felt by owners that worked them every day. It was felt by the potential buyers that Rob referred to earlier.

 

[LouNY]

Ah, but back when the Oliver 50 series where new it could have been a hydraulic front wheel assist,
Dumont Museum Photo Album

or a mechanical front wheel assist;
Dumont Museum Photo Album

and where does this fit in, no way to disengage the front drive here, and it's front steer with equal size tires all around;
Pair of Unique Ford County Tractors in Minnesota | Machinery Pete

 

[Sawyer Rob]

When would you say this occurred? My local dealers of all brands always called a 2wd tractor a 2wd and the same tractor with "front wheel assist" a four wheel drive. I think the line got blurred many, many years ago, and it wasn't the dealers catering to the city folk. See a page from my 1984 International Operators manual for 84 series utilities, a farm tractor that isn't a "four wheel drive".
View attachment 596018

BUT, that's in Canada, where they can be standing right next to a generator, and call it "hydro"!! lol

SR

 

[PILOON]

OK. now to muddy the waters.
"Front wheel assist".

 

[Farmer495]

BUT, that's in Canada, where they can be standing right next to a generator, and call it "hydro"!! lol

SR

Haha, must be regional, we don't call it hydro in these parts eh? More like "power goes out and I start up the generator"

Check out the back page of the 84 series operator manual. IH US book and printed in USA so technically my Canadian dealer would be right calling it a four wheel drive when selling these in the 80s. Weird since we bought an England built IH in Canada that came with a USA operators manual.

 

[oosik]

My new Ram Power Wagon has 2WD, 4WD & AWD. I can throw the lever into 4WD and it puts power to both the front & rear drive lines. I can twist the knob and LOCK the front, rear & middle differentials. At that point, I better be in something pretty slick. Power is going, 25%, to each of the four wheels. No slipping in the mid differential nor the front or rear differentials. This last case is what I would call TRUE, 4WD.

 

[Oldpath05]

Ah, but back when the Oliver 50 series where new it could have been a hydraulic front wheel assist,
Dumont Museum Photo Album

or a mechanical front wheel assist;
Dumont Museum Photo Album

and where does this fit in, no way to disengage the front drive here, and it's front steer with equal size tires all around;
Pair of Unique Ford County Tractors in Minnesota | Machinery Pete

I figured it out.................

hydraulic front wheel assist= Hydraulic Four Wheel Drive>> HFWD

mechanical front wheel assist= Mechanical Four Wheel Drive>> MFWD

no way to disengage the front drive = Fulltime Four Wheel Drive>>> FFWD

four wheel drive tractor= FWD = All the above.........

Rubber band front wheel assist tractor = RBFWA <<< Sold by Fred Flintstone and sons...........

 

[3Lfarms]

Ah, but back when the Oliver 50 series where new it could have been a hydraulic front wheel assist,
Dumont Museum Photo Album

or a mechanical front wheel assist;
Dumont Museum Photo Album

and where does this fit in, no way to disengage the front drive here, and it's front steer with equal size tires all around;
Pair of Unique Ford County Tractors in Minnesota | Machinery Pete

I like that Ford!
County was a good name for it. That was probably the turning radius.

 

[RickB]

I like that Ford!
County was a good name for it. That was probably the turning radius.

Just about.

 

[SPYDERLK]

Booooooooooooooooooooooooooooooooo, Baaaaaaaaaaasssssssssssssssssssssh, I dont like that answer..................

My tractor is not a Mechanical Front Wheel Drive tractor. It's a Mechanical Four Wheel Drive tractor, with one wheel on front that has Optional Drive Capability ODC, meaning when the tractor gets stuck one wheel just sits there to help hold up the front end................

No. Both wheels apply the same drive force in a std differential. With a limited slip diff both wheels will spin if both have traction beyond some minimal value. The latter arrangement can garner full tractive force from both wheels.

 

[Jstpssng]

My new Ram Power Wagon has 2WD, 4WD & AWD. I can throw the lever into 4WD and it puts power to both the front & rear drive lines. I can twist the knob and LOCK the front, rear & middle differentials. At that point, I better be in something pretty slick. Power is going, 25%, to each of the four wheels. No slipping in the mid differential nor the front or rear differentials. This last case is what I would call TRUE, 4WD.

NOW we're getting into meaningful discussion. :thumbsup: That must be why it's called a PowerWagon! Years ago a friend bought a GMC which would also lock up both axles. He said "I don't know what it will take to stop it, but it will be something mighty big."

 

[jeffgreef]

I thought MFWD meant Manufacturers Four Wheel Drive to distinguish it from aftermarket front drive axles which were available in the 60s and 70s. But I guess not.

 

[Oldpath05]

No. Both wheels apply the same drive force in a std differential. With a limited slip diff both wheels will spin if both have traction beyond some minimal value. The latter arrangement can garner full tractive force from both wheels.

Are you saying my tractor has a limited slip front end? Almost seems like we're creating more questions then answers, sign of a normal thread.

 

[ovrszd]

Yeah, this thread is wandering into fantasy land.

 

[Sawyer Rob]

My MFWD tractor has "mechanical" diff locks on BOTH, front and rear axles.

SR

 

[SPYDERLK]

No. Both wheels apply the same drive force in a std differential. With a limited slip diff both wheels will spin if both have traction beyond some minimal value. The latter arrangement can garner full tractive force from both wheels.

Are you saying my tractor has a limited slip front end? Almost seems like we're creating more questions then answers, sign of a normal thread.

It might be limited slip or open. It should be in your tractor specs. Its almost surely not a posi-locker cuz that would really hamper turning.

The worst case for motive force would be the open diff because its limit is 2x the force delivered by the wheel with least traction. If one wheels on ice its almost like both are.

A limited slip is better, sending more torque to the wheel with more traction.

A locker is like a solid axle. It forces both wheels to turn equally.​

How Differentials Work | HowStuffWorks

My 7520 front is a Carraro limited slip. If one wheel has no traction it just spins like its an open diff. ... But if one has ~ 20 or 30% of what the other has they both will spin.

 

[SPYDERLK]

My MFWD tractor has "mechanical" diff locks on BOTH, front and rear axles.

SR

I sure wish I had that sometimes. A Kioti I saw once had it. Im sure it comes in handy.