Difference between 4WD and MFWD

[N80]

I think that almost all of these terms are proprietary terms; in other words, terms that certain manufacturers use for their own systems. Not all manufacturers use 'MFWD'. In fact, of the larger manufacturers, Deere seems to be the only one that uses it. Kubota uses the term 'four wheel drive'.

I think problems.....and arguments....occur when these terms are used genericly to describe the specifics of a front driveline. There is so much variation in the systems _and_ how they are supposed to be used, that generalized statements frequently will not apply.

[Dutch445]

To confuse things even more, Deere also used the term
"HFWD" which was Hydraulic Front Wheel Drive. So,
there have been 2 options for their "Two Wheel Drive"
tractors... the older HFWD, and today's MFWD.
Deere strictly refers to 4WD tractors as the articulating
high horsepower tractors.
I also think if you were to look at market share numbers,
and other industry information, they refer to these large
articulating tractors as 4wd, and everything else is
2wd, usually over 100hp or under 100 hp, etc.

[acs55812]

I thought MFWD was for Manual Four Wheel Drive meaning you had to manually pull a lever (or whatever) to put it in FWD and those labeled FWD meant all the time FWD.

As far a spinning faster if the front tires are smaller they have to spin faster to keep the ratio of front to back the same---don't just change tires without considering the ratio of the front to backs as this is compensated in the drive train and if wrong could ruin same.

[Dutch445]

MFWD = mechanical front wheel drive,
vs. the hydraulic drive on the older
20 and 40 series tractors..

[BTI]

Dutch445 Nailed it....
Or did he "spike" it......
LOL

BTI

[AndyMA]

Just to throw a little more fuel into the discussion... Remember in many cases the manufacturers called it Front Wheel Assist meaning it is not intended as true four wheel drive. Years ago, they almost all did this. Lately most literature has been calling it 4 wheel drive.

Andy

[N80]

You know there have been several heated conversations about 4wd systems lately. I think some of the confusion comes from the fact that '4wd' and 'MFWD' do not necessarily describe the same types of systems and we tend to generalize about systems that are very different.

For instance, my Kubota (and nearly all Kubotas as far as I know) have a bevel gear front drive system. There is no 'pumpkin' up front. Whereas the JD's I looked at yesterday all had a conventional looking front differentials and solid axles. I have a pretty good idea of how the JD's work since it is much like older 4wd trucks and Jeeps. Basically a front drive shaft connects to the front differential which transfers power to the axles. But I'm not real clear on how these bevel gear tractors work. I'm guessing there is a ring and pinion of sorts between the front axles and the front drive shaft, but it must be a very small set, maybe 1:1? And I don't see how this could have a differential effect, in other words, I'm guessing its solid. So were does the differential effect occur? Is there a center diff between the tranny and the front drive shaft (very unlikely)? Or does the differential effect come from within the bevel gear assembly?

And outside of these two types of systems (JD conventional type and Kubota bevel gear type) are there others that are significantly different from these two? (I'm just talking CUT and utility tractors here, by the way).

[machmeter62]

I have a Kubota L295DT I purchased nearly 30 years ago new, and has rarely been out of 4WD! The operators manual makes no issues about using it in 4WD. The parts manual shows a differential between the front and rear axle; therefore, where is the stress? Is it wearing out the differential? It still works as advertised! Weight wise, it has always had a loader and backhoe on it, and all four wheels filled with liquids. There is no whining in the drive train either? Maybe, it's a fuel mileage thing? It is called DUAL TRACTION and 4WD only, but I assume it falls under the manual type, since a lever is required to engage it? The total weight with the wheel fluids, backhoe, and loader, increased the basic tractor wt. from 2600# to 5000#+. If I had to stop and change the 4WD lever everytime I was on a hard surface, the lever would be worn out! I also checked with various Kubota rental yards over the years, and they said, "leave it in 4WD."

[HomeBrew2]

Originally Posted by N80

... So were does the differential effect occur? ...

At least on a BX, the differential effect comes from, ummm, the differential.
The bevel gears/final drive at each front wheel replaces the ring and pinion found in a "punkin". In other words, in a "punkin" there are 2 components, a final drive (ring and pinion) and a differential. No "punkin" on BX because the little bevel gears (spyder gears) that compose the diff fit in a tiny can. I think the original Hummer is another example of this configuration ... final drives at each wheel.

[N80]

Originally Posted by HomeBrew2

At least on a BX, the differential effect comes from, ummm, the differential.

Ah, one cannot argue with metaphysics.

The bevel gears/final drive at each front wheel replaces the ring and pinion found in a "punkin". In other words, in a "punkin" there are 2 components, a final drive (ring and pinion) and a differential. No "punkin" on BX because the little bevel gears (spyder gears) that compose the diff fit in a tiny can.

Bear with me, I'm kind of dense. You are saying that the final drive is in the bevel gear assembly beside each front wheel. I got that. But I'm still not clear where the diff is. (Please don't tell me its in the diff ). When you say the diff is in a tiny can, do you mean where the front drive shaft enters the axle shaft assembly? I can see that if there is no ring gear and the resulting ratio at the axle is about 1:1 (for each turn of the drive shaft there is one turn of the front axle) thus allowing for small gears and a small 'can'. If that's the way it goes then that makes sense.

I guess I was imagining a spooled front 'diff' with the possibility of differential action in the bevel gear assemblies allowing for the front wheels to rotate at different speeds. I don't even know if that is possibe. I was just trying to figure out why some folks describe 'binding' when they turn and I don't get any on my L4400. A differential effect at the bevel gear assembly would help explain that. However, a 1:1 ratio (thereabouts) at the diff would also help explain it.

I'm still not clear if my tractor has a center diff.