Difference Between 4WD and MFWD ?

[art]

Four wheel drive covers a lot of variation for many people but there are differences to what we are using the different types for.

With the nearly true four wheel drive both axles have the same size tires as well as the same brand so that both axles spin at the same speed. You might have noticed the word true four wheel drive, I threw that is as if the tractor doesn't have a locking system for the axle you still only have two wheel drive(one tire on each axle) to spin. Many of these tractors carry loads up to 50% and more load on the front statically, once the towed piece is engaged it is reduced.
MFWD has smaller fronts then rear and unlike two wheel tractor loads of 25% on the front they are normally 35% of the tractor weight without loaders. These are not meant to be ballasted to 50% front do to the lighter front ends, not only from the drive components that we know are often out of a fifty horsepower tractor being used on the front of a 150 horsepower tractor but also the structure to support it! Many of these front ends do use a differential lock of some sort so you can get four wheel drive with the differential lock or a minimum of three wheel drive. Most MFWD's have a lead built into the front axle to assist in turning as well as pulling. This does cause front tire wear to be faster especially if the lead is in excess of 4 to 5% but they do wear faster by nature as they are turning faster then the rear tires.
Weight distribution is a important part of making a tractor pull equipment. To have to much weight located in the front reduces the ability to transfer to the rear which is designed to carry the bulk of the load. To just add weight to a piece might make it worse then what it might be if lighter but with better weight distribution.

 

[arlen4720]

I don't agree that on the MFWD tractors that the front wheels are just assisting. Recently I broke the front drive shaft on my tractor (related in another post) and it didn't have enough traction to climb the ramps on my trailer with just the rear wheels pulling. I had to locate my trailer next to a slope so the ramps would be level in order to load it on the trailer. My front tires are wearing much faster than the rear due to them doing most of the pulling (IMO). With FEL on a CUT or Utility tractor, about 70% of the weight is on the front wheels so they are going to have more traction than the rear. Without an FEL, it might be more equal but still more weight on the front since that is where the heavy motor is.

If you have 70% of the weight on the front, then I would say that you are not ballasted correctly. My JD 4720 manual suggest that you ballast the machine where 65% of the weight is on the rears. The axle capacities listed in the manual are Front Axle 3528 lb, and Rear Axle 5292 lb, so the 65%/35% ratio bears out there too.
The rear tires are larger, wider, and have deeper lugs than the front. The fronts also spin probably 3 or 4 times faster than the rears.
I think that if you ballasted your machine correctly, you wouldn't be experiencing these problems.

 

[paulfun9]

I think too much is lost in translation. Its like having a power shuttle or A hydro shuttle pretty much the same thing right?

Four wheel drive is four wheel drive no matter how you slice it! Unless you have a method that will only let the front wheels assist if the rears start to loose traction its still four wheel drive no matter what the company wants to call it in their effort to be different or stand out. Tire size has absolutely nothing to do with it.

If I change the gear ratio in my truck to be able to run bigger tires on the rear than on the front is it then no longer four wheel drive? No its still 4 wheel drive with different size tires front to rear!

 

[bcp]

Having worked on large farms through the period when the large 4WD articulated tractors were introduced, (Versatiles, mid-60's) I have an opinion on the reason for the different names. But it may be different in other parts of the country.

At that time, about the only 4WD tractors were the large articulated ones. If anyone mentioned "4WD tractor," you knew it was a large articulated one they meant.

I believe that "MFWD" and "front wheel assist" was a designation to identify and differentiate the later conventional-style tractors with 4WD from the large, articulated 4WD tractors that were common before them.

Bruce

 

[Tx Jim]

If you have 70% of the weight on the front, then I would say that you are not ballasted correctly. My JD 4720 manual suggest that you ballast the machine where 65% of the weight is on the rears. The axle capacities listed in the manual are Front Axle 3528 lb, and Rear Axle 5292 lb, so the 65%/35% ratio bears out there too.
The rear tires are larger, wider, and have deeper lugs than the front. The fronts also spin probably 3 or 4 times faster than the rears.
I think that if you ballasted your machine correctly, you wouldn't be experiencing these problems.

Amen buddy, I agree that if 70% of the weight is on the frt axle THEN rear counter ballast is desperately needed and I also think frt axle of said machine is headed for a catastrophic failure.

 

[rmk700]

Pretty much already explained but here is a link that explains the difference well.

What Is an MFWD Drive? | eHow

 

[5083Guy]

Back in the heyday of large 4WD tractors besides articulated models that pivoted in the center some manufacturers built "crab steering" where both frt & rear wheels steered similar to MFWD frt axle.

Neighbors run this Beast.

 

[rmk700]

E

Having worked on large farms through the period when the large 4WD articulated tractors were introduced, (Versatiles, mid-60's) I have an opinion on the reason for the different names. But it may be different in other parts of the country.

At that time, about the only 4WD tractors were the large articulated ones. If anyone mentioned "4WD tractor," you knew it was a large articulated one they meant.

I believe that "MFWD" and "front wheel assist" was a designation to identify and differentiate the later conventional-style tractors with 4WD from the large, articulated 4WD tractors that were common before
them.

Bruce

I'd say your very likely correct on your opinion of how the term MFWD came about.

 

[MHarryE]

John Deere introduced the PFWA (power front wheel assist) on the 4020 and 5020 in 1966. It was a hydrostatic front wheel drive they advertised as being able to supply 20% more traction than the base 2 wheel drive models. They were a major improvement in performance but reliability left much to be desired. Since the idea worked well it evolved into the MFWD (mechanical front wheel drive). Note that the new terminology changed assist to drive partly to differentiate the improved capability of the mechanical front wheel systems. So today's system is not true 4WD like an articulated version (which are seldom 4WD anymore - mostly 8 or 12 wheel drive). Still on the MFWD tractors you mow see a lot with duals or triples all the way around on the high horsepower models. Like the farmer who was a bit upset with the police in a New England state a few years back. His tripled Case Magnum helped him roll right over and crush something like 8 city vehicles.

 

[MORRISONSTEEL]

dealers reference to 4wd, 2wd, mfwd, assist etc comes primarily from market share terms used to seperate those tractors. In the Marketshare world any tractor that is not an articulated machine as mentioned in previous posts is considered a 4wd tractor. All others are simply referred to as 2wd drive tractors regardless of power going to the front wheels. Just trying to give some insight to dealership lingo.