Difference Between 4WD and MFWD ?

[bigcut]

It's probably been asked before, but, what is the difference between 4WD and MFWD ? Is one better than the other or have advantages ? Is one typically more expensive ? How about maintenance & repair, problems, etc. ?

Appreciate any education you could provide me.
John

 

[k0ua]

I will take a crack at it and see what others say. 4WD, may or may not be "mechanical" as in MFWD (Mechanical Front Wheel Drive). Some front drive system are hydraulic with hydraulic motors on the front, not drive shafts, U joints, and differentials. Also some mechanical systems are not really designed to be full time 4wd system, but to only be used to assist the main rear drive, and are called MFWA as in "Mechanical Front Wheel Assist". Most CUT sized tractors are going to be Mechanical in nature, in other words, drive shafts, and such, not hydraulic, and are going to be considered "assist" not full time systems...One thing to note is the tires on most CUTS are much smaller on the front than the back, and do not have the pulling power that the rear tires do.

Others may argue some or all of these points, but that is what I think.

 

[hosspuller]

In the ag world, A 4WD is an articulated tractor... That is it steers by bending in the middle. A MFWD is a tractor that steers the front wheels while driving them.

 

[ModMech]

^^^ What he said, or "4 WD" can also refer to a "2 WD" tractor with 4 rear tires, but that's not common.

 

[MHarryE]

What Hossworld said - 4wd in ag refers to large articulated. MFWD is Mechanical Front Wheel Drive - like an old time 2 WD tractor with mechanical front wheel drive that can be engaged or not engaged. The 4wd tractors have the articulation joint in the exact center so there is no differential needed between front and rear. Consequently front and rear tires are the same size. MFWD is typically disengaged for highway travel. Our John Deere and New Holland tractors have an auto position on their MFWD. When the tractor reaches a certain ground speed the front wheels are automatically disengaged - assumption is the tractor is being roadbed. If the brakes are engaged the MFWD is automatically engaged to reduce stopping distance.

 

[bigcut]

What Hossworld said - 4wd in ag refers to large articulated. MFWD is Mechanical Front Wheel Drive - like an old time 2 WD tractor with mechanical front wheel drive that can be engaged or not engaged. The 4wd tractors have the articulation joint in the exact center so there is no differential needed between front and rear. Consequently front and rear tires are the same size. MFWD is typically disengaged for highway travel. Our John Deere and New Holland tractors have an auto position on their MFWD. When the tractor reaches a certain ground speed the front wheels are automatically disengaged - assumption is the tractor is being roadbed. If the brakes are engaged the MFWD is automatically engaged to reduce stopping distance.

Thank you for your response...however, I'm still unclear...must be me. I have an old Ford truck that I can lock out the front hubs and engage 4WD. I know some Ford's are equipped with hydraulics that enable one to shift on the fly from inside the cab. Is this anything like that ?

On tractors, is the MFWD more desirable or advantageous over what I'll call full-time 4WD ?

Sorry about my inability to grasp things. I appreciate your patience.
John

 

[Coyote machine]

You're confusing apples/oranges. Your furd truck has the ability to engage the front axle to make all 4 wheels pull when the front hubs are engaged, locked IN, not locked out. When unlocked the truck is rear wheel drive only. In the cab is a button that actuates 4wd electrically, instead of manual hub turning at the front wheels.
The posters were talking about articulating tractors which are pinned in the middle of the chassis/frame and allow all four wheels to turn, and the tractor front 1/2 can and does turn at the pivot point instead of the entire tractor following the front wheels in a straight line, therefore a more flexible turning radius, and all four wheels are independently turning and pulling at the same time. More traction, more maneuverability, etc. And they mentioned mechanical 4wd uses axles, differentials, etc. like your truck.

 

[Tx Jim]

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.

 

[ber72564]

It's probably been asked before, but, what is the difference between 4WD and MFWD ? Is one better than the other or have advantages ? Is one typically more expensive ? How about maintenance & repair, problems, etc. ?

Appreciate any education you could provide me.
John

bigcut, your profile says Garden Tractor. I too have a garden tractor. A John Deere X748 with HFWD (Hydrostatic Front Wheel Drive). There were previous models of the X700 series that had MFWD (Mechanical Front Wheel Drive). The difference is a MFWD has a mechanical drive shaft from the rear trans axle to the front axle. The front axle contains a traditional differential and transfer case all mechanically linked to the rear hydro static trans-axle where the power is generated.

A HFWD's front axle is actually two variable displacement hydrostatic motors where the fluid for the motors comes from the hydro static pump in the rear trans axle. There is no mechanical connection between the front and rear axles.

 

[bigcut]

Thanks ber,
I now understand what HFWD is....but must confess my understanding is still unclear on my original post. Thanks,
John

 

[ber72564]

Thank you for your response...however, I'm still unclear...must be me. I have an old Ford truck that I can lock out the front hubs and engage 4WD. I know some Ford's are equipped with hydraulics that enable one to shift on the fly from inside the cab. Is this anything like that ?

On tractors, is the MFWD more desirable or advantageous over what I'll call full-time 4WD ?

Sorry about my inability to grasp things. I appreciate your patience.
John

Differences not sure about Advantages. Some others might jump in here.

Both types allow the front wheels to rotate at different speeds during a turn. The HFWD allows the front wheels to rotate at different speeds than each other as well as different speeds than the rear wheels.

A MFWD transfers power to the front wheels via the mechanical link to the fixed displacement motor in the rear trans axle. Your max torque and max HP at the output of the fixed displacement motor in the rear will be shared across all wheels that are driving. The variable displacement pump tied to the fixed displacement motor gives you a constant torque across the entire variable HP range of the system at all driving wheels regardless of speed.

In a HFWD the max torque and max HP for the rear wheels is independent of the front wheels. You still have the same variable displacement pump feeding the fixed displacement motor for the rear wheels. Once again, this is a constant torque variable hp system. However, the rear variable displacement pump feeding the variable displacement motors in the front allow for both variable torque and constant HP based on the rotating speeds of the front wheels. Long speak for putting power where it is needed when it is needed even in a turn where the front wheel actually "pulls" the tractor through the turn. Reducing front wheel scuffing.

I also noted that when JD went to the HFWD, they also went to a slightly smaller yanmar diesel motor. The new motor generates the same power at higher RPMs. possible fuel savings, but not sure.

Hope this helps.

 

[ber72564]

Here is a good link basically describing what I said.

Hydrostatic transmissions | Hydraulics content from Hydraulics & Pneumatics

 

[ber72564]

Maintenance and repair - If you grind up a front axle MFWD might be less expensive to replace than a HFWD.
Life of machine, my bets are on the HFWD as longer lived, simply less mechanical metal on metal points.
Price - you will just have to comapre and see. JD no longer offers the MFWD in my model so I cant tell.
Performance wise the HFWD is smoother on the turn, the front wheels rotation is totally independent of the rear wheel speed. If the rears are slipping the fronts may not slip, and vice a versa.

 

[gudivada]

is MFWD is suitable for Agriculture

 

[Tx Jim]

gudivada
Yes MFWD is suitable for agriculture use.

 

[countrybumpkin]

As stated above in the AG world this is a 4WD

 

[countrybumpkin]

This is a MFWD or front wheel assist.

 

[PILOON]

Add to the discussion front wheel assist and all wheel drive.

IMHO if the front wheels are smaller than the rear then I call it front assist, with emphasis on ASSIST, ie some help.
Just look at the components, tires, differential shafts etc. Are they same as the rear? NO.
For that reason I only chain the rears on my tractor.

 

[woodchipper]

Add to the discussion front wheel assist and all wheel drive.

IMHO if the front wheels are smaller than the rear then I call it front assist, with emphasis on ASSIST, ie some help.
Just look at the components, tires, differential shafts etc. Are they same as the rear? NO.
For that reason I only chain the rears on my tractor.

Piloon:
I do not agree with your statement.
Front tire size has nothing to do with a tractor being a MFWD. Front tire size has more to do with load capacity, steering ability (the smaller the wheel, the better the turning radius), and traction. Your front differential dictates the tire size. It is a question of gear ratio. Ie: same tire size equals same gear ratio, so there is no binding in your axle, which would lead to rapid failure.
There is nothing wrong with using chains on all four wheels. The comon problem, wich leads to the so many front axel failures, is that the wear has to be equal on all four tires. If the fronts are worn down completely, the tire diameter is quite less than when it was brand new. Therfore, you are changing the front to rear ratio. So when puting chains on those front tires, you are agravating the situation way past the limit. Spin the wheels on hard surface, and you will get a broken axle in short order!:drool:
Stay warm!

 

[Gary Fowler]

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.