MFWD

[shane]

As a generality, 4wd's operate in 4wd constantly. MFWD is a term generally accepted as applying to tractors that can be used in 2wd OR 4wd. There is no constant in the terminology throughout the tractor industry.[/QUOTE]

Now, while I know what you mean the problem is my truck (I know we're talking tractors) is 4WD and it is not in 4WD constantly. So, I would think that my truck (if talking tractors) should be a MFWD.

Sure is confusing Paw. Almost as bad as trying to understand women.

 

[prosperity]

Here is my understanding....

MFWD = Mechanical Front Wheel Drive.

In years past on some models, the front wheels were hydraulically driven using hydraulic motors. This of course had it limits due to hydraulic pressure and flow. The front wheels would stop pulling once the limits of the hydraulic system were reached.

Then enter "mechanical" front wheel drive where the front wheels are driven by a driveshaft and axles from the main transmission.

So, in my opinion anyway, MFWD is the same as 4WD.

 

[N80]

Like I've said, I just call mine what Kubota calls it: 4wd. JD sticks with the MFWD terminology described above. NH uses "FWD" for "Front Wheel Drive".

On our little tractors, you'll see most of the slippage while turning (changing direction) since one tire will be traveling less then the other (on the front).

Well, the front differentials on most of our tractors are completely open. Some may have diff locks, most don't. An open diff should allow for different wheel speeds during turning. And I've never heard of a limited slip diff on a tractor.....it would probably be an open diff plus bits and pieces within a few hours anyway!

 

[montejw]

As I've mentioned before, Kubota designates all of its tractors with a front drive train as 'four wheel drive' or 4WD. I also think that the fronts spin slightly 'faster' on my Kubota too...but I'm not sure.

They probably do. In researching tractor tires I found an explaination about the front tires sort of pulling the tractor along at a rate of about 1%-1 1/2% faster ground speed. Supposed to give better traction and better drivetrain wear.

 

[jovialjeeper]

In any FWD or MFD you want the front tires spinning faster than the rear. You need the fronts to pull you along. If they were turning slower than the rear, the rear would have to push the fronts ahead. On hard ground you would end up with the vehicle hopping because the fronts bind up and then spring forward. The tractor is geared for a particular rolling radius on the front and rears (whether they're the same size or different). Change the size and you need to re-gear,

Steve, at Case, the only thing we considered FWD was the Steiger. Its full-time. Anything else was a selectable MFD.

 

[Grrrr]

In any FWD or MFD you want the front tires spinning faster than the rear. You need the fronts to pull you along. If they were turning slower than the rear, the rear would have to push the fronts ahead. On hard ground you would end up with the vehicle hopping because the fronts bind up and then spring forward. The tractor is geared for a particular rolling radius on the front and rears (whether they're the same size or different). Change the size and you need to re-gear,

I think having the front wheels turning slightly faster than the back wheel causes positive traction and should give you better grip than having all the wheels going the same speed.

In the UK we only have two termiologies for tractors, 2wd and 4wd.

 

[Keith_B]

The fronts have to turn faster than the back. If the front and back made the same number of revolutions per minute the rear wheels being larger would cover more ground.

 

[RoyJackson]

The fronts have to turn faster than the back. If the front and back made the same number of revolutions per minute the rear wheels being larger would cover more ground.

Let's just say the fronts turn quicker to maintain the correct ratio with the rear tires. Ratio may not be the best term, but you get the point.
If the tires were the same fore and aft (as they are on the big, full time FWD machines), they'd be turning the same RPM.

The only time things get tricky is when one makes a turn while the front wheels are engaged.

 

[Grrrr]

I think there is also a point that when your travel on a hard road where the front wheels will not be able to slip slightly you should disengage 4WD to avoid transmission wind up.

 

[RoyJackson]

I think there is also a point that when your travel on a hard road where the front wheels will not be able to slip slightly you should disengage 4WD to avoid transmission wind up.

Yep...the only time one should use 4WD on hard pavement is if you're towing a load....and that's to provide more braking.