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  1. #1

    Join Date
    Apr 2002
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    now in S.C.!!
    Tractor
    Yanmar FF205D

    Default definition of 4wd?

    Guys, I have a Yanmar (FF205) that has no 4wd shifter but is a 4wd tractor. My question is what constitutes 4wd? Up on the jacks I have one rear tire pulling and the opposite front tire pulling. this is a newer Yanmar ,1991. thanks, brett

    ps, the reason I'm asking is that I'm going to need turf tires soon and dont know about keeping the tire ratio if I am indeed in 4wd (or something like that) all the time.

  2. #2
    Platinum Member
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    Nov 2002
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    John Deere 4110 HST

    Default Re: definition of 4wd?

    I really don't know on a tractor, someone like EFC, or one of the other dealers would know. But I do know on a car or truck, 4 wheel drive just means one of the rear and one of the front is pulling at any one time. That is why they have all wheel drive out there now, then its all 4 wheels is pulling at one time. On two wheel drive they has pos-trac to have both wheels pull at the same time. other wise only one is pulling. So it comes out 2 wd is one pulling, and 4wd is 2 pulling.

  3. #3
    Elite Member
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    Red Bluff, CA
    Tractor
    Changes often!

    Default Re: definition of 4wd?

    I'm not familiar with an FF205 Yanmar, but if power goes to the front and rear axles you will need to keep the tire sizes correct.

    I'd like to see a picture of an FF205. Can you post one?

    Dave

  4. #4
    Gold Member
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    Jun 2000
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    Syracuse, New York
    Tractor
    1952 Case DC-4, 2001 JD4300 MFWD, HST

    Default Re: definition of 4wd?

    The only difference between "All wheel drive" and "Four wheel drive" as it pertains to automobiles, is that the 4wd vehicle will have a two speed transfer case where the AWD is only single speed. Without locking or limited slip differentials in the axles or some type of brake actuated traction control system the AWD vehicle won't get around any better than the 4wd one. The tractor must have some kind of full time 4wd setup if it does not have a lever to disconnect the front axle. In any case, it should be readily apparent by looking at the front axle of the tractor wether it is 4wd or not. If it is, you will want to properly match the tire diameters to maintain the correct lead ratio.

  5. #5
    Gold Member hosejockey2002's Avatar
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    Mar 2002
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    Auburn, WA
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    Kioti CK20 HST

    Default Re: definition of 4wd?

    <font color=blue>But I do know on a car or truck, 4 wheel drive just means one of the rear and one of the front is pulling at any one time. That is why they have all wheel drive out there now, then its all 4 wheels is pulling at one time.</font color=blue>

    On 4 wheel and all wheel drive vehicles, the wheels pull the same. The difference is a 4 wheel drive the driver can select between 2 and 4 wheel drive, and an all wheel drive vehicle is always "in" 4 wheel drive.

    What makes only one wheel on the front and rear spin is the "open" differentials in the axles. These allow one wheel to spin faster than the other when cornering. When the power applied to the axle overcomes available traction, generally the wheel with the least traction gets more power applied to it and it spins, which makes it look like your 4 wheel drive is only two wheel drive. A "limited slip" type differential does just that, it "limits" the amount of differential action, providing power to both wheels under most conditions. A locking differential like most tractors have on the rear mechanically locks the axle shafts together so both have equal power available to them. You wouldn't want to lock your differential on dry pavement and then try to make a tight turn. I'm sure there are others out there who are more mechanically articulate than I and can explain this better.

  6. #6
    Platinum Member
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    John Deere 4110 HST

    Default Re: definition of 4wd?

    I only said what Popular Mechanics said in an article a while back. I tend to believe it, for I know if you are on ice or snow, and you give a little too much gas, one tire and one tire only will spin till it bites in. And they said with awd they would both spin, not havn't one, I really wouldn't know. I have always got around just fine, in snow and ice, with just 2wd and that in the hills, so I'll most likely never find out.

  7. #7
    Platinum Member buppy69's Avatar
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    Western NC
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    Hinomoto E2804, Hinomoto N239,

    Default Re: definition of 4wd?

    Hosejockey is correct in his explanation. 4 wheel drive can be shifted in and out while all wheel drive is in gear all the time. Some early model Scouts had single speed transfer cases but were not all wheel drive.

    Eugene

  8. #8
    Platinum Member Trev's Avatar
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    May 2002
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    Williamson, NY (near Rochester)
    Tractor
    Currently tractor-less

    Default Re: definition of 4wd?

    Now if I understand this correctly, a genuine All-wheel-drive, like the Audi Quattro, will do just fine if even one wheel has traction. Any one. That's been my experience driving one. Perhaps I'm just saying what others have said in different words?

  9. #9

    Default Re: definition of 4wd? *DELETED*

    Post deleted by saw_dust

  10. #10

    Join Date
    Apr 2002
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    Yanmar FF205D

    Default Re: definition of 4wd?

    here you go, just dont drool.
    Attached Images Attached Images

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