Four wheel drive

[BamaRob]

I think what he was saying was that you could never get the exact same circumference travel distance between the front/rear because of the different sized tires. Differing gear ratios can get it close, but it'd be tough to get them exactly in synch. They might be able to "tweak" it from the factory with factory installed tires, but then it gets hosed up when someone replaces the front tires with some that are slightly smaller/larger than the ones from the factory.

BR

 

[BB_TX]

Even natural wear and replacing only the fronts or only the rears with factory originals can have a fairly significant effect. A tire worn down by 1" off the diameter (1/2" worn off the tread) will change the circumference by ~3". If the fronts were replaced without replacing the rears, or vice versa, that would change the ratio quite a bit.

 

[Varmintmist]

</font><font color="blue" class="small">( 4wheel assist is reserved for tractors that are in and out of 4WD as needed. )</font>

It comes out ?????? /forums/images/graemlins/shocked.gif /forums/images/graemlins/shocked.gif /forums/images/graemlins/shocked.gif /forums/images/graemlins/shocked.gif /forums/images/graemlins/tongue.gif

 

[Boomerang1]

A tractor with 4wd is designed to have a lead or a lag depending on the need for each. A tractor with a lead will have the front wheels spin a little faster than the rear wheels. This will help with steering because the rear tires aren't pushing. You can change this either by changing gears or tires. Most mud boggers have the front wheels spinning faster than the rears so the front wheels pull you through the mud. When the rears spin faster, the rear end of the machine will try to pass the front. This is why the driveline gets bound up and makes going from 4wd to 2wd difficult.

 

[Farmwithjunk]

Gearing and tire size are used to get it "close", but by design, most MFWD systems employ SLIGHTLY faster (higher) wheel speed on the front ends to make them track better. It's only a marginal difference, but it's there.

 

[MikePA]

Boomerang1 and Farmwithjunk.....Thanks for the information. Really interesting. /forums/images/graemlins/cool.gif

 

[IH3444]

The NH company has the front spinning 2% faster than the rear. All the CUTs are FWD assist in my opion. If you go to the NH company site and click on the bi-directional tractor, that's true 4wd.

 

[jrepp]

This web page has some interesting info on 4WD.
http://www.knowledgebank.irri.org/ppfm/farmPower/WebHelp/FarmPower_lesson08.htm

 

[RedRocker]

Front assist is another way of saying four wheel drive. The definition of 4WD is power sent to all four wheels. It's real simple. /forums/images/graemlins/smile.gif

 

[getut]

I cringe everytime I hear that. Most of the time it is dealers who are laying the groundwork to weasel out of warranty repair job if it breaks... usually with statements like "you put too much stress on it and broke it, we can't warranty this".

If it's a tractor, it should be rugged and pull. I agree turning on pavement with a tractor in 4 wheel drive puts more wear on the system, but if that small amount of stress breaks it, then I wouldn't want that model tractor anyway. If it is a bad part and it breaks under that amount of stress, then that is one thing. But if a T-R-A-C-T-O-R will regularly break 4 wheel drive components if you use it as a 4 wheel drive.

I want a tractor where the sellers are confident enough to say... do your worst.. you won't break it unless you weaken it with a torch first.. .but just in case you do, we'll fix it.

I also get a chuckle when I hear dealers complain about broken front ends. Todays high tech designs are junk compared to old stuff. I remember my grandfather pulling on tree stumps and regularly lifting the front end 3ft off the ground and dropping it all at once when clutch gets pushed. Do that with any of todays tractors with their "high tech alloys" and they'll fall apart PLUS get you a voided warranty for being so bold as to suggest it should have held up.