Four wheel drive

EFR2441 · Oct 2, 2005

I looked at a NH TC35A and TC35DA yesterday. Nice tractors. While looking under the machine, I noticed the front drive shaft was noticable smaller in diameter than the JD and Kubota. I asked the salesman about this, who told me it was not a true 4wd, but a front assist. He proceeded to tell me that the front wheels travel at a slightly faster rate than the rear wheels (when engaged) and the 4wd option is primarily for steering and not traction. This was the first time I had heard this, and am wondering if it is true.

Is this true of the NH tractors? If so, what about the other major brands. Any advice would be appreciated.

Thanks, Erik

thatguy · Oct 2, 2005

Hmmm... things that make you wonder.. Im curious what others have to say about it being 'assist' only, I have never heard of that in a tractor..

Keep us informed..

thanks
brian

MrSteve · Oct 3, 2005

Are you sure the shaft is smaller? The reason I ask is because on my MF-1533 you can't see the shaft. The shaft is in the pivot rod (not sure of the right name for it) for the front axle.

Here is what my MF- 1533 book says about the 4x4 part of the tractor...

"When front axle is engaged, ground speed of front tires will vary from ground speed of rear tires. This is to assist in steering when four-wheel drive is selected"

Now with that said above, I think your dealer has misunderstood what 4x4 is all about... IMO and I am sure in most others, 4x4 is for locking 2 axles together to help get traction NOT help in steering. YES it is true that the above statement says "assist in steering", but the main use for 4x4 is for traction. How many times as someone used 4x4 in a truck to HELP steer? Me, I've locked in for traction, not to help me steer (yes I live in Florida, BUT I am from Niagara Falls, NY).

LarryD · Oct 4, 2005

There have been several times I've forgotten to engage the "front assist' on my 33D while using ground engaging equipment, like a box blade.

Sure does "assist" a lot when going in a straight line. /forums/images/graemlins/shocked.gif Like no forward movement to forward movement.

BB_TX · Oct 4, 2005

Here are a couple sites describing the difference between 4 wheel drive and front wheel assist.
 first one 
 second one

MrSteve · Oct 4, 2005

Um Ok /forums/images/graemlins/blush.gif Soooo because my tires are SMALLER in front that means I have 4 wheel assist and not 4 wheel drive? Mud in my face... Then why would the Massy book say "Four-Wheel Drive" when it SHOULD say "Four-Wheel Assist"? That's it, I am taking this tractor back /forums/images/graemlins/crazy.gif .

RedRocker · Oct 4, 2005

I'm not buying it, if all four wheels are "driven", then it's 4 wheel drive, tire size may affect traction but is irrelevant as to whether or not it's 4 wheel drive or not. I've never heard of 4 wheel "assist". I know off roaders that run different size tires front and rear, they have different gear ratios at each end, just like tractors, it's still 4 wheel drive. IMHO /forums/images/graemlins/cool.gif

Farmwithjunk · Oct 4, 2005

I'm far from an authority on the subject, but I believe I have an idea on this topic.

I'm thinking the tractor industry uses the term "4WD" in cases such as big Ag tractors that run in 4WD on a continuous basis, and 4wheel assist is reserved for tractors that are in and out of 4WD as needed.

Some 4 wheel assist tractors dis-engage front drive when brakes are applied. When the front "assist" isn't needed, they function as any 2 wheel drive.

Bottom line is, they do the same thing.

Back a few years, when most front wheel drive systems were hydraulic driven, they were ALL referred to as "front assist". I think that when most manufacturers went to mechanical front wheel drive, they threw out the "assist" to get rid of the "stigma" that hydraulic drives had earned.

MrSteve · Oct 4, 2005

Ok I feel a bit better on the subject. I am sticking with a have 4x4 tractor and I will keep it /forums/images/graemlins/grin.gif .

bam747 · Oct 4, 2005

For what it's worth...

Go the John Deere or New Holland websites. Navigate your way to their Ag tractors page. Both include a "4WD" category. Go ahead and click on it. What do you see?

GIANT articulated steering "4WD" tractors with, typically, same size dual or even triple(!) R1 style tires on all four corners!

I've also noticed in my wanderings around the various tractor websites and locations like MachineFinder.com that the term "MFWD" (mechanical front wheel drive) is generally used to indicate four wheel drive systems used on standard non articulated tractors when the front tires are smaller in diameter than the rear tires.

BB_TX · Oct 4, 2005

I think it comes down to the fact that on true four wheel drive, the front drive components are built as strong as the rear drive components and designed to carry an equal load. On front wheel assist, they are not designed as heavy as the rear, and are there to carry only a fraction of what the rears are designed to carry.

Farmwithjunk · Oct 4, 2005

Call it 4WD, Call it Charlie, Call it whatever you like. If it does the job, and you're happy, just call it a good thing! /forums/images/graemlins/grin.gif

I'm not much on titles or names or symbols, or, well you get the idea. /forums/images/graemlins/wink.gif /forums/images/graemlins/smirk.gif

My dad always told me that 90% of his employees were happier with a title than they were with a raise. /forums/images/graemlins/crazy.gif

EFR2441 · Oct 4, 2005

Gentlemen: Thank you for all your help. What the dealer told me got me nervous. Mr. Steve, the front drive shaft on the NH was exposed, and was noticably smaller than competitors models. What you folks told me makes sense. I was worried that the NH models were not a true 4wd (or whatever they want to call it) as opposed to the JD, Kubota, or others. For obvious reasons, having power to the front wheels is very important to me and my purchasing decision. With this small issue resolved, I'm back to trying to decide which brand and model will be best for my needs (with the NH still in the running). Thanks again for everybody's help and input. Erik

ns_in_tex · Oct 4, 2005

Not sure about other models, but my Kubota L4610 drives all 4 wheels, but you can only lock 3 wheels up tight. Most of the time it doesn't make any difference, but once in a great while, I wish I could lock all 4 wheels.

There is no differential lock on the front axle. This means you can lose traction on one of the front wheels along with both of the rear wheels, under the right conditions. So you are sitting there spinning 3 wheels and wishing the one non spinning wheel had more pull.

Also I think this means you only have as much traction on the front as the wheel with the least traction.

RedRocker · Oct 4, 2005

Most all Jeeps, especially the older models are sold with open differentials. I've been stuck before with two wheels on the ground. Not anymore though, Detroit lockers took care of that little task. Seems like most tractors have a manual locking rear diff, and an open front, not too bad since steering can become a little tricky with a locked up front diff.

RedDog · Oct 4, 2005

Also I think this means you only have as much traction on the front as the wheel with the least traction. 

You said it Neal, and you are correct.

All tractors should be available with a front locker. At least that's my opinion. /forums/images/graemlins/grin.gif

LarryD · Oct 5, 2005

I had a friend (Navy transferred him) who love to rock crawl over in the Columbia River Basin. Seems to me he made a true 4wd using a welder. Of course he needed a trailer as well.

RalphVa · Oct 5, 2005

I think it's virtually impossible to match the wheel circumference travel distance of the front wheels with the rear wheels when they're different sizes. That's the main reason why most will tell you to take them out of 4wd when on hard pavement, to avoid undue front tire wear because the fronts are going a different circumferential distance from the rears.

On my JD, and I'll bet it's true on many of the smaller wheeled tractors, the recommended front tire size is not what came on the tractor. It's what they could probably find in the right quantity/price.

On my Gravely, the original tires were quite a bit larger in width and probably a little bit different in circumference from the replacement tires of the same size. They're different from manufacturer to manufacturer, apparently.

When my JD is in 2 wd, the front wheels will skid sideways some when turning. In 4wd, they don't. Makes a big different in slick or uneven terrain.

There are some Goldini orchard tractors made by JD in Italy that are same size front/rear and not articulated.

Ralph

Youare · Oct 5, 2005

I must admit that 4WD does assist in steering when making tight turns on soft ground. Many times with no weight in the loader bucket and some weight on the 3PH when turning on soft ground the front tires will try to go straight and plow a furrow as the tractor driven by the rear tires tries to go straight.

Once 4WD is engauged and the front wheels are driven they do assist in turning the tractor. They also assist the rear wheels in moving the tractor forward especially if there is any amount of weight in the FEL.

I know with my Kubota the front tires are going at a slightly faster pace than the rear tires when in 4WD.

Randy

MikePA · Oct 5, 2005

I think it's virtually impossible to match the wheel circumference travel distance of the front wheels with the rear wheels when they're different sizes 
I thought this was usually addressed by having a different gear ratio in the front differential?