Turn Front Wheels Out?

PAB_OH · May 5, 2006

I have a grey 'Bota, not sure if they will make a diff. or not but I thought I should state it.

Anyway, I live on a pretty good sized hill and the front lawn is pretty steep. I generally try to mow up and down but with the rice tires after it rains it doesn't do so well so I go across it. The pucker factor definitley goes up a notch but I haven't had reason to worry yet. I was looking at the front wheels tonight after mowing and noticed they look like they can be "turned out" to give me a wider stance. When I was looking to buy a tractor a few months ago I posted a picture of an Iseki TA that had the front wheels turned out and someone replied that the wheels should be "turned in" (narrow stance).

Am I missing something here? Wouldn't it make sense to make my front tires as wide as possible, like I have with the rears? Or are the front wheels not designed to take that kind of load?

PHOTO ATTACHED

Soundguy · May 6, 2006

Some manufacturers state that you can turn rims dished out to get a wider stance. CNH is like this. All the ford/NH units I've owened.. show dishing the rims for width.. however.. take cub cadet. A friend tells me his manual says that rims should not be dished out, that it places too much stress on front end components. ( guess they don't build them as strong as CNH units /forums/images/graemlins/shocked.gif /forums/images/graemlins/grin.gif ).

Also.. some rims are rigged with offset notches to prevent dishing.. etc..

check your manual..

Soundguy

Doc_Bob · May 6, 2006

I have looked at the NH/Case rear tires ( I am shopping) on the TC40 and TC 45). The sales folk and my eyes tell me that the rears can be spread wider, in fact, six differrent positions. One sales type told me that they do not (cannot?) widen the fronts.

Bob

RoyJackson · May 6, 2006

I swapped my front wheels side to side. This increased the track 3"-5". The increase is due to the way the wheels are dished. A side to side swap may work for you, if the inside dishing is deeper the the outer dish.

My Deere 790 manual recommends this in some circumstances. The tractor does feel more stable, but that is subjective.

The side to side swap is required because R-4 tires are directional (designed to give more traction in one direction). Those "rice tires" you mention are closer to Ag type tires, also directional (assuming you have 4WD). A side to side swap may work for you. Only down side is the valve stems would be on the inside as mounted. That's a bit more hassle to check air pressure.

Personally, I wouldn't operate a tractor on wet grass...either across the slope or up and down. Grass is pretty slick...too much potential for an accident (IMHO).

PAB_OH · May 6, 2006

( Also.. some rims are rigged with offset notches to prevent dishing

Soundguy )

Yep, I looked a bit coser and sure enough the surface that would mate with the axle has raised sections to prevent you from turning them around. I guess that answers that.

Thanks for the tip.

PAB_OH · May 6, 2006

( The side to side swap is required because R-4 tires are directional (designed to give more traction in one direction). Those "rice tires" you mention are closer to Ag type tires, also directional (assuming you have 4WD). A side to side swap may work for you. Only down side is the valve stems would be on the inside as mounted. That's a bit more hassle to check air pressure.

Personally, I wouldn't operate a tractor on wet grass...either across the slope or up and down. Grass is pretty slick...too much potential for an accident (IMHO). )

Yes I do have 4WD and I forgot that since they are directional a side-to-side swap would be needed. Regardless it doesn't look like I'll be able to swap them, see above post.

Also, I don't mow wet grass /forums/images/graemlins/crazy.gif, no way! I meant the ground gets soft and the rears dig in way too bad. Thanks for the reminder though.

N80 · May 8, 2006

The manual for my 4wd L4400 says not to do this with the fronts. It also says no liquid ballast for the fronts.

Av8r3400 · May 8, 2006

Step back and think about this for a minute.

The front axle pivots in the middle, no springs or anything, just a side to side pivot. If you widen the stance by reversing the wheels, will you add any stability?

No.

You will add more stress to the bearings in the front gear boxes and more stress to the steering linkages.

N80 · May 8, 2006

( Step back and think about this for a minute.

The front axle pivots in the middle, no springs or anything, just a side to side pivot. If you widen the stance by reversing the wheels, will you add any stability?)

I must not be stepping back far enough. It only pivots so far and it only pivots if it is on a different plane than the rear tires.......but no one has accused me of being the 'thinker' in the bunch.

PAB_OH · May 9, 2006

That argument could be had for widening the rear tires as well. ANYTIME you lengthen a moment arm you increase the moment (torque) applied to a system.

So my question wasn't without merit and I did step back to look at the problem before I asked it.

Using your line of thinking no one should put a FEL on their tractor either, because it puts more stress on the bearings and steering linkages as well (more load = more stress).

Now back to your original assertion, lets carry this to extremes. If I add 24" of length to my front axle per side (4 feet over all) have I added stability to my tractor? You bet I have. You try to tip over a tractor that has an additional 2 feet of axle sticking out to the side. I can assure you it will require a much larger input of force in addition to increasing the critical angle at which the tractor will tip (this is my definition of stability in this instance).

Regardless, it is not do-able on my tractor, I have a feeling though that it is possible and possibly even recommended for some tractors in some instances. That is why I asked.

JerryG · May 9, 2006

The front drive axle was originally an after thought. The front axle and its related bearings are much light duty than the rear axle. There are manufactures that will actually state in their manuals, not to reverse the front wheels and as you have found out, make the wheel to where you can't change them. Even if you could change them and there wasn't a problem with it, you would have to have the front axle several degrees out from the rear axle before it hit the axle stop. It wouldn't do any good until the stop was hit.

N80 · May 9, 2006

( Using your line of thinking no one should put a FEL on their tractor either, because it puts more stress on the bearings and steering linkages as well (more load = more stress). )

I'm just being picky and this is going off on a tangent, but that analogy only holds if the tractor was not made to accomodate a FEL. I suspect that the bearings and linkages for most current CUTs are designed specifically to handle the additional loads of a FEL. But possibly not the loads of a FEL plus expanding the effective front axle width. Just a guess.

RobJ · May 9, 2006

( That argument could be had for widening the rear tires as well. ANYTIME you lengthen a moment arm you increase the moment (torque) applied to a system.

So my question wasn't without merit and I did step back to look at the problem before I asked it.

Using your line of thinking no one should put a FEL on their tractor either, because it puts more stress on the bearings and steering linkages as well (more load = more stress).

Now back to your original assertion, lets carry this to extremes. If I add 24" of length to my front axle per side (4 feet over all) have I added stability to my tractor? You bet I have. You try to tip over a tractor that has an additional 2 feet of axle sticking out to the side. I can assure you it will require a much larger input of force in addition to increasing the critical angle at which the tractor will tip (this is my definition of stability in this instance).

Regardless, it is not do-able on my tractor, I have a feeling though that it is possible and possibly even recommended for some tractors in some instances. That is why I asked. )

Not really, the rear tires/axles are fixed, so if you try and push your tractor over by hand it's the rears holding it. The front axle pivots up and down, like suspension. The rears don't. Widening the fronts will give some stability, but not like widing the rears will. If the rear was set up like the front the tractor would tetor back and forth. Look at the old tricycle "cultivating" Deeres. 2 front tires close together. They were less stable than the wide gears for sure, but they didn't flip over when you ran over a brick.

Regarding the front tires and a FEL. The tires/wheels/bearings are set for a FEL and they usually have a zero offset (center of the wheel is in the center if the bearings). If you flip the rims and change the offset there will be extra leverage on the outside or inside bearing. Usally the outside if you are making the wheel sit further out. The problem is compounded because the outside bearing is usually the smaller of the 2, it handles less load as designed.

PAB_OH · May 9, 2006

RobJ, good analysis.
That puts it into perspective and maybe that is what the previous poster who disagreed with my logic meant as well, I just didn't pick up on it.

In the most simplistic model of a tipping event which ever axle is the widest (tires included) bears the brunt of the load in a "tipping" scenario. The only way to add stabilty with the front axle in a pure tipping event is to make it wider than the rears, probably not a good idea for many of the reasons listed above.

In a "turning-tipping" scenario I could see the benefit of a wider front axle though, look at 3 wheelers. But that is another argument completely.

Thanks for advice guys.

PAB_OH · May 9, 2006

N80, I agree with that statement as well. Being that my Kubota is fairly new (late 80's to early 90's) I would assume it might be engineered for a FEL, though I understand over in Japan they don't use them that much so maybe not.

It is a small one (Koyker 110) so hopefully it doesn't cause any undue stress to the front axle and it's components.

PAB_OH · May 9, 2006

Jerry,
I can appreciate that line of reasoning as well. Actually, that is what my primary concern was. Even if I did add stability to the axle would I be stressing the bearing by moving the load further out on the bearing.

I guess I should have been more clear. I did not know that the front axle and its components were more of an afterthought. I assumed if they designed a 4WD unit they would incorporate a more substantial load bearing system into the front axle to accomodate the increased loads present. If the front axle rotates at about 3-5% faster than the rear it will see more load from the "pulling" it does. Maybe the increas in strength of components isn't enough to really allow for a FEL though?

I got it so I'm keeping it though. I don't use it all day everyday so again, hopefully it doesn't wear the front components prematurely.

RobJ · May 9, 2006

The ATV is an interesting example which may apply somewhat to a tractor. But the ATVs problem was speed and direction of the weight transfer. I had an old 3-wheeler and on a hill at slow speeds it wasn't that bad. My Suzuky ALT-185 didn't have any suspension or springs fighting to keep the wheels on the gound...or the ATV upright. But when at speeds and turning the weight transfered to a spot where there was no support...the right or left front corner. Riding on 2 wheels was only fun if you meant to do it. /forums/images/graemlins/blush.gif You can still roll a 4-wheeler but it is harder. But again the 4-wheelers have springs trying to keep the wheels on the ground, tractors do not.

I have my wheels out as far as they go, somehow, somewhere when I was younger I got tip-o-phobia. It still freaks me out today to think my tractor is about to roll. And I've never rolled one either.

Av8r3400 · May 9, 2006

Okay. I'd love to take your bet. Easy money.

Take this to an extreme. Lengthen the axle to 10 feet wide. You will get the same result.

There is a pivot in the center of the axle. A fulcrum, like a teeter-totter. The width has done nothing for you.

If you widen the rear, you will get more stability because the axle is fixed. Not the front.

PAB_OH · May 9, 2006

Okay maybe me being a novice to tractors is catching up with me here.

Will the tractor pivot on the axle 360 degrees? I'll concede that the rears will see the entire load, until the side being pushed (or the high side, if on a hill) lifts off the ground. Then the tractor body will pivot on the front axle until....? Are there hard stops to prevent the body from rotating past a specific angle? If so, now the front axle will come into play.

I'm not saying you are wrong, I am asking. That is why I posted this question, I wasn't sure if I would gain anything by moving the front wheels out and if I did if that would create a situation that might be worse than just having to deal with a narrow stance on the front axle.

Based on what has been posted this far I have to believe it wouldn't be a good idea, nor would I gain any significant stabilty, by moving the fronts out even if I was able to, which I am not.

Now, if the pivot point on the front axle doesn't have hard stops built in to it then it is a non-issue anyway, you will most likley damage the tractor's frame or body once you get to a point where this information becomes critical. If a rear wheel lifts off the ground and the tractor starts to tip, if it reaches the point where there needs to be hard stops to prevent the body's pivot attach point from being stressed and there aren't any hard stops you got real problems I would imagine. IF you do have a load system in place to transfer that load to the front axle (i.e. hard stops) then the front axle and it's effective overall width becomes a critical data point.

Unfortunately for me, at that point (likely well before that point) I have lost all interest in what is now no longer an interesting scenario. I would be looking for some new undies, I'm sure.

So, you are right I think, turning the front wheels out doesn't do any good.
1. Because the tractor pivots on the front axle and by the time you reach the point where that axle becomes critical I have long left the tractor to fend for itself (I don't have a ROPS yet! /forums/images/graemlins/crazy.gif)
2. The front axle wouldn't be critical even if the body of the tractor were "fixed" much like the rear until it reached an effective length equal to or greater than the rear in a pure tipping scenario.

And just to be clear, I am saying you win. I am not challenging you to a bet or anything like that. You win, period. /forums/images/graemlins/grin.gif

KiotiJohn · May 9, 2006

I you notice where the FEL is actually mounted, you see that it is not sitting right over the front axle. The mounting brackets are back behind that and the arms extend out over the front wheels, quite a bit different that actually being mounted over them.

Both axles share in the load with this configuration.

John