Tires L5030, increase stability by widening front end tires??? Not sure, difficulties found

[SPYDERLK]

Words like surely are easy to say but I prefer to do the math. Lets look at a static diagram of a tractor front end with the tire set six feet wide . Lets set the load of the front of the tractor on the king pin at 3000 lbs including the weight of the axle and what share comes to the front axle from the load in the bucket. Then add in 300 lbs for each tire and rim centered three feet from the king pin. Now consider if we hold the right tire ridgely and remove the support from under the left tire what are the rotational forces placed on the flange of the right tire. I get 3000 *3 ft plus 300*6 feet for a total of 10,800 ft lbs of torque. Now set out the tires to a full eight feet. I get 3000 *3 feet (the flange to king pin distance didn't change) plus 300* 7 feet ( rt. flange to center left tire load) for a total of 11,100 ft lbs or a 3% increase.
I see nothing surly about a 3% increase causing a failure. Do you?

Why doesnt the flange to kingpin distance increase by a foot?
larry

 

[TripleR]

Page 68 of my manual says don't do it for what that's worth. Stress factors and all that other stuff just goes over my head.

 

[vtsnowedin]

Why doesnt the flange to kingpin distance increase by a foot?
larry

Because the axle length to the flange didn't grow and your calculating the stress at that point. The weight of the right tire would have a moment arm equal to the distance from the center of the axle to the bolt circle or about four inches and be a force reacting opposite to the load on the other end. This load would be shared by the top half of the hub bolts and be balanced by the bolt tension you apply when you tighten the lug nuts. Bolt tension varies with shaft size of the studs and the torque applied but can be in the 30,000 pound range per bolt. in my wide example above 11100 lbs/ .33 feet (4") divided by 3 bolts above the center-line of the hub gives a bolt stress of 11,212 per bolt or about one third of their working strength.

 

[repete]

I will never again reverse my front wheels. After replacing two axle housings and multiple bearings I finally looked at what I was doing wrong.

I looked at the wheels in relation to the drop portion of the axle. When the wheels are in the "narrow" position the center of the wheel aligns with the center of the support structure. When reversed "wide" position, the wheel center puts a greater load on the outer portion than the inner portion. This caused bearing failures repeatedly. I also cracked the drop portion of the housing, presumably from the unequal loading.

In the end, it cost me $1,500 - $2,000 to learn the lesson of why the factory geometry was correct. I set the wheels back to the "narrow" position and have not had a problem since. I now have right around 5000 or so hours on a little L2550, that has been worked VERY hard.

 

[vtsnowedin]

I will never again reverse my front wheels. After replacing two axle housings and multiple bearings I finally looked at what I was doing wrong.

I looked at the wheels in relation to the drop portion of the axle. When the wheels are in the "narrow" position the center of the wheel aligns with the center of the support structure. When reversed "wide" position, the wheel center puts a greater load on the outer portion than the inner portion. This caused bearing failures repeatedly. I also cracked the drop portion of the housing, presumably from the unequal loading.

In the end, it cost me $1,500 - $2,000 to learn the lesson of why the factory geometry was correct. I set the wheels back to the "narrow" position and have not had a problem since. I now have right around 5000 or so hours on a little L2550, that has been worked VERY hard.

Considering that the tractor data for that tractor only list one front axle width for 4WD and the number of threads on TBN about front axle problems in that size class Kubota I agree with you. If you need more then 44.1 inch front spread for stability get a different tractor.

 

[SPYDERLK]

Words like surely are easy to say but I prefer to do the math. Lets look at a static diagram of a tractor front end with the tire set six feet wide . Lets set the load of the front of the tractor on the king pin at 3000 lbs including the weight of the axle and what share comes to the front axle from the load in the bucket. Then add in 300 lbs for each tire and rim centered three feet from the king pin. Now consider if we hold the right tire ridgely and remove the support from under the left tire what are the rotational forces placed on the flange of the right tire. I get 3000 *3 ft plus 300*6 feet for a total of 10,800 ft lbs of torque. Now set out the tires to a full eight feet. I get 3000 *3 feet (the flange to king pin distance didn't change) plus 300* 7 feet ( rt. flange to center left tire load) for a total of 11,100 ft lbs or a 3% increase.
I see nothing surly about a 3% increase causing a failure. Do you?

Why doesnt the flange to kingpin distance increase by a foot?
larry

Because the axle length to the flange didn't grow and your calculating the stress at that point. The weight of the right tire would have a moment arm equal to the distance from the center of the axle to the bolt circle or about four inches and be a force reacting opposite to the load on the other end. This load would be shared by the top half of the hub bolts and be balanced by the bolt tension you apply when you tighten the lug nuts. Bolt tension varies with shaft size of the studs and the torque applied but can be in the 30,000 pound range per bolt. in my wide example above 11100 lbs/ .33 feet (4") divided by 3 bolts above the center-line of the hub gives a bolt stress of 11,212 per bolt or about one third of their working strength.

Id say youre wrong. The wheel is moving outward a foot. Any linear force on that wheel has an extra foot of leverage on the axle, bearings, lug nuts, axle housing etc. But maybe iv totally missed what youre saying. :confused2:
larry

 

[vtsnowedin]

Id say youre wrong. The wheel is moving outward a foot. Any linear force on that wheel has an extra foot of leverage on the axle, bearings, lug nuts, axle housing etc. But maybe iv totally missed what youre saying. :confused2:
larry

Perhaps.
I'm saying that the point I am computing the stress at is the flange face and the tire to the right would be rotating or applying stress in the opposite direction. This is an oversimplification of course as the bottom of the flange would undergo resistance from the tire and rim not yielding to a downward rotation which I ignored. But hey the last statics class I took was in 1975 and I am amazed that I remember this much of it as I only got a C in it. I fully expect an 2005 plus A student with an app on his phone to pop in at any time and correct my errors. As far as I know though gravity still works just the way it did in 1975.

 

[texasjohn]

OK, time for an update.

I got my local tire place to retrieve the fumbled tire stems and insure the new ones were properly installed. Inflation of industrial skid steer tires is to 60 PSI, max is 65 PSI. So, rims now fully capable of being mounted either way without interference with axle housing or king pin.

I called my other Kubota dealer, they've been in tractor sales/repair business since before there was 4 wheel drive, and posed my question of reversing the tires/rims for additional width. He understood the question. They've been Kubota dealers for excess of 15 years now. He didn't see that there would be a problem, although I did get a lecture regarding being careful on slopes. I pressed him, to the point of embarrassment, about problems that might arise from doing this. Would it tear up the bearings or seals? He didn't see that there would be any problem. Had they seen problems with seals/bearings on 4wd tractors over the years that could be explained by reversed rims? No, not that he could recall.

So, I mounted mine reversed and went out with the scraper to see if I could perceive any additional stability. Spent about 2 hours in same location as prior scraping.
My impressions are subjective, no scientific technique seem to be available other than simply the number of times I concentrated and felt concerned regarding tippiness when turning down hill. I have to say that I think it was slightly improved. There were a few times when I thought that the inside wheel would dip further down and things would be more unstable than they actually turned out to be. ...So overall, a possible improvement from a stability standpoint...clearly, did not get worse. An unanticipated result is that the front tires are now easier to see and judge where they will go, both right and left, since they are a couple of inched wider stance now on each side.

So, current score is....
2 dealers do not see a problem doing it
several manuals say don't for other models, but don't give a reason why
Numerous TBN members are dead set against it with dire warnings about the outcome.
All agree that side slope stability is something to be very careful about.
There is animated discussion about whether the extra width will or will not result in better stability, however slightly.

Me? I'm still kinda on the fence....thinking that I might leave them reversed for current task which encounters uneven conditions and slopes, then put them back when this task is over....so, stay tuned....

 

[TripleR]

Well if you're going to take the word of people who sell and work on these things...personally I NEVER do anything the manual advises against.:laughing::laughing::laughing: