Front tires caused axle failure...?

[/pine]

Dang I guess every tractor out there in the world with smaller front tires is going to destroy it's self seeing as almost anyone that does enough hours and work on them will wear out the smaller fronts faster then the rears. Then on top of that I can vary the loaded radius depending on weather a load is being carried for transport or pulled to work, a heavy tongue load will lift the front increasing the front loaded radius and squat the rear decreasing the loaded radius which is a considerable change in the lead lag effect.

I would bet that in some cases that the effect is so gradual (like with the the wear of tread etc.) that any damage could be self canceling by wearing any binding parts equally... I've a seen a number of posts where owners report ground metal in their gear oil without any symptoms or apparent problems...
In post #5 I related a simple way to actually test and see if the lead-lag is possibly causing a future problem...

Obviously there is some measure of forgiveness beyond the ability of ground breakup under the bind...but whether you want to recognize it or not the lead-lag is there and it can/will cause damage...If it were not a fact it would not be acknowledged by manufacturers and cited in operator manuals etc. and be typically common knowledge among experienced operators...most of the folks on TBN are aware of the fact...it's not like it's a myth...!


BTW...if you want others to take you more seriously when it comes to general knowledge you should learn the difference between terms like "it's self" and itself....FYI "it's" is a contraction for "it is" just sayin...

 

[LouNY]

Thanks for the spelling lesson :shocked:

 

[Oldpath05]

Dang I guess every tractor out there in the world with smaller front tires is going to destroy it's self seeing as almost anyone that does enough hours and work on them will wear out the smaller fronts faster then the rears. Then on top of that I can vary the loaded radius depending on weather a load is being carried for transport or pulled to work, a heavy tongue load will lift the front increasing the front loaded radius and squat the rear decreasing the loaded radius which is a considerable change in the lead lag effect.

The smaller tires on front is geared in sync with the larger rear tires on tractors, therefore when I have AG 11.2-24 on the rear and 7-16 on front, going down to a 15" or up to 17" on front will throw the front gearing speed out of sync and forces more wear on the drivetrain, the same with pickup trucks, if a 4x4 came with 18" tires your put the same size on front and rear and preferably the same brand.

Right tire size is everything for the designed gear ratio on a 4x4 tractor and further more you shouldn't put two different size tires on the rear end either, it will increase wear&tear and cause you to go in circles.....

 

[thoner7]

What kind of help did you ask for, they should've given you tire size specs with tire options.

They just sent me tire R1 R4 and Turf tire sizes listed in the manual, while ignoring my whole question about the 15x19.5 tires.

Did they start leaking oil before the catastrophic failure? When my L5740 started leaking oil onto the inside of the rims, I checked here and found it not unusual when doing a lot of loader work like load and carry. As I caught it early, no damage other than failed bearings. My dealer said he has one customer who brings the drives into the dealership as they fail (yes, it is that frequent). They replace the bearings, he reinstalls and goes on.

The axle shaft is like a lever working on the bearings. If the center of the wheel is over the midpoint of the bearings, the bearings are loaded equally. Widen the tire and that load line moves away from the midpoint. If it痴 outside the outer bearing, the outer bearing is handling all the load designed to be carried by 2 bearings. Move the load point out further and the outer bearing is loaded even more than the weight carried by the wheel due to leverage. Bearing life is a factor of the cube of the load so just a little shift causes a large reduction in bearing life.

Your tire radius difference is insignificant. Your tire width is very significant. But the tractor went 3600 hours before failure. I do realize that part of those hours were with the standard size. If you replace the bearings before they fail to the point that they damage the gear, you can keep using the wide tires. Kubota uses that style final drive on the front in order to get a tight turn radius. My M7 has much wider fronts than the drive tires on my L5740. To make it work the M7 has a different style final drive - a planetary - and the turn radius is a country mile. But it can withstand the load. However it is not robust enough to use duals on the front like you see on so many over 250 HP tractors.

The following is an excerpt from diagnosing failures like yours:


Increased Offset Most oversize tires are on wheels that are offset so the tires don稚 rub. This moves the load on the bearing to the outside, so the load on the bearing is no longer centered.
Increased Leverage A larger tire is a longer lever. A heavier tire puts more force on the lever. A long lever with more force behind it puts greatly increased leverage on the bearing and hub.

There was no oil leaking from the hubs prior. Maybe I'll take a peak at the other side bearings

 

[LouNY]

I am well aware of how tractors are geared differently in the front and rear ratios to hopefully have the desired 3-5% lead in the front compared to the rear with the designed height (loaded radius) on them. The loaded radius is the determining fact on how the tires work you can change rim diameters and tire profiles and maintain the proper tire ratios it is done quite often for many different reasons.

 

[Oldpath05]

They just sent me tire R1 R4 and Turf tire sizes listed in the manual, while ignoring my whole question about the 15x19.5 tires.

Did you change the front size without changing the rear size to.............Maybe a local dealer would be more helpful. I looked up Kubota m5400 on Tractor Data and dont show that size for some reason>4WD Standard tires (ag):>Front: 9.5-22. Rear: 16.9-28.
TractorData.com Kubota M54 tractor dimensions information

But on the other hand Tractor Data shows different tire options for my L3400>> TractorData.com Kubota L34 tractor dimensions information
AA year after I bought my tractor with AG tires I didn't like how they sink in soft ground so quick and ask the dealer if I could change the fronts from 7-16 to the wider Industrial tires, they said sure long as I change the rears to which meant changing to all 4 different rims, but then my rear chains wont fit and bla bla bla, from what I know you change one thing then 15 other things have to be changed, domino effect............

 

[Oldpath05]

Dang I guess every tractor out there in the world with smaller front tires is going to destroy it's self seeing as almost anyone that does enough hours and work on them will wear out the smaller fronts faster then the rears. .

I am well aware of how tractors are geared differently in the front and rear ratios to hopefully have the desired 3-5% lead in the front compared to the rear with the designed height (loaded radius) on them. The loaded radius is the determining fact on how the tires work you can change rim diameters and tire profiles and maintain the proper tire ratios it is done quite often for many different reasons.

Maybe I didn't read it right but your former post suggest different to me, I have smaller front tires on my compact tractor and it's hardly ever in 2 wheel drive, actually thats what it really is because of the open differentials front and rear.

 

[Egon]

Seems there are many four wheel drive tractors out there that do last for a long time if conformed to the manufactures specifications.

Put an inordinately wide front tire on causes stress on the axle imposed by differential forces when turning. The inside of the of the tire cover very less distance than the outside of the tire does. Creates stress! Pretty simple.

 

[rScotty]

I am well aware of how tractors are geared differently in the front and rear ratios to hopefully have the desired 3-5% lead in the front compared to the rear with the designed height (loaded radius) on them. The loaded radius is the determining fact on how the tires work you can change rim diameters and tire profiles and maintain the proper tire ratios it is done quite often for many different reasons.

I think you mean Rolling (loaded) Circumference rather than Loaded Radius. LC is for calculating lead/lag ratios. LR is for ground clearance.
The confusion comes about because in one special case - that being for a perfect circle - radius & diameter are related to circumference by pi. But that's not the case for a loaded tractor tire.

 

[LouNY]

No I meant the loaded radius, the loaded circumference can be calculated from the loaded radius. The loaded radius is easier to measure with a stationary tractor.
The loaded radius is affected by load and tire pressure which in turn affects the loaded rolling circumference.
The taller the sidewall of a tire the more loading and pressure can effect those values.
When you get into taller tires it can easily be seen how inflation affects loaded radius or loaded rolling circumference,
You can reduce or increase the lead lag ratio by varying tire pressure, with a radial 30" or larger tire the loaded radius can change by a half an inch.

 

[rScotty]

No I meant the loaded radius, the loaded circumference can be calculated from the loaded radius. The loaded radius is easier to measure with a stationary tractor.
The loaded radius is affected by load and tire pressure which in turn affects the loaded rolling circumference.
The taller the sidewall of a tire the more loading and pressure can effect those values.
When you get into taller tires it can easily be seen how inflation affects loaded radius or loaded rolling circumference,
You can reduce or increase the lead lag ratio by varying tire pressure, with a radial 30" or larger tire the loaded radius can change by a half an inch.

How would you go about calculating the rolling circumference from a loaded radius? I'm willing to believe that it can be done, and the more I think about it the more I would like to learn more about it.

First things first.... I am using the term "loaded radius" to be the vertical distance from the center point of the axle to the surface of the ground. That distance is basically ground clearance. It will vary with load as the tire squats, but will remain constant as long as the load doesn't change. And part of the tire is flat against the ground.

So a bug crawling around the circumference of that tire would be traveling in an ellipse with one flat area. The distance he crawls around that ellipse plus the length of the flat area against the ground is the "rolling circumference".

I'm naturally lazy, and have never really got down and worked out a formula complex enough to solve the relationship between a changing radius and the resulting circumference. You see that sort of thing in orbital math where the distance an object moves in a path can be calculated in spite of the fact that the path is elliptical. So the path of an ellipse is a solvable relationship, especially if we ignore the flat spot where it meets the ground and the fact that the ellipse changes with load and pressure.... although it's getting ugly....

To keep things simple, I'd probably do what the manufacturers do and say that the formula only works for one specific tire at one pressure. That's how they give both static loaded radius and dynamic rolling circumference in their specs. So there's a relationship, but it sure isn't pi. My bet is it is just an average relationship that only works for their tires over a small range of loads and pressures.

Of course there is a simpler way. You can always measure to create specs. It may be that manufacturers measure both rolling circumference and loaded radius instead of trying to calculate one from the other. That's what I do. Then there's no need for some exotic formula. Measuring is easy to do and always right.
rScotty

 

[Oldpath05]

Loaded or unloaded radius makes very little difference, the only way that become an issue is if one put 100pis in rears and 10psi in front. Right tire size is what to go by, the OP didn't put right tire size on front of the tractor, you cant change front without changing rear to factory specs. That's why when the dealer told me I could go with R4 or turf tires I'd have to change front and rear at the same time, width is also is a none issue unless you double up the fronts, it is and always be radius in on tires. that's my point and I'm sticking to it, everything else is fake news...........

 

[LouNY]

It is the same basic formula as for any circle;
C=2*PI*r or C=2r(pi) with Pi being roughly 3.14
So if the exact centerline of a tire and rim combination can be found and measured to the ground or floor.
A 20.8R-42 can have a static rolling radius of 34.5" and a stated Rolling Circumference of 228 Inches.
You can vary that considerably with just a 5-10# air pressure change.
But ; 2*{pi}3.14 * 34.5" = 216.66"
the same as 2*34.5"*3.14= 216.66"
And yes you certainly can just measure to get the rolling circumference, mark the tire and ground and roll it exactly one revolution and mark and measure the distance on the ground.

 

[LouNY]

Loaded or unloaded radius makes very little difference, the only way that become an issue is if one put 100pis in rears and 10psi in front. Right tire size is what to go by, the OP didn't put right tire size on front of the tractor, you cant change front without changing rear to factory specs. That's why when the dealer told me I could go with R4 or turf tires I'd have to change front and rear at the same time, width is also is a none issue unless you double up the fronts, it is and always be radius in on tires. that's my point and I'm sticking to it, everything else is fake news...........

Well it's a good thing that we can agree to disagree.
It is amazing the difference in radius or circumference between different tires of the same size and type but different manufacture and models.
One of the tractors on the farm had such a mismatch of tires from the factory that it would lurch tremendously engaging or disengaging 4wd,
They went through several sets and brands of tires to get an acceptable set all of the same sizes per the sidewalls.

 

[Oldpath05]

:thumbsup:I love agreeing to disagree, makes a great discussion that most cant appreciate, but yeah same brand sometimes make a difference to......

 

[the old grind]

I suspect the PO likely drove those gears to near death in FWA mode (>3khrs is plenty) and suggest that s__ falling apart was as coincidental to the tire replacement as causal.

 

[thoner7]

Does anyone know the bolt pattern for the front wheels? I just measured 6 1/8 6 lug with a 4 5/8 center hole. .maybe I was a tad off but that's quite close to a typical 6 lug 4 1/2 center hole which is quite common.

I assume they are a metric size being a Japanese tractor?

 

[Oldpath05]

Gee wiz that to me is a strange question, the bolt pattern is already there on the wheel and hub.

 

[thoner7]

Gee wiz that to me is a strange question, the bolt pattern is already there on the wheel and hub.

Thanks for your well thought out advice.

 

[Smokeydog]

Wonder how many times the front axle oil was changed? FEL and 4wd work requires maintenance.