Kubota B2710HSD front axel sheared off.

[Redlined0002]

Check your tie rod ends. A wore out tie rod end will cause a axle to shear also.

 

[BlueKnife]

Think about 2 kids on a teeter totter, one heavy and close to the privet point, the other lighter but further away. If you try to lit the heavy end with no one on the other end you are lifting the entire weight, but as soon as there is some weight on the other side, no matter how much the amount you lift is less.
Think of a pry bar that lets you move a big rock. It's the same kind of idea.

Exactly. The thing that sort of throws a monkey wrench into this is that we have two potential pivot points for the teeter totter, the front axle or the rear. If we've got enough weight in the loader to take weight off the rear axle, (thereby transferring that load to the front) and we want to take weight off the front axle, we have to add enough weight onto the rear axle in order to not only get it back to the load at which it started but to get it heavy enough to change the pivot point from the front axle to the rear. If we just add weight to the rear till the rear weight is the same as when we're unloaded, we're not taking weight off the front. We have to exceed the unloaded rear weight enough to actually start pivoting on the rear axle in order to take weight off of the front.

 

[PETDOC]

Check your tie rod ends. A wore out tie rod end will cause an axle to shear also.

Thanks, will do. Although tractor will be 26 years old July 2025, it only has 844 hours of use and is stored in unconditioned shed when not in use. Having said that I live in foothills of the Great Smoky Mountain Natl. Park. Land is hilly to very steep so I'm often transporting loads up, down or across uneven terrain.

 

[M59]

Exactly. The thing that sort of throws a monkey wrench into this is that we have two potential pivot points for the teeter totter, the front axle or the rear.

It gets worse than your reply, although your reply points out a significant deficiency in teeter totter similarity. The teeter totter is for all intents is a nearly rigid system unless you were to place two extremely heavy loads on teeter totter ends at which point bowing would occur in the beam.
The teeter totter fulcrum is a rigid point about which the beam rotates. The tractor has two fulcrums about which rotation may occur BUT only after the squishy tires substantially change their shape.

 

[PETDOC]

I replaced the left front axel today. I couldn't appreciate any physical difference between the replacement (4 lbs. 1.2 oz) and original axel (4 lbs. 3.6 oz). After cleaning the point of attachment of the axel to the wheel flange with a brass bristle brush I found rare short hairline cracks and some superficial pitting (more easily seen if the picture is expanded). Not sure when or even if it would fail. If the new axels last as long as the originals I’ll be at the century mark and unlikely still driving a tractor.

 

[M59]

Thanks for up date and pics. Looked at enlarged pic of the "old" hub and see annular series of pits but no cracks. Are the cracks you see radial or annular?

If the overloading were equally distributed across both front wheels, I would expect to see significant cracking in this hub, but I don't.

Perhaps the R hand failure was unique to that hub and for yet to be determined reason.

 

[PETDOC]

Thanks for up date and pics. Looked at enlarged pic of the "old" hub and see annular series of pits but no cracks. Are the cracks you see radial or annular?

If the overloading were equally distributed across both front wheels, I would expect to see significant cracking in this hub, but I don't.

Perhaps the R hand failure was unique to that hub and for yet to be determined reason.

When you expand the picture look very, very closely at near center slightly above a ridge. Beginning in the horizontal band of corrosion and extending upward slightly to the left you'll see a short tiny linear crack. If you look down and slightly to the left from that crack you will see another fainter, slightly longer crack angled in a similar direction. I used a pick to make sure they were cracks and not just a stray line. Not sure if they are significant or not. As you have pointed out there are a lot of unknown variables to consider in what caused my right axel to break. Having acknowledged that fact, I’ll sleep more soundly knowing that I replaced both axels; however, the tractor and I are long in the tooth so as Gilda Radner so famously said "It's always something."
I should add 3 things I've concluded based on this experience, focused research, Messick's YouTubes and comments to this thread are:
1. When things get old they can break.
2. While I now question if I ever exceeded the 880 lb load capacity of my FEL as a static load, I do believe the dynamic loads occurring while transporting full loads over uneven roads and over steep terrain, e.g., backing up a steep hill, likely did transiently exceed the front axel load capacity.
3. A counterweight attached to the 3 point hitch will significantly reduce the load on the front axels; however, filling the rear tires or adding rear wheel weights will only increase the load on the front axels.

I do have a theory on why the front axels may eventually break at the junction with the wheel flange. If you look at the picture of my original axel you will see a raised band of the axel with the corrosion/cracks only appearing adjacent to the junction near the flange. The raised band is where the axel is surrounded by a bearing with an oil seal (which I did replace). It did a really good job as I never saw any axel oil seeping through. Perhaps if that area was lubricated it would not have corroded.

 

[Sawyer Rob]

3. A counterweight attached to the 3 point hitch will significantly reduce the load on the front axels; however, filling the rear tires or adding rear wheel weights will only increase the load on the front axels.

You are gonna have to "splain" that one to me!

SR

 

[M59]

Petdoc,
I had good look at highly magnified lower pic of post #65 and both pics of post #1 and conclude that your right hand hub/ axle failure was a single dramatic event, likely overloading, due to Kubota's improper weld at axle to flange joint. Both post #1 pics show a annular brown band surrounding a white annulus. I believe the brown discoloration is indicative of a weld failure and joint created during manufacturing where the brown is oxidation of the metal and the whitish band is the recent crack and failure. Notice the radial cracks in the brown band are also brown indicative of a long ago failure that was open to oxidation but not sufficiently open to allow water entry to cause pitting.
If the weld failure was an ongoing process, you would see significant burnishing of the brown oxidized annulus due to flexure of the failing joint

I do not see the above sort of failure in the recently removed left hub which reinforces my opinion of a one off manufacturing failure. If you bought the tractor used then it is also possible the left hub had failed and was replaced and therefore has fewer hours on it.

Given other TBN members have brought up axle failure, I suspect Kubota or a subcontractor had some manufacturing/ quality assurance issues.

 

[PETDOC]

Petdoc,
I had good look at highly magnified lower pic of post #65 and both pics of post #1 and conclude that your right hand hub/ axle failure was a single dramatic event, likely overloading, due to Kubota's improper weld at axle to flange joint. Both post #1 pics show a annular brown band surrounding a white annulus. I believe the brown discoloration is indicative of a weld failure and joint created during manufacturing where the brown is oxidation of the metal and the whitish band is the recent crack and failure. Notice the radial cracks in the brown band are also brown indicative of a long ago failure that was open to oxidation but not sufficiently open to allow water entry to cause pitting.
If the weld failure was an ongoing process, you would see significant burnishing of the brown oxidized annulus due to flexure of the failing joint

I do not see the above sort of failure in the recently removed left hub which reinforces my opinion of a one off manufacturing failure. If you bought the tractor used then it is also possible the left hub had failed and was replaced and therefore has fewer hours on it.

Given other TBN members have brought up axle failure, I suspect Kubota or a subcontractor had some manufacturing/ quality assurance issues.

You very well may be right. The junction is obviously a weld site. I did purchase the tractor new. When the right axel sheared off the loader bucket was empty, but the separation may have already started. The morning it occurred it was below freezing. After allowing the tractor to warm up I had driven at a very low speed about 30 yards when the wheel suddenly began to turn outward then separated-all within a single rotation. My initial thought was the bearing seized up, but that was not the case.

 

[PETDOC]

You are gonna have to "splain" that one to me!

SR

Regarding the effect of a counterweight on the 3 point hitch is well demonstrated with scales under the front and rear wheels in the Messick’s YouTube linked in post #3. You may have a valid question regarding my conclusion of the effect of increasing weight in/on the rear wheels. My belief is that in a static situation likely all weight below the rear axel does not increase load on either the front or rear axles, whereas rear wheel weight above the axel will increase load on the rear axel and likely have a small amount transferred to the front axel; similar to you sitting in driver's seat, where the majority of your weight would be borne by the rear axel, but some would be transferred to front axel. I can't see how weight directly on the rear axel would act as a fulcrum and unweight the front axel, but if you hang it off the rear of the tractor it does shift weight from the front to the rear axel. In a dynamic situation the movement of the liquid weight in the rear wheels may or may not change the weight distribution. I received a C and a B, respectively in 2 semesters of college physics and those grades were a gift because of the class curve so my conclusions may be wrong. Certainly welcome other thoughts.

 

[rScotty]

You are gonna have to "splain" that one to me!

SR

SNIP......similar to you sitting in driver's seat, where the majority of your weight would be borne by the rear axel, but some would be transferred to front axel. I can't see how weight directly on the rear axel would act as a fulcrum and unweight the front axel, but if you hang it off the rear of the tractor it does shift weight from the front to the rear axel.

That's a nice explanation.

 

[PETDOC]

Regarding the effect of a counterweight on the 3 point hitch is well demonstrated with scales under the front and rear wheels in the Messick’s YouTube linked in post #3. You may have a valid question regarding my conclusion of the effect of increasing weight in/on the rear wheels. My belief is that in a static situation likely all weight below the rear axel does not increase load on either the front or rear axles, whereas rear wheel weight above the axel will increase load on the rear axel and likely have a small amount transferred to the front axel; similar to you sitting in driver's seat, where the majority of your weight would be borne by the rear axel, but some would be transferred to front axel. I can't see how weight directly on the rear axel would act as a fulcrum and unweight the front axel, but if you hang it off the rear of the tractor it does shift weight from the front to the rear axel. In a dynamic situation the movement of the liquid weight in the rear wheels may or may not change the weight distribution. I received a C and a B, respectively in 2 semesters of college physics and those grades were a gift because of the class curve so my conclusions may be wrong. Certainly welcome other thoughts.

Found a good link on TBN regarding weight distribution under different loads.

Tractor ballasting, weight distribution & free body diagrams

A discussion about this came up in the New Holland forum. I though I'd repost it here as I spent a good chunk of the evening writing it up. I know, shame on me for double posting, but I think it deserves to stand on it's own. I'm sure Dad would like to see me putting my engineering education...

www.tractorbynet.com

It appears rear wheel weight has no appreciable impact on front axel load, neither lighter nor heavier.
This seems logical to me. If I divide the rear tire into 4 quadrants with a vertical and horizontal line that transect the wheel's axel the 2 quadrants below the axel have minimal impact on the rear or front axel load, but the upper 2 quadrants would load the rear axel. When looking at a side view of wheel the forward upper quadrant will ever so slightly increase front axel load, but the rear upper quadrant would totally counterbalance that load, hence no net effect on the front axel.

 

[Sawyer Rob]

Found a good link on TBN regarding weight distribution under different loads.

Tractor ballasting, weight distribution & free body diagrams

A discussion about this came up in the New Holland forum. I though I'd repost it here as I spent a good chunk of the evening writing it up. I know, shame on me for double posting, but I think it deserves to stand on it's own. I'm sure Dad would like to see me putting my engineering education...

www.tractorbynet.com

It appears rear wheel weight has no appreciable impact on front axel load, neither lighter nor heavier.
This seems logical to me. If I divide the rear tire into 4 quadrants with a vertical and horizontal line that transect the wheel's axel the 2 quadrants below the axel have minimal impact on the rear or front axel load, but the upper 2 quadrants would load the rear axel. When looking at at side view of wheel the forward upper quadrant will ever so slightly increase front axel load, but the rear upper quadrant would totally counterbalance that load, hence no net effect on the front axel.

WEEEEEEW, and I was just about to go out and drill big holes in the rear tires on my loader tractor, just to take the weight off the front axle!!

SR

 

[RayIN]

And i got up and turned on my computer because I couldn't sleep. Think I can now; g'night again.