Broken Welds on L344 loader

Templeton

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BX2380 FEL, MMM
Jan 19, 2020
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Bendigo australia,
Just noticed this morning the welds mounting the central hydraulic ram on the back of my L344 Kubota loader bucket have broken around three sides of the mount. About 150 hours old.
So,
1. what am i doing wrong, or is this a construction fault?
2
IMG_20201228_131221.jpg
IMG_20201228_131249.jpg
views from inside the bucket, 3rd pic is the back (ram) side.

2. IMG_20201228_131221.jpg IMG_20201228_131230.jpg IMG_20201228_131249.jpg
What should i look for in a repair?
 

Nicfin36

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I would say it is a manufacturing defect, but I am just speculating as I am not an expert. It is still under warranty I assume? I would reach out to the dealer about that.
 
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armylifer

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It would depend on what you were doing with it when it broke. I cannot see the whole bucket but it looks to me like it was used as a plow with the bucket fully in the down position. I think that would not be covered.
 
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PoTreeBoy

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Looks more like punching through the bucket than a weld defect.

Are you by chance back-dragging with the edge of the bucket?
 
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Templeton

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BX2380 FEL, MMM
Jan 19, 2020
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Bendigo australia,
Thank you all so much for the speedy responses.
I did use the bucket a few weeks ago to dig and curl out some big Agapanthus clumps.
And yes, I have used the edge of the bucket to back drag and pull my compost heap apart.

Just looking at the images again, it has broken around the weld rather than through the welds,

What should I look for in a repair job?
should I get a reinforcing plate welded on the inside of the bucket?
T
 
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Fordtech86

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I would tend agree with misuse, but if tractor under warranty it wouldn’t hurt to try. Tractor financed and have the Kubota insurance? If so I’m sure they would cover it minus your deductible
 
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PoTreeBoy

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Thank you all so much for the speedy responses.
I did use the bucket a few weeks ago to dig and curl out some big Agapanthus clumps.
And yes, I have used the edge of the bucket to back drag and pull my compost heap apart.

Just looking at the images again, it has broken around the weld rather than through the welds,

What should I look for in a repair job?
should I get a reinforcing plate welded on the inside of the bucket?
T
Bevel grind out the crack, straighten and re-weld. Doubler patch if you want.
Ease up on the back-dragging. You're lucky it hasn't buckled the cylinder rod.
 
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SidecarFlip

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Bevel it, jig it, weld it and fish plate it on the inside of the bucket with a rectangular piece of metal at least the same gauge as the back sheet and overlapping the welded area by an inch or so.

I've never been fond of the single cylinder bucket arrangement anyway. To me it's another Kubota cheap out. Way too much localized stress.
 
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Nicfin36

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I've never been fond of the single cylinder bucket arrangement anyway. To me it's another Kubota cheap out. Way too much localized stress.

I did not realize it was a single cylinder. Makes sense how each side of the loader/bucket can be worked back and forth fatiguing the metal with the middle cylinder arrangement.
 

SidecarFlip

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Having rebuilt more than one Kubota front loader bucket from induced stress and broken / failed welds in the past, one thing I've noticed and that is, the back sheets on the Kubota lighter duty material buckets) are not very thick to begin with and then having that single curl cylinder smack in the middle of that light gauge back sheet with no gusseting at all is an invitation for fatigue disaster. (as the one in the OP's picture displays). I realize that they are only used on the small tractors but you can still impose high stress to the bucket when shoving it into something not easily moved or back dragging with the bucket lip down.

Why if it was mine, I'd bevel out the tear area, weld it up, grind the weld flush with the bucket back sheet on the inside of the bucket and apply a 'fish plate' overlay at least the same gauge as the backsheet and overlap the the fatigued tear by a few inches and of course use some caution when using it. It is, after all, a material bucket for moving material, not excavation work,
 
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Henro

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Bevel it, jig it, weld it and fish plate it on the inside of the bucket with a rectangular piece of metal at least the same gauge as the back sheet and overlapping the welded area by an inch or so.

I've never been fond of the single cylinder bucket arrangement anyway. To me it's another Kubota cheap out. Way too much localized stress.
Being someone that only welds occasionally, I have a question on the steps one would use repairing this with a fish plate on the inside.

I would be inclined to V-out the cracked portion, and then weld in a fish plate on the inside of the bucket first, before welding the crack together, with the weld in the cracked area also tying those pieces to the fish plate.

How would one, that knows what’s he is doing, do it?

Edit, I think on reread Flip said how he would do it. V it, weld on inside, grind smooth, weld on fish plate. So I guess my question boils down to asking what would be wrong with doing it the way I imagined?

(And Flip, I do not plan on playing with the mini ex until spring 😀)
 

Donystoy

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I've never been fond of the single cylinder bucket arrangement anyway. To me it's another Kubota cheap out. Way too much localized stress.
[/QUOTE]

I totally agree. I cannot see how that design would not eventually fail. The aftermarket KW loader that I got 35 years ago has two cylinders. I immediately altered the end stop plates that stop the bucket curl so as not to put force on the cylinders. I also welded an angle iron to the top of the bucket for reinforcing as well as a receiving tube for when I use the loader as a crane.
I also regularly back drag and have never had any issues.
 

SidecarFlip

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Being someone that only welds occasionally, I have a question on the steps one would use repairing this with a fish plate on the inside.

I would be inclined to V-out the cracked portion, and then weld in a fish plate on the inside of the bucket first, before welding the crack together, with the weld in the cracked area also tying those pieces to the fish plate.

How would one, that knows what’s he is doing, do it?

Edit, I think on reread Flip said how he would do it. V it, weld on inside, grind smooth, weld on fish plate. So I guess my question boils down to asking what would be wrong with doing it the way I imagined?

(And Flip, I do not plan on playing with the mini ex until spring 😀)

Whichever way blows your dress up. Considering the gauge of the backsheet (not heavy), I'd take a flap disc in my angle grinder and remove all the surrounding paint first and have a good look at the crack and then determine if it indeed needed a bevel or could just be welded from the backside first, then another weld applied from the frontside and then ground down flush with the backsheet so the inner repair would accept a fishplate and lay flat. Take the flapwheel again and remove all the surrounding paint on the inside and then lay in a fish plate from material of the same gauge as the backsheet,, corner tacking it and insuring that it's laying flat to the existing sheet before welding it together and not continual weld either because continual weld will cause the fish plate to warp. No root weld and stringers needed because the metal is thin to begin with.
 

whitetiger

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I've never been fond of the single cylinder bucket arrangement anyway. To me it's another Kubota cheap out. Way too much localized stress.
I totally agree. I cannot see how that design would not eventually fail. The aftermarket KW loader that I got 35 years ago has two cylinders. I immediately altered the end stop plates that stop the bucket curl so as not to put force on the cylinders. I also welded an angle iron to the top of the bucket for reinforcing as well as a receiving tube for when I use the loader as a crane.
I also regularly back drag and have never had any issues.
[/QUOTE]
Yet there are literally thousands of BX tractors out there used just as hard with no problem at all. Must not be all that bad of design after all.
If you would bother to look around, several manufactures of small loaders use a single tilt cylinder.
 
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Henro

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I totally agree. I cannot see how that design would not eventually fail. The aftermarket KW loader that I got 35 years ago has two cylinders. I immediately altered the end stop plates that stop the bucket curl so as not to put force on the cylinders. I also welded an angle iron to the top of the bucket for reinforcing as well as a receiving tube for when I use the loader as a crane.
I also regularly back drag and have never had any issues.
Yet there are literally thousands of BX tractors out there used just as hard with no problem at all. Must not be all that bad of design after all.
If you would bother to look around, several manufactures of small loaders use a single tilt cylinder.
[/QUOTE]

I remember years ago (While in Japan) seeing some very heavy duty equipment using a single cylinder on the front bucket.

It is all in the design I think. Nothing inherently wrong with a single cylinder design, if properly done.

So the question is whether Kubota is lacking in their design or not. Perhaps use that causes the connection to the bucket to fail falls under abuse by Kubota design standards. Do not know...
 

Templeton

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BX2380 FEL, MMM
Jan 19, 2020
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Bendigo australia,
I suspect that the issue started about 3 weeks ago when I was speeding along with the bucket curled down, and accidentally hit the drop lever, meaning the bucket lip hit the ground quite hard at speed. That would have bent the failure point in the opposite direction, but it could well have initiated a crack, and I suspect subsequent use of the bucket has bent the mounting spot as shown.

Thank you all for your advice regarding repair. Such work is beyond my welding skills, but it gives me great information to start the discussions with the workshop. Hope they are open between Xmas and new year - my compost needs turning :)
T
 
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xrocketengineer

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I am no expert but, the failure looks like if the material of the bucket is brittle, due to the rough cracked edge . There is no deformation (bending) nor fatigue with a polished/rubbed edges. I would assume that the material of the bucket should be ductile, in other words it should deform first and then fail (break).

1609188283112.png

1609188452615.png
 
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beckmurph

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I suspect that the issue started about 3 weeks ago when I was speeding along with the bucket curled down, and accidentally hit the drop lever, meaning the bucket lip hit the ground quite hard at speed. That would have bent the failure point in the opposite direction, but it could well have initiated a crack, and I suspect subsequent use of the bucket has bent the mounting spot as shown.

Thank you all for your advice regarding repair. Such work is beyond my welding skills, but it gives me great information to start the discussions with the workshop. Hope they are open between Xmas and new year - my compost needs turning :)
T
Take the bucket back to your dealer. Let Kubota tell you if it is under warranty or not.
Kubota might be interested in this failure.
 
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