LA724 frame break

[pottsm2639]

Anybody ever seen something like this before. Can it be welded or am I out $950 ?
I was not doing anything reckless, just moving a dirt pile. I was going slow and steady. When I lifted a load I heard it pop and loader shifted. Any ideas what I did wrong? I didn't see any hairline cracks prior but may have missed it.

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[D2Cat]

I can't tell for sure, but it looks like there are different colors at the break. On the side toward to toe, is that some slight rust there?

I would guess it was cracked at some point earlier and it gave up when you heard the pop.

If you don't weld, take it to a professional welder. He can grind a chamfer, weld it, and probably add a plate to strengthen it.

When you have iron and some room to work you can just about make anything work!! You're not out $950.

 

[torch]

A couple of wraps of duct tape and she'll be good as new...

Ok, maybe not.

If you are asking if that material can be welded, then yes it can. I'd V out both sides and alternate each pass until it was filled. Then I'd reinforce both sides too, since the weld repair will never be as strong as the original material, and the original material was not strong enough.

Depending on how old it is, it might be worth talking to the dealer. That certainly appears like there may have been a defect in the steel.

 

[maclean]

And now's the time to have that professional welder put a chainsaw mount on that arm.

I'm with check with the dealer...that looks like an old crack that finally broke...as D2Cat mentioned.

How does the other side look? Did you bend any hydraulic cylinders?

-Mac

 

[rbargeron]

It's a poor design - there are built-in stress raisers near the failure point. The oblong hole is punched (a setup locator?), leaving reduced section and added residual stress around the hole. With the scab plate stopping at the edge of the hole, there's a large change in cross section, normally a design no-no. Stress there goes way up.

In a good repair, the oblong hole would be veed out, plugged and welded solid, another scab plate would be added, maybe reaching down and connecting to the tube to spread out the load.

This failed part should get a look by the factory rep. I'll bet that by now they know it's weak and a revised replacement might be in the works already. Kubota is a stand-up company - they might surprise you and cover the cost of a new one. Hope the dealer helps you resolve this failure.

 

[1970cs]

His dealer closed about 1.75 years ago, Dakins! But has a newbie to Kubota dealer opened in the same place. $930.60 list price for that main frame piece.

Either have professional welder do the work or see if you can get Kubota to policy that piece.

Pat

 

[scdeerslayer]

It's a poor design - there are built-in stress raisers near the failure point. The oblong hole is punched (a setup locator?), leaving reduced section and added residual stress around the hole. With the scab plate stopping at the edge of the hole, there's a large change in cross section, normally a design no-no. Stress there goes way up.

In a good repair, the oblong hole would be veed out, plugged and welded solid, another scab plate would be added, maybe reaching down and connecting to the tube to spread out the load.

This failed part should get a look by the factory rep. I'll bet that by now they know it's weak and a revised replacement might be in the works already. Kubota is a stand-up company - they might surprise you and cover the cost of a new one. Hope the dealer helps you resolve this failure.

I had the same thought about the hole and plate. Didn't know it was called a scab plate though.

 

[BAP]

I would find a dealer and have them contact the Kubota Service Rep for your area. Looks to me it failed at a weld which could be a manufacturing flaw.

 

[bucktail]

While it technically failed at the weld, it's a design flaw not a manufacturing flaw for reasons already stated. The weld held up as it should have.

 

[pottsm2639]

Thanks for all the input. I will reach out to the dealer and hope for kubota to help. I'm very surprised that this happened. Ive never abused it, and have always kept up on my maintenance schedule. I can't believe this frame support would give out before a hydraulic line or cylinder. It seems crazy that the weakest link was a solid steel frame member.

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[Tooljunkie]

In this case it looks like a built in failure as mentioned.
If it comes to the part being repaired,have the same repair performed on other side.
You may not have been hard on it, but let some redneck on it for 10 minutes and could be what did it.

I do know a guy that could wreck an anvil, i would never let him near any of my stuff.

Good luck, hope kubota comes through for you.

 

[Diydave]

A good welder could fish plate that on both sides, for way less than the price of the new part...

 

[85Hokie]

Exactly what I was thinking ---- "If it comes to the part being repaired,have the same repair performed on other side. "

I have never seen something like that give - I would think it is very rare on a kubota! I think it is an easy fix, and once fixed, it will be stronger (way stronger) that it was when it rolled of the line.

If you go welder route, I bet it will be a couple of c-notes, but it will be a good solid fix, if Kubota fixes it, I hooooopeee that the same part is not placed back in! - If this had happened before, it would be a redesigned part.

 

[Alphonse]

Post #5 Sums it up pretty well.
It is a design flaw.
You have cast steel for the frame mount and HAZ right at the section transition. Judging from your pic the join weld wraps the corners only, so the designers were half fast thinking about what might happen.
If you are a welder, I would suggest a tension strap on the outside, from lower "pipe" to midpoint of upper bushing with weld wrapping the ends only, after the deal is welded up. All the edges of that side should be undercut free and void of any gouges, grinder or otherwise, almost polished.
The oblong hole shouldn't have been an issue.
If you are not a welder, find a good one. Lots of wannabes.
Don't tell him/her what to do, but you can ask questions.