HELP! My Backhoe won't swing left!

[rScotty]

Bueller?

Well, I had to look up "Bueller" online. It's not a rural or western term. I'd never heard it. Weird.

"Google Search: What does it mean to say Bueller?
Goodle Answer: Bueller: Interjection. Expression used to convey waiting for a response when there is none."


But on to the cylinder. I am very impressed at your coworker's theory. I like the guy's go for it attitude on diagnosis. Plus I never did like the "piece of crud stuck somewhere" theory. It just didn't make sense given the velocity of that hot hydraulic oil.

But I guess I'm also surprised that we haven't heard of it here on TBN. Did he just find this out? Has he posted it anywhere? What was the response there?? Did he contact Kubota? What did they say??

This seens to be the first time anyone has actually gone after solving this TBN problem and I'm stunned by what he found. And as I think about it it brings up even more questions.

What he found could be huge! We already know that Kubota had a unpublished recall for some of their TBN boom cylinders that came apart internally. I was the recipient of a replacement boom cylinder after the warranty was expired - and no questions asked. Could there be any connection? Is this the same cylinder mfg? Did Kubota make those cylinders or were they outsourced.
And what's your co-worker going to do? Has he talked to Kubota? That would be my first move. The previous factory cylinder replacement was NOT a publicised recall.

Then there's the mechanical questions....What really happened inside the cylinder and why? Did that shaft break or did a nut come loose? Can't tell from the pictures. Can he just screw it back together? How is the shaft affixed to the piston? Is there damage to the inside wall? Is Kubota interested?

And we need to figure out a simple way to tell if other Kubota TLBs have had the same thing happen. Some kind of test we all agree about that can be done without having to take the cylinder out and apart. Any ideas on that? What's simple & 100%?
rScotty

 

[avc8130]

Well, I had to look up "Bueller" online. It's not a rural or western term. I'd never heard it. Weird.

"Google Search: What does it mean to say Bueller?
Goodle Answer: Bueller: Interjection. Expression used to convey waiting for a response when there is none."


But on to the cylinder. I am very impressed at your coworker's theory. I like the guy's go for it attitude on diagnosis. Plus I never did like the "piece of crud stuck somewhere" theory. It just didn't make sense given the velocity of that hot hydraulic oil.

But I guess I'm also surprised that we haven't heard of it here on TBN. Did he just find this out? Has he posted it anywhere? What was the response there?? Did he contact Kubota? What did they say??

This seens to be the first time anyone has actually gone after solving this TBN problem and I'm stunned by what he found. And as I think about it it brings up even more questions.

What he found could be huge! We already know that Kubota had a unpublished recall for some of their TBN boom cylinders that came apart internally. I was the recipient of a replacement boom cylinder after the warranty was expired - and no questions asked. Could there be any connection? Is this the same cylinder mfg? Did Kubota make those cylinders or were they outsourced.
And what's your co-worker going to do? Has he talked to Kubota? That would be my first move. The previous factory cylinder replacement was NOT a publicised recall.

Then there's the mechanical questions....What really happened inside the cylinder and why? Did that shaft break or did a nut come loose? Can't tell from the pictures. Can he just screw it back together? How is the shaft affixed to the piston? Is there damage to the inside wall? Is Kubota interested?

And we need to figure out a simple way to tell if other Kubota TLBs have had the same thing happen. Some kind of test we all agree about that can be done without having to take the cylinder out and apart. Any ideas on that? What's simple & 100%?
rScotty

Haha, old reference to Ferris Bueller's Day Off movie.

My coworker isn't a forum type. This happened to him last year. No reason to contact Kubota as the machine is 10+ years old. He just brought it to a local hydraulic shop and they fabricated a new shaft. $1000 later...

The shaft failed. The nut was still attached to the threads, but the threads broken from the shaft.

Well, I'm going to take my left cylinder apart. My L45 refuses to swing left now. If I find the same thing he found, I'm gonna guess everyone with the intermittent "no swing" probably has a similar issue.

ac

 

[avc8130]

rScotty,

Does anyone have any better explanation for what's going on?

I could pull the relief valve at the control for the left swing direction, but I think it's working just fine. I can hear fluid flow through the valve at partial activation, then once I get past ~33-50% of lever movement the hissing sound of flowing fluid goes away...likely because it's just flowing through the system freely?

ac

 

[rScotty]

Haha, old reference to Ferris Bueller's Day Off movie.

My coworker isn't a forum type. This happened to him last year. No reason to contact Kubota as the machine is 10+ years old. He just brought it to a local hydraulic shop and they fabricated a new shaft. $1000 later...

The shaft failed. The nut was still attached to the threads, but the threads broken from the shaft.

Well, I'm going to take my left cylinder apart. My L45 refuses to swing left now. If I find the same thing he found, I'm gonna guess everyone with the intermittent "no swing" probably has a similar issue.

ac

Wouldn't it be better to try a test first? There are a couple of problems with your coworker's theory and the posted pictures. That may be because they are still in process. I haven't looked at the hydraulic flow map, but I'm not sure that his theory with those pictures explains why the other cylinder isn't able to do all the work.

His drawings are beautiful. But I think if we were to move the position of the "extend port" more toward the center of the cylinder - slightly to the center of where he shows the piston seals, then his theory makes more sense. In that way it may be that the loose piston is able to somehow block some of the flow.

Revising the drawing also makes an alternate theory is possible for him. In that one, a loose piston might be able to move all the way to the end of the cylinder which allows the incoming flow to hydraulically lock both swing cylinders. I would have to look at the hydraulic schematic flow diagram to see if that is possible. I'm not the world's best at deciphering a hydraulic schematic - still studying it - so if anyone is then let me know.

But I think that if either of those theories are true, then simply capping the appropriate hose and cylinder on your tractor would make the remaining cylinder able to work again and confirm the problem.

Oh....also fitting an inexpensive inline hydraulic on/off valve would also do the same thyying.
rScotty

 

[rScotty]

I'm trying to remember who it was who reported that their new M59 (I think it was an M59) would only swing half as fast as he expected. In a thread a few months ago, he timed his and then I timed mine, and sure enough his backhoe is swinging only half as fast as mine for a full swing side to side at the same RPM.

I wonder if he is only working on one swing cylinder.... Or Am I?
rScotty

 

[avc8130]

Here are the hydraulic diagrams from the Kubota service manual.

 

[avc8130]

rScotty,

Does your hoe have decent power on swing? Can you pick the machine up and move it side to side? Can you push up against a tree and actually feel it? Mine is pretty weak...and so was my coworkers.

The pictures I made, they are just hacks with MS Paint off the best cross-section I could find on the internet. The exact placement of the ports and dimensions for the components may or may not accurately represent the Kubota.

I think the next step for me is to plumb around the left cylinder and see if it works.

ac

 

[rScotty]

rScotty,

Does your hoe have decent power on swing? Can you pick the machine up and move it side to side? Can you push up against a tree and actually feel it? Mine is pretty weak...and so was my coworkers.

The pictures I made, they are just hacks with MS Paint off the best cross-section I could find on the internet. The exact placement of the ports and dimensions for the components may or may not accurately represent the Kubota.

I think the next step for me is to plumb around the left cylinder and see if it works.

ac

Yes, mine has decent power in swing. No problem moving the whole tractor around with the backhoe; including swing. In fact, I do more sidesweeping than I should just because the swing works so well. But I'm still suspicious. After all, I did have that episode where it wouldn't swing one way even if it was years ago. I am fairly gentle on the backhoe. I run at half rated rpm and don't slam it around.

There are good M59 hydraulic schematics in good resolution in my shop manual.....although the M59 might not be the same as the L45?
I am a novice at reading hydraulic schematics. Just learning.
For anyone interested, FluidPowerWorld.com has an online tutorial on hydraulic symbology. Start with lesson 101.

Agree that plumbing would be a good diagnostic step. Or just put a manual valve inline. Surpluscenter.com has 7000+psi ball valves in the $20 range.

What is you feeling on why your co-worker's shaft broke? Only thing I can think of would be a tension failure.

 

[avc8130]

Yes, mine has decent power in swing. No problem moving the whole tractor around with the backhoe; including swing. In fact, I do more sidesweeping than I should just because the swing works so well. But I'm still suspicious. After all, I did have that episode where it wouldn't swing one way even if it was years ago. I am fairly gentle on the backhoe. I run at half rated rpm and don't slam it around.

There are good M59 hydraulic schematics in good resolution in my shop manual.....although the M59 might not be the same as the L45?
I am a novice at reading hydraulic schematics. Just learning.
For anyone interested, FluidPowerWorld.com has an online tutorial on hydraulic symbology. Start with lesson 101.

Agree that plumbing would be a good diagnostic step. Or just put a manual valve inline. Surpluscenter.com has 7000+psi ball valves in the $20 range.

What is you feeling on why your co-worker's shaft broke? Only thing I can think of would be a tension failure.

My feeling is that owners of the L39/L45/M59 all seem to experience this mysterious symptom where the backhoe stops swinging in one direction. For all of us, gravity motion and "bumping" has had some success "fixing" it. My coworker had the same experience, but refused to believe that this mysterious "solution" made any sense. Se he investigated and found stuff had actually failed. NO ONE else has any conclusive resolution to this phenomena.

A tension failure would make sense, but what would cause it? I'm pretty sure the hoe hits the stabilizers long before it runs out of swing travel on the cylinders?

 

[rScotty]

My feeling is that owners of the L39/L45/M59 all seem to experience this mysterious symptom where the backhoe stops swinging in one direction. For all of us, gravity motion and "bumping" has had some success "fixing" it. My coworker had the same experience, but refused to believe that this mysterious "solution" made any sense. Se he investigated and found stuff had actually failed. NO ONE else has any conclusive resolution to this phenomena.

A tension failure would make sense, but what would cause it? I'm pretty sure the hoe hits the stabilizers long before it runs out of swing travel on the cylinders?

My hat is off to him for taking his cylinders apart and having a look. Right or wrong, so far it is the only positive mechanical information that we have.

If not a solid stop, how about Hydraulic Shock? Given high RPM and a load in the bucket, could suddenly reversing the swing with the control levers create enough tensile force on that rod end to cause the failure?

And looking at the cylinder rod, we have to wonder what mods to piston and rod would make sense to increase the strength of the threaded portion? I'm sure your co-worker put some thought into that. What conclusions?

A shock-damping damping reservoir on a T in the pressure feed line would be another solution.

I will be fascinated to hear what you find in yours.

rScotty