More M59 repair fun.

   #1  

Hersheyfarm

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IMG_2496.JPG not sure why pics are sideways, but if you click on them they expand straight.

So the left side bucket cylinder top pin broke about 2 months ago. Broke right in half at the grease port. No biggie, because half of it slid out a little and I caught it. Today, not so lucky. Didn't notice that the other one broke in half, and half must of dropped out and boom. The cylinder pulled loose from the half of pin as it contracted, busting the steel line that feeds the hose and bending ears on the boom, and dousing me in about a half of gallon of fluid. Limped back to barn and begun beating boom ears back in place and draining remaining fluid from cylinder. Fun.

To date, both pumps went at about 70hr, the back bucket cutting blade/teeth ripped off, I have a crack thats back around the top pin of the driver side stabilizer I cut out and welded once, leaking seal on either transmission main shaft or front drive shaft, also numerous leaks around hoses. 720hr.

The pumps I don't know, maybe a fluke. Cant really blame the bucket, just one of those things. But the cracks, and braking pins, and leaks are a little much. Ive ran numerous full size, owned a 580 L for 11 years with no major issue. I'm wondering If this thing is better off for landowners instead of using it for a business. Its a great size and can really move dirt but...
 

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   #2  

Billrog

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That's something I've never heard of before how in the H do you break a pin. Working with it slid 1/2 way out?
 
  
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Hersheyfarm

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Yea, these pins have a bolt on one side that hold them in.
 
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Thats wild. I've never has issue one with anything (pins) or stabilizer arm mounts on either my M9 or 105X and I regularly abuse them both. In fact I have had no issues with either and the M9 is celebrating it's 10th birthday this spring.
 
  
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Hersheyfarm

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I think mine was contracted out to China.
 
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that pin looks like it has been broke for a while better check the others
 
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I think mine was contracted out to China.

Could be. Could be domestic steel poured in China too. It's very difficult to tell where it comes from, I'm in the steel business at my part time job (I'm retired from it mostly) and it's almost impossible to track the original mill. Could be. Right now, there is almost 200 million tons of excess steel floating around here, a lit of it Chinese in manufacture.

Think I'll pull my pins on the 105 and have a look-see. I don't want a failure with a 1500 pound round bale on the bale spear.

Looks to me like you kept ir well greased too so thats not an issue. You have way more grease piled in your weldment than I do.
 
   #8  

mike69440

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View attachment 463448 not sure why pics are sideways, but if you click on them they expand straight.

So the left side bucket cylinder top pin broke about 2 months ago. Broke right in half at the grease port. No biggie, because half of it slid out a little and I caught it. Today, not so lucky. Didn't notice that the other one broke in half, and half must of dropped out and boom. The cylinder pulled loose from the half of pin as it contracted, busting the steel line that feeds the hose and bending ears on the boom, and dousing me in about a half of gallon of fluid. Limped back to barn and begun beating boom ears back in place and draining remaining fluid from cylinder. Fun.

To date, both pumps went at about 70hr, the back bucket cutting blade/teeth ripped off, I have a crack thats back around the top pin of the driver side stabilizer I cut out and welded once, leaking seal on either transmission main shaft or front drive shaft, also numerous leaks around hoses. 720hr.

The pumps I don't know, maybe a fluke. Cant really blame the bucket, just one of those things. But the cracks, and braking pins, and leaks are a little much. Ive ran numerous full size, owned a 580 L for 11 years with no major issue. I'm wondering If this thing is better off for landowners instead of using it for a business. Its a great size and can really move dirt but...

IMHO, All TLBs should have about 10% more Good metal in them, including Pins and Bushing designed to resist wear and hard use. Kubota gets a premium for these machines, so tat should be part of the deal. So far my 10' hoe has stood up better than the loader pins and bushing.
 
   #9  

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Think you answered your own question. It's not a 580 backhoe made for heavy commercial duty cycles.
 
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mike69440

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Think you answered your own question. It's not a 580 backhoe made for heavy commercial duty cycles.

Not to happy with Kubota pricing right now, see Posts #15 & 16
http://www.tractorbynet.com/forums/...m59-front-drive-shaft-leak-2.html#post4420381

Kubota should spend a little less on advertising and take care of your problem

This is a design miscalculation of possible loads on the pin or a materials defect. The repair should be on Kubota's nickel. The engineer(s) who designed this disaster should hand carry the repair parts to you.

PS this is not Photo-Shopped
 

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Hersheyfarm

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I agree with you that the engineers really took weight saving into account with this machine. For me it would be hard to go back full size working in a mostly residential environment...but....

My machine is a 2008, and I have had it almost 6 years I think and put 720 hours on it. I'm not sure what the next 720hr will be like and that is starting to worry me. So, patch and go for now.
 
  
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New pin and beat back into place. Had to grind and smooth things out before I painted. No cracks in weld or metal and that's what I was afraid of so that's good.Just waiting on my steel hydro line, which must be made of gold..
 
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New pin and beat back into place. Had to grind and smooth things out before I painted. No cracks in weld or metal and that's what I was afraid of so that's good.Just waiting on my steel hydro line, which must be made of gold..

Have the hydro pumps been tweaked?
 
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That has nothing to do with hydraulic pressure. If the system was set over spec or a relief valve stuck, it would pop a seal on a cylinder (the weakest one first). For kicks and grins, I set off the loader on the M9, no easy task, the big tractors and big loaders aren't easy to separate, and checked my pins with everything depressurized. My pins are pristine at 3000 hours on the loader. Some burnishing but thats it. But then my units are 10 years old so the steel I'm sure is different.

I thought abbout taking the loader off the 105 too, but I run a set of auxillary lines on the 105 that operate a hay accumulator so it's even more of a PITA.

Little CUTS and Sub Cuts are easy to pull loaders compared with the big units, but I wanted to look. No issues with mine.

Gave me a chance to clean out the old accumulated grease and ruin some old shop towels too.
 
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mike69440

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Tweeked? No they were both replaced at 70hr under warranty because they imploded. The relief valves are set to stock standards.

I have been runing my main Pump/ loader on my L39 for years at 2900 PSI, there abouts. Spec is 2770 PSI. Does not load the motor down much more than factory setting and Pumps are nice and quiet with 2000 hrs on the tractor. These pins, even weaked by a grease hole, should not be snapping.

I have not played with my BH pressures.
 
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I wasn't aware they had 2 pumps. I thought mine had one pump for everything but mine are gear drive / hydraulic shuttle units. Never had a reason to investigate because nothing breaks. My M series do hold a lot of fluid. A full change is 15 gallons. Needs a BIG change pan. I use a cut in half truck diesel fuel tank. Needs a big wallet too. Super UDT ain't cheap.
 
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That has nothing to do with hydraulic pressure. If the system was set over spec or a relief valve stuck, it would pop a seal on a cylinder (the weakest one first). For kicks and grins, I set off the loader on the M9, no easy task, the big tractors and big loaders aren't easy to separate, and checked my pins with everything depressurized. My pins are pristine at 3000 hours on the loader. Some burnishing but thats it. But then my units are 10 years old so the steel I'm sure is different.

I thought abbout taking the loader off the 105 too, but I run a set of auxillary lines on the 105 that operate a hay accumulator so it's even more of a PITA.

Little CUTS and Sub Cuts are easy to pull loaders compared with the big units, but I wanted to look. No issues with mine.

Gave me a chance to clean out the old accumulated grease and ruin some old shop towels too.
Do any of your pins have a cross drilling and groove in the center to distribute grease?
 
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rScotty

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View attachment 463448 not sure why pics are sideways, but if you click on them they expand straight.

So the left side bucket cylinder top pin broke about 2 months ago. Broke right in half at the grease port. No biggie, because half of it slid out a little and I caught it. Today, not so lucky. Didn't notice that the other one broke in half, and half must of dropped out and boom. The cylinder pulled loose from the half of pin as it contracted, busting the steel line that feeds the hose and bending ears on the boom...
(SNIP)
I'm wondering If this thing is better off for landowners instead of using it for a business. Its a great size and can really move dirt but...

Hershey, I've been looking at those pictures and at my own M59 and still don't haven't come up with any explanations that satisfy me.

For those that don't know me, I'm a welder and machinist as well as an mech. eng., and spent a lifetime designing equipment of all types. Still do a bit of it in retirement. And I have the same tractor. Mine is also a 2008 with similar hours. It hasn't been totally problem free but darn near. I also use mine reasonably hard and sure haven't had anything like the problems that Herseyfarm has had.

A couple of things bother me about these pins. Yes, I know from other conversations that Hersey beats his machines hard. We've talked about that before. But even so, there just isn't any easy way to get a shearing stress onto the center of that pin - especially when there's a locking bolt still in place that prevents the pin from sliding laterally.... And what with the decent geometry and bulky end support it is equally hard to see how the pin break could be deflection induced either. And the other bother is that you say this wasn't the first pin you've had break. Hmm....Have you checked all the other pins on the machine? Of course once that pin did break then things could progress just as you said - your sequence sounds reasonable to me - what with the outer half of the pin working it's way out and once that happens the off-center push bending the ear until the hose failed. But trying to see how to initially get enough stress on center of the pin to start the sequence is the problem I'm having.

It's sure sounding like it started as a pin material problem. And that's surprising because Japanese steel is generally right there with the world's best. I assume that the pins are hardened or plated at some point...could that be a clue? Of course there are ways to check where and roughly why a fracture starts. Doing that formally is likely to be more expensive than this relatively inexpensive repair, but any metallurgist and most mechanics who have a 50x microscope and a few chemicals can tell you a lot about a break like this.

For my part, I'm sure going to pull the pins on my M59 and see how they look before the season starts. And I'm going to talk with the guy that owns the local cylinder fab shop to see if I've missed considering something obvious.... then I'm going to sit down and do some more thinking.

I'll not condemn the M59 or it's loader design because of this, but will certainly check mine carefully.
Oh, I forgot to ask; do you use any other buckets or QA bucket attachements on your M59? Is there any missing info there?
Thanks,
rScotty
 
   #20  

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Hershey, I've been looking at those pictures and at my own M59 and still don't haven't come up with any explanations that satisfy me.

For those that don't know me, I'm a welder and machinist as well as an mech. eng., and spent a lifetime designing equipment of all types. Still do a bit of it in retirement. And I have the same tractor. Mine is also a 2008 with similar hours. It hasn't been totally problem free but darn near. I also use mine reasonably hard and sure haven't had anything like the problems that Herseyfarm has had.

A couple of things bother me about these pins. Yes, I know from other conversations that Hersey beats his machines hard. We've talked about that before. But even so, there just isn't any easy way to get a shearing stress onto the center of that pin - especially when there's a locking bolt still in place that prevents the pin from sliding laterally.... And what with the decent geometry and bulky end support it is equally hard to see how the pin break could be deflection induced either. And the other bother is that you say this wasn't the first pin you've had break. Hmm....Have you checked all the other pins on the machine? Of course once that pin did break then things could progress just as you said - your sequence sounds reasonable to me - what with the outer half of the pin working it's way out and once that happens the off-center push bending the ear until the hose failed. But trying to see how to initially get enough stress on center of the pin to start the sequence is the problem I'm having.

It's sure sounding like it started as a pin material problem. And that's surprising because Japanese steel is generally right there with the world's best. I assume that the pins are hardened or plated at some point...could that be a clue? Of course there are ways to check where and roughly why a fracture starts. Doing that formally is likely to be more expensive than this relatively inexpensive repair, but any metallurgist and most mechanics who have a 50x microscope and a few chemicals can tell you a lot about a break like this.

For my part, I'm sure going to pull the pins on my M59 and see how they look before the season starts. And I'm going to talk with the guy that owns the local cylinder fab shop to see if I've missed considering something obvious.... then I'm going to sit down and do some more thinking.

I'll not condemn the M59 or it's loader design because of this, but will certainly check mine carefully.
Oh, I forgot to ask; do you use any other buckets or QA bucket attachements on your M59? Is there any missing info there?
Thanks,
rScotty
Good development. I dont see where you factored in the design of the pin tho. For lubrication, I believe these are drilled down the diametral center - then cross drilled and grooved at their length center to favor even greasing. Do you see a stress riser? ... Now consider that the pin sees force reversal and is prevented from turning. This combination of design choices presents the absolute best case for the pin to fail by fatigue. ----- The fact that a collar surrounds the pin groove alleviates but does not eliminate. The design described is unsound.

,,,After breaking 3 such sabotaged pins on my 7520 I replaced all pins in the curl circuit with solid pins and put a grease fitting on the collar. The only grooved pins left are the 2 that pin the lift cyls to the arms. They dont see such large forces or reversals. I am watching them closely.
 
  
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Hersheyfarm

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As far as beating this machine goes, I don't ram or beat rock with this. I've never ran any attachments front or back. I do try to move the most material and can with the front. Dirt being the heaviest and the m59 struggles with heaping scoops. It's been dry and I was pushing manure and dirt and back dragging dirt where the cows stomp it during winter. That in itself is very hard on front as far as it vibrating and slapping back and forth on the pins. That's when this one broke. The other broke couple months ago. Both snapped right at the grease groove.
 
   #22  

mike69440

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Hershey, I've been looking at those pictures and at my own M59 and still don't haven't come up with any explanations that satisfy me.

For those that don't know me, I'm a welder and machinist as well as an mech. eng., and spent a lifetime designing equipment of all types. Still do a bit of it in retirement. And I have the same tractor. Mine is also a 2008 with similar hours. It hasn't been totally problem free but darn near. I also use mine reasonably hard and sure haven't had anything like the problems that Herseyfarm has had.

A couple of things bother me about these pins. Yes, I know from other conversations that Hersey beats his machines hard. We've talked about that before. But even so, there just isn't any easy way to get a shearing stress onto the center of that pin - especially when there's a locking bolt still in place that prevents the pin from sliding laterally.... And what with the decent geometry and bulky end support it is equally hard to see how the pin break could be deflection induced either. And the other bother is that you say this wasn't the first pin you've had break. Hmm....Have you checked all the other pins on the machine? Of course once that pin did break then things could progress just as you said - your sequence sounds reasonable to me - what with the outer half of the pin working it's way out and once that happens the off-center push bending the ear until the hose failed. But trying to see how to initially get enough stress on center of the pin to start the sequence is the problem I'm having.

It's sure sounding like it started as a pin material problem. And that's surprising because Japanese steel is generally right there with the world's best. I assume that the pins are hardened or plated at some point...could that be a clue? Of course there are ways to check where and roughly why a fracture starts. Doing that formally is likely to be more expensive than this relatively inexpensive repair, but any metallurgist and most mechanics who have a 50x microscope and a few chemicals can tell you a lot about a break like this.

For my part, I'm sure going to pull the pins on my M59 and see how they look before the season starts. And I'm going to talk with the guy that owns the local cylinder fab shop to see if I've missed considering something obvious.... then I'm going to sit down and do some more thinking.

I'll not condemn the M59 or it's loader design because of this, but will certainly check mine carefully.
Oh, I forgot to ask; do you use any other buckets or QA bucket attachements on your M59? Is there any missing info there?
Thanks,
rScotty

Rscotty

While some equipment pins are hardened or hardfaced, the Kubota pins are plain carbon steel. Cross holes drilled in pins however especially if the holes are not chamfered nicely are excellent stress risers. I'd chamfer all pin x-holes before reinstall.
 
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Rscotty

While some equipment pins are hardened or hardfaced, the Kubota pins are plain carbon steel. Cross holes drilled in pins however especially if the holes are not chamfered nicely are excellent stress risers. I'd chamfer all pin x-holes before reinstall.
This will not be enuf. Regardless of blending, as you suggest, the weak area will still be at the center and the cross drilled hole will still be there to further accentuate the weakness and will have sharp edges that you cant get to. Cracking will initiate at those edges. Even the orientation of the cross hole relative to loading direction, and depth of the center hole wrt the cross drilling point will affect. ... Theres lots of optimization do do and it would all help. The time to do that is if there were no design choice in the lube matter. Putting a grease zerk on the collar and using solid pins is a straightforward cure.
 
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Of course you could pay a visit to your local heat treater and have them normailzed. It's not expensive.
 
  
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Hersheyfarm

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well, all back together and ready for action. I did check my pressure and at idle I'm at 2600psi and 2800psi at 2500rpm's.
 
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rScotty

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This will not be enuf. Regardless of blending, as you suggest, the weak area will still be at the center and the cross drilled hole will still be there to further accentuate the weakness and will have sharp edges that you cant get to. Cracking will initiate at those edges. Even the orientation of the cross hole relative to loading direction, and depth of the center hole wrt the cross drilling point will affect. ... Theres lots of optimization do do and it would all help. The time to do that is if there were no design choice in the lube matter. Putting a grease zerk on the collar and using solid pins is a straightforward cure.

Well, I'll go with your idea about stress risers. It makes a good working hypothesis. Certainly I don't have a better idea and am just now beginning to look at some of the details of the design. I still think that a close look at the broken pins might tell why they failed. What did you see looking at the three pin failures on your 7520?

Frankly I never paid much attention to the pins on the loader and backhoe before. But after taking a closer look at my M59 this afternoon it looks as though all of the pins on the loader and backhoe are made using that same basic design. It'll be interesting to see what I find when I pull a couple of them.
rScotty.
 
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rScotty

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well, all back together and ready for action. I did check my pressure and at idle I'm at 2600psi and 2800psi at 2500rpm's.

Best to check the pins on the other end of each loader arm before calling it done.
good luck,
rScotty
 
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Well, I'll go with your idea about stress risers. It makes a good working hypothesis. Certainly I don't have a better idea and am just now beginning to look at some of the details of the design. I still think that a close look at the broken pins might tell why they failed. What did you see looking at the three pin failures on your 7520?

Frankly I never paid much attention to the pins on the loader and backhoe before. But after taking a closer look at my M59 this afternoon it looks as though all of the pins on the loader and backhoe are made using that same basic design. It'll be interesting to see what I find when I pull a couple of them.
rScotty.
Well, on checking I was wrong on the number. ... I have 4 broken pins at the groove and one still in one piece - altho I replaced 6. :confused2: Something is misplaced?

,,,,,,Anyway the pin that is still whole is cracked nearly all the way around the groove - how deeply i dont know. The crack goes thru the 1/2 cross drilling hole. All the pins at the implement end are now solid. The base ends of the curl and lift cylinders still have grooved pins. Id better check them. The tractor has ~ 1500 hrs; many of them hard loader time.
 
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rScotty

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Well, on checking I was wrong on the number. ... I have 4 broken pins at the groove and one still in one piece - altho I replaced 6. :confused2: Something is misplaced?

,,,,,,Anyway the pin that is still whole is cracked nearly all the way around the groove - how deeply i dont know. The crack goes thru the 1/2 cross drilling hole. All the pins at the implement end are now solid. The base ends of the curl and lift cylinders still have grooved pins. Id better check them. The tractor has ~ 1500 hrs; many of them hard loader time.

When you replaced the pins on the Mahindra what did you use? Did you lathe some up or find a size that worked? Have you compared the pins on the Mahindra with similar pins on your Kubotas?

Apologies in advance for pelting you with questions, but my curiosity is up now, and will probably stay that way until we know a lot more about the design and materials used in these pins. The problem with trying to figure out a fix is that pins could could look very similar and not even be close to being similar in performance and material.
rScotty
 
  
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Hersheyfarm

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Out of curiosity what would you expect these pins to be made out of? Like a 4140 or 4150, same as gun barrels? And I guess the chrome finish is like an acid treatment or nickel?
 
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I suspect Kubota pins are plain vanilla carbon steel with a zinc or cadmium plate, 1020 bar or 12L14 free machining.

I'd be surprised if they were a Chrome moly. This is Ag stuff, that is their mentality.

Now if I were designing (using FEA of course) my super tractor, I'd have oversized S7 tool steel pins, HT and tempered with a Laser applied Nickel cobalt ally facing riding in a Garlock GGB maintenance-free bearings shells with grease seals fed by an automatic grease system. Ta Da!
 
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When you replaced the pins on the Mahindra what did you use? Did you lathe some up or find a size that worked? Have you compared the pins on the Mahindra with similar pins on your Kubotas?

Apologies in advance for pelting you with questions, but my curiosity is up now, and will probably stay that way until we know a lot more about the design and materials used in these pins. The problem with trying to figure out a fix is that pins could could look very similar and not even be close to being similar in performance and material.
rScotty

Out of curiosity what would you expect these pins to be made out of? Like a 4140 or 4150, same as gun barrels? And I guess the chrome finish is like an acid treatment or nickel?
This specialness in the pin is all done for convenience in lubrication. To provide this convenience the pin is compromised in the worst possible way. 1st, to do this at all invites copying because every greaser likes it. There is demand even in the face of seemingly random failure. By physics the design is unsound. By physics also, refinements can be incorporated to alleviate the unsoundness. However the fundamental modification is inherently bad and its unsound nature cannot be eliminated. So, since we have the motive to "copy" we open the likelihood of bad copies. They all will last for awhile; add strength blending, material and post fabrication sophistication, and then pure beef and they last longer. One may even think the problem is overcome. ... Well maybe - but at extreme comparative cost to simply using a solid pin.

,,,,Or maybe, right at the point the problem is "overcome" an antiwear plating is added. These are harder and more brittle than the pin. That stress riser still lurks inherent in the design. The parent metal by virtue of the augmenting refinements has been doing ok. Now tho it has a hard brittle plating which cracks and serves to start a crack in the parent metal. Hersheyfarm - IF your chrome or nickel plating extends across the groove it is a contributor to the failure. - After all this work to make inherently sabotaged pins function. - As you know, the true cost of your pin failure is huge compared to the still faulty replacement pin.

,,,,rScotty Yes, I have compared. ... The L2550 uses 1" pins, some of them drilled. They may or may not be grooved. The L3450 has a WOODS loader. It uses 1.25" solid pins. Huge in context.

-- The Mahindra, a monster by comparison, uses 1.125" Gr5 bolt blanks for pins - some drilled and grooved. This represents one example of a bad copy. ... The fact that 1-1/8 solid is plenty strong does not extrapolate to success on an equal pin having just a tiny bit of metal removed at the most strategic sabotage point. I used the undrilled variety supplied by the mfg for other loader pivots to replace all the drilled pins on the SK carrier. I would like to have gone to a larger pin to increase bearing surface as well, but that is a lot more difficult. They too would have to be solid.

Bolt blanks tend to be expensive so Iv bought some loong 1-1/8 Gr8 bolts so I can use the shank if any more of the drilled pins fail. The long gr8 are cheaper than the replacement gr5 pins from Mahindra.
 
   #33  

mike69440

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You really can fault Kubota for using mild steel in the pins, be it would be nice if it were normalized.
See, Mild steel bends, alot, before it breaks.
X drilled holes in mild steel have less stress concentration factor, are cheap to make, yada yada.
The simple fix is use the bigger pin and more bearing area.
and X holes and drilled thru at the ends are nice, given, but don not help the pins stay a single piece.
 
   #34  

mike69440

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You really can fault Kubota for using mild steel in the pins, be it would be nice if it were normalized.
See, Mild steel bends, alot, before it breaks.
X drilled holes in mild steel have less stress concentration factor, are cheap to make, yada yada.
The simple fix is use the bigger pin and more bearing area.
and X holes and drilled thru at the ends are nice, given, but don not help the pins stay a single piece
 
   #35  

mike69440

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You really can fault Kubota for using mild steel in the pins, be it would be nice if it were normalized.
See, Mild steel bends, alot, before it breaks.
X drilled holes in mild steel have less stress concentration factor, are cheap to make, yada yada.
The simple fix is use the bigger pin and more bearing area.
and X holes and drilled thru at the ends are nice, given, but don not help the pins stay a single piece
 
   #36  

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You really can fault Kubota for using mild steel in the pins, be it would be nice if it were normalized.
See, Mild steel bends, alot, before it breaks.
X drilled holes in mild steel have less stress concentration factor, are cheap to make, yada yada.
The simple fix is use the bigger pin and more bearing area.
and X holes and drilled thru at the ends are nice, given, but don not help the pins stay a single piece
Triple yes. ... It would be interesting to design a reasonable sized drilled and grooved pin for an application that HAD to use that greasing method. I have some ideas that would not add [much] cost. The big question is whether the sensitization of the area can be handled enuf so the pin can wear out rather than break. :eek:

....Its not like the center is too weak. Its the leverage of the rest of the bowing pin on a concentrated slightly reduced area. Fatigue.
 
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One, they are zinc irridite plated and two, the simple answer is to make replacements from certified Grade 5 capscrews (not Chi-com grade 5, domestic grade 5). If you use a Grade 5 capscrew, it's already heat treated and normalized.

You don't want a Grade 8. You want a Grade 5 or an A-325 because you need the elongation prior to fracture. Grade 8 will shear, a Grade 5 will elongate.

Simple matter to lop the hex head off the proper diameter shank and install, putting alemite fittings in the cross tubes instead of drilling and cross drilling the pins themselves.

Never had an issue with mine in 10 years.
 
   #38  

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Not to happy with Kubota pricing right now, see Posts #15 & 16
http://www.tractorbynet.com/forums/...m59-front-drive-shaft-leak-2.html#post4420381

Kubota should spend a little less on advertising and take care of your problem

This is a design miscalculation of possible loads on the pin or a materials defect. The repair should be on Kubota's nickel. The engineer(s) who designed this disaster should hand carry the repair parts to you.

PS this is not Photo-Shopped

Not sure what you are trying to show with your picture? If it's the fact that you are lifting the tractor off the ground with your backhoe I hate to tell you but I can easily lift my 580k off the ground of I bet the bucket under a solid root or rock. I have to be careful because if it suddenly lets loose it will slam back down on the ground. I tried to fill the bucket with dirt but all I did was peal apart the backhoe bucket like a pull tab on an old beer can. $350 for a used replacement bucket was all I needed to learn to live within the limits of the machine.

I think you'll find that Kubota uses mild steel simply because they want the pin to wear since it's the easiest part to replace. I replacing the right pin when the left pin would probably been a good idea. I think I would remove all the loader pins and inspect each one closely.
 
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Not sure what you are trying to show with your picture? If it's the fact that you are lifting the tractor off the ground with your backhoe I hate to tell you but I can easily lift my 580k off the ground of I bet the bucket under a solid root or rock. I have to be careful because if it suddenly lets loose it will slam back down on the ground. I tried to fill the bucket with dirt but all I did was peal apart the backhoe bucket like a pull tab on an old beer can. $350 for a used replacement bucket was all I needed to learn to live within the limits of the machine.

I think you'll find that Kubota uses mild steel simply because they want the pin to wear since it's the easiest part to replace. I replacing the right pin when the left pin would probably been a good idea. I think I would remove all the loader pins and inspect each one closely.

I ignored that post and chalked that one up to 'stupid is as stupid does'.:D
 
   #40  

SPYDERLK

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One, they are zinc irridite plated and two, the simple answer is to make replacements from certified Grade 5 capscrews (not Chi-com grade 5, domestic grade 5). If you use a Grade 5 capscrew, it's already heat treated and normalized.

You don't want a Grade 8. You want a Grade 5 or an A-325 because you need the elongation prior to fracture. Grade 8 will shear, a Grade 5 will elongate.

Simple matter to lop the hex head off the proper diameter shank and install, putting alemite fittings in the cross tubes instead of drilling and cross drilling the pins themselves.

Never had an issue with mine in 10 years.
'

I think you'll find that Kubota uses mild steel simply because they want the pin to wear since it's the easiest part to replace. I replacing the right pin when the left pin would probably been a good idea. I think I would remove all the loader pins and inspect each one closely.

Whoa! ... Perhaps we need a little background on material. - All material, steel included, acts like a spring until it doesnt. That is to say it flexes when it is loaded. The more load the more flex. But until the flex exceeds the elastic limit of the material the piece will return to its original shape after the load is released. If instead load continues to increase you finally reach a point that the metal "gives" [yields plasticly] and begins to bend. You never want to reach this point in a loader pin because they see repeated load reversals in their use and will bend back and forth.

A stronger pin is a better spring. A pin of the same size has almost exactly the same stiffness as the weaker steel; flexing the same per given load. It is stronger because at the point the weak pin is damaged [bends] the strong pin is still just flexing. ... So you want the pin made of the stronger steel if ample sized pins arent used. The stronger metal is undamaged by the load and will last. ... Talking equal size; a Gr5 will last where a grade 3 wont, and a Gr8 will last where the Gr5 wont. But, since theres no difference in the stiffness theyll all act the same in the assembly seeing the Gr3 load.

All pins bow in response to load. Thats the problem with using a small pinned assembly and upgrading to a strong alloy pin to make it survive. The strong alloy "makes" its strength by being able to withstand higher deflection without bending. The strong alloy bows back and forth - itself happily enuf, but slowly wallowing out the ends of the crosstube bore because of the intense forces out near the shear point. The strong solid pin happily accommodates the bellmouth by bowing a little further. The ones that are grooved at the center start to die. That bowing is concentrated there by the full cross section on each side, finally exceeding the elastic limit of the surface metal in the groove. It cracks at the groove - a cross hole accentuates the start of cracking. With equal loading the Gr8 would have gone a little longer due to its higher elastic limit but as the bellmouth worsened ... you get the idea.

Since stiffness goes as the cube of thickness [in this case diameter roughly], big pins are the answer - absolutely if drilled and grooved. There is no point paying for high strength steel because bowing is so miniscule as to pose no fatigue threat. The pivot remains happy thru a long life.
,,, If a maker goes the small strong pin route to support high load theyd better use solid pins. Still the relatively great bowing under high load will wear/deform the joint much faster.
 
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But the unknown factor is what will cause the pin or any pin to fatigue and shear eventually and that is... How much clearance there is between the outer bosses on the loader frame and the pivoting point on the loader that the pin fits through. That is the 64 dollar question, shall; we say....

If the pivoting part of the loader that the pin fits through is small in length to the point of being excessive, failure will occur and thats what none of us actually know. I do know on my big Kubota's the boss to pivot fabrication spacing is minimal, about 3/32" on each side. Excessive spacing will cause failure every time.

BTW, a Grade 5 will yield (plasticize) more in respect to elongation that a Grade 8. I happen to be in the alloy steel business, thought in flat rolled high strength not fastneres but a quick look at the ASTM specification will bear that out.
 
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BTW, a Grade 5 will yield (plasticize) more in respect to elongation that a Grade 8. I happen to be in the alloy steel business, thought in flat rolled high strength not fastneres but a quick look at the ASTM specification will bear that out.
Yes. That would be expected. The Gr8 supports larger elastic deformation tho before it goes plastic/suffers damage. Particularly with forward and reverse loadings you dont want to go too near the yield point. Altho the metal will strengthen at early yield, that robust response is only a benefit if loading is only one direction . ... The response does not tolerate reversal well.
 
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Which begs to ask just how much clearance there is between the loader frame ears and the moveable portion of the upper arm and or the weldment. Without pulling my loader again (no small feat on my large frame Kubota, I see to remember that the upper arm (a fabricated weldment) has a heavy walled tube welded into it. If the tube is too short (which creates excess space between the uprights and itself, that imparts what I would assume a failure load on the pin.

Something to ponder and keep in mind if I remember correctly this isn't the first time so I wonder if, when he pounded to uprights back, he didn't aggrivate the condition by increasing that gap. Wouldn't take much. There is a lot of strain in that area. I know my big loader is heavily gusseted in the upright area.
 
  
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i had a peice of 3" sqruare channel that I cut to the same measurement as the other side and used it as a spacer. 2 5/8" if I remember. As far as lateral movement, the is a lot of side movement on the loader. Like a 1/2". Let the pressure off and you can move cylinders back and forth.
 

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Oh, & Hearsheyfarm, I really like your attitude! You realize that you have a few years & hours on the machine, also don't abuse the machine, but get "every nickel" out of it you can, (like we all do). You wish that some things were a little "beefier" from the factory, but when you have troubles, you just take care of it without coming here crying. :thumbsup:
This sounds like another accoutant vs. design engineer conflict that is just a fact of life good or bad.
 

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'



Whoa! ... Perhaps we need a little background on material. - All material, steel included, acts like a spring until it doesnt. That is to say it flexes when it is loaded. The more load the more flex. But until the flex exceeds the elastic limit of the material the piece will return to its original shape after the load is released. If instead load continues to increase you finally reach a point that the metal "gives" [yields plasticly] and begins to bend. You never want to reach this point in a loader pin because they see repeated load reversals in their use and will bend back and forth.

A stronger pin is a better spring. A pin of the same size has almost exactly the same stiffness as the weaker steel; flexing the same per given load. It is stronger because at the point the weak pin is damaged [bends] the strong pin is still just flexing. ... So you want the pin made of the stronger steel if ample sized pins arent used. The stronger metal is undamaged by the load and will last. ... Talking equal size; a Gr5 will last where a grade 3 wont, and a Gr8 will last where the Gr5 wont. But, since theres no difference in the stiffness theyll all act the same in the assembly seeing the Gr3 load.

All pins bow in response to load. Thats the problem with using a small pinned assembly and upgrading to a strong alloy pin to make it survive. The strong alloy "makes" its strength by being able to withstand higher deflection without bending. The strong alloy bows back and forth - itself happily enuf, but slowly wallowing out the ends of the crosstube bore because of the intense forces out near the shear point. The strong solid pin happily accommodates the bellmouth by bowing a little further. The ones that are grooved at the center start to die. That bowing is concentrated there by the full cross section on each side, finally exceeding the elastic limit of the surface metal in the groove. It cracks at the groove - a cross hole accentuates the start of cracking. With equal loading the Gr8 would have gone a little longer due to its higher elastic limit but as the bellmouth worsened ... you get the idea.

Since stiffness goes as the cube of thickness [in this case diameter roughly], big pins are the answer - absolutely if drilled and grooved. There is no point paying for high strength steel because bowing is so miniscule as to pose no fatigue threat. The pivot remains happy thru a long life.
,,, If a maker goes the small strong pin route to support high load theyd better use solid pins. Still the relatively great bowing under high load will wear/deform the joint much faster.

What an excellent explanation, Spyderlk! The physics is sound, not only does your theory fit all the facts that we know about from Hersheyfarm's descrition of the failure, it even puts the forces and their effects into the right locations. I couldn't just leave such a good explanation to be read once, but had to quote it again.

That's an especially nifty idea about the concentrated forces "wallowing out the ends of the crosstube bore. I suppose the same applies to the loader frame ears? Anyway, it was a nice touch taking the idea of that wallowing and allowed it to cause increased bowing of the pin until yield leads to fatigue....a failure that would be concentrated exactly at the cross section where we know that Hersheyfarm's original break happened.

For me, it was when you includ the wallowing that helped me to picture the failure. Before you introduced that idea, I just couldn't square the physics and the failure.

Yes, we have to remember that in the beginning, Everything Flexes.....Nicely done.
In fact, this whole discussion about "how materials work" reminds me of the best of those engineering textbooks. Exciting stuff - both then and now.
Thanks again. From now on I'll be looking at loader pivot construction in a whole new light.
Enjoy,
rScotty
 

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i had a peice of 3" sqruare channel that I cut to the same measurement as the other side and used it as a spacer. 2 5/8" if I remember. As far as lateral movement, the is a lot of side movement on the loader. Like a 1/2". Let the pressure off and you can move cylinders back and forth.
,,,,,,,:eek: ,,,Now it comes clear. That is a huge gap for the pin to cross unsupported. Kub has made a mistake - more encompassing than I thot. Have you spoken to a service rep? Corporate is not going to notice a trickle of issues unless you reach higher up the chain and explain it to them. While solely using a solid pin would work, the assembly is self abusive. - The boss across the end of cyl needs to be widened.
 

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,,,,,,,:eek: ,,,Now it comes clear. That is a huge gap for the pin to cross unsupported. Kub has made a mistake - more encompassing than I thot. Have you spoken to a service rep? Corporate is not going to notice a trickle of issues unless you reach higher up the chain and explain it to them. The boss across the end of cyl needs to be widened.

Not sure it's a mistake pr if the guy cutting the blanks on the horizontal bandsaw didn't cut some too short (misreading the print) and they went into production units and weren't caught before being fitted. I surmised from the outset that the welded in tube was too short.

Reason I say some is it's not a widespread issue, in fact, so far it's just this one loader. People make mistakes all the time, thats human, but it should have been checked and rejected and it wasn't (by QC).

Finally, did Kubota build the loader at all or did Woods? I was under the impression that Woods built or has built some Kubby loaders.

Things to ponder, also things to address with Kubota in Torrance, California.
 

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Not sure it's a mistake pr if the guy cutting the blanks on the horizontal bandsaw didn't cut some too short (misreading the print) and they went into production units and weren't caught before being fitted. I surmised from the outset that the welded in tube was too short.

Reason I say some is it's not a widespread issue, in fact, so far it's just this one loader. People make mistakes all the time, thats human, but it should have been checked and rejected and it wasn't (by QC).

Finally, did Kubota build the loader at all or did Woods? I was under the impression that Woods built or has built some Kubby loaders.

Things to ponder, also things to address with Kubota in Torrance, California.

What an interesting thread. I went out and took a look at my M59 this morning. I expected to see something like your speculations....something familiar to a US design mind. Something hopefully better made than an add-on Wood's loader because those are add-on's for farm tractors and this loader was deliberately designed as Kubota's entry into the the construction machine market. So they would be expected to assume that the loader would see somewhat higher stresses and lots more repetitions.

Looking at our M59, I can see that these upper loader arm pivots are NOT "welded on tubes"...nor is the piece a "blank cut on a horizontal bandaw". Arm pivots made like that would be appropriate for a lower stressed farm loader. But here we have a cast and machine-bored end piece that is welded (nicely) onto the end of the arm. It even has a boss especially cast as a place to drill and tap for a zerk. The problem - other than the unused zerk boss being in the wrong place - is that the cast piece is only 2.75" wide whereas the loader frame mounting space is 3.75" wide there. Why? The cast piece could easily have been wider....there's sure room for it. As it is, the cast pivot piece they've welded on is narrower than the arms themselves. All in all, that cast piece looks suspicioulsly like it was borrowed from a smaller loader - right down to the unused zerk boss.

Here's a couple of photos:
 

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