What were the engineers thinking?

TheOldHokie

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Went to grease the LA525 loader today and discovered the retaining cap screws in both lower bucket pins were MIA. This has all of the hallmarks of a chronic issue. The ends of the screws stick out on the bottom side just begging for the nut to be caught and snapped off when grading with the bucket, snow plow, grapple, etc. Contemplating possible fixes for what looks to be a poor design - e.g. using roll pins or threading the cross drilled hole in the pivot pins and using shorter cap screws. Appreciate any thoughts or relevant experiences.

Dan
 

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Chanceywd

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You have my attention, I was doing some grading and back dragging the last 2 days, Guess I better check mine.
 

Roadworthy

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Thanks for the post. I'll check mine later today. It does appear to be a design flaw or oversight.
 

Tughill Tom

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Went to grease the LA525 loader today and discovered the retaining cap screws in both lower bucket pins were MIA. This has all of the hallmarks of a chronic issue. The ends of the screws stick out on the bottom side just begging for the nut to be caught and snapped off when grading with the bucket, snow plow, grapple, etc. Contemplating possible fixes for what looks to be a poor design - e.g. using roll pins or threading the cross drilled hole in the pivot pins and using shorter cap screws. Appreciate any thoughts or relevant experiences.

Dan
Look at using Button Head bolts and the lock nuts on the top side.
 
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DustyRusty

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When I purchased my tractor, all the retaining bolts were loose, and the nuts not tightened completely. The dealer told me that is how the tractors are supposed to be assembled, and I am certain that the engineers at Kubota have a good reason for it being done that way.
 
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TheOldHokie

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When I purchased my tractor, all the retaining bolts were loose, and the nuts not tightened completely. The dealer told me that is how the tractors are supposed to be assembled, and I am certain that the engineers at Kubota have a good reason for it being done that way.
The engineers intent is quite clear. But I would have asked the dealer why that was the intent along with why the engineers thought the loose or otherwise 1/4" fasteners were going to survive when dragged laterally through dirt, rocks, stumps, and along pavement by a 4000 pound 40HP tractor. They are on the bottom surface of the loader arms in a very vulnerable location and stick out like a sore thumb. It is quite obvious they won't survive long in the work I do. These two didn't last 40 hours. and I am sure I can put some longer ones in just like the first two and duplicate the failures with minimal effort.

Dan
 
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TheOldHokie

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engineers only design, few seldom, if ever USE what they design in the REAL world....
I have a 40 year professional career working with engineers of just about all flavors and I don't believe that characterization for a moment. But engineers are human and like all humans they sometimes over think things and make poor decisions. Unless someone can articulate a rational engineering explanation for this design I am going to put it in the poor decision file drawer.

Dan
 
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B737

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They changed the design of those pins on 535. I wonder if you could retrofit. It uses a flange that is bolted to loader that retains the pin.
 

Goz63

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Check your zerk fittings as well. Found one of mine missing at the bottom of my bucket. Dealer came out and replaced it and check the others ones. He found them all loose on the FEl. He tightened all of them. It’s the little things sometimes.
 

Lil Foot

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How about drilling a new cross hole 90 degrees from the original?
Retaining screws would be a little more removed from the "action".
 

TheOldHokie

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How about drilling a new cross hole 90 degrees from the original?
Retaining screws would be a little more removed from the "action".
That would definitely be an improvement. I was also considering making new pins with a small raised annulus on the zerk end and a HD snap ring groove on the other end. Very easy to make and would seem to satisfy the original design requirements.

Dan
 

SDT

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I have a 40 year professional career working with engineers of just about all flavors and I don't believe that characterization for a moment. But engineers are human and like all humans they sometimes over think things and make poor decisions. Unless someone can articulate a rational engineering explanation for this design I am going to put it in the poor decision file drawer.

Dan
A design engineer for many years in one of my former lives, I agree.

SDT
 

GreensvilleJay

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Well I've got 5+ decades in the design/build field and frankly seeing how 'things are built' today really shocks me. Have a good friend ,who was part of the team on the Canadarm project. He quit after being told 'that's not needed'.....from the senior engineers. Well,long story short, 6 months after he left, 'they' decided his way was CORRECT. Have had similar reports from friend at Litton,SPAR and a few other places. While at STELCO, had a senior eng tell me 'No, that's not right..has to be done THIS way'. Well his EGO cost the company about a million Canucks and he never,ever admitted that I was right.
The big problem I see is them relying on 'computer simulations', which frankly don't simulate the Real World' of hot.cold, vibrations, dirt,salt,etc. and very few actually use/operate what they design.
 
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TheOldHokie

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Well I've got 5+ decades in the design/build field and frankly seeing how 'things are built' today really shocks me. Have a good friend ,who was part of the team on the Canadarm project. He quit after being told 'that's not needed'.....from the senior engineers. Well,long story short, 6 months after he left, 'they' decided his way was CORRECT. Have had similar reports from friend at Litton,SPAR and a few other places. While at STELCO, had a senior eng tell me 'No, that's not right..has to be done THIS way'. Well his EGO cost the company about a million Canucks and he never,ever admitted that I was right.
The big problem I see is them relying on 'computer simulations', which frankly don't simulate the Real World' of hot.cold, vibrations, dirt,salt,etc. and very few actually use/operate what they design.
Judging by your choice of words I am guessing you are not an engineer.

Your chouce of physical phenomena is also an interesting coincidence. I actually spent the first twenty years of my professional career as a mathematicisn and software engineer at a Navy research lab were much of what I and my fellow researchers did was develop mathematical models and computer simulations for the effects of heat, salt, corrosion. vibration, noise. etc. Today those mathematical abstractions have a well earned reputation for reliabilty and accuracy proven by decades of real sea trials and operational testing. They have shortened the ship design cycle by an order of magnitude or more and you have fleets of warships that rely on the accuracy of that data for their very survival.

Dan
 
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Lil Foot

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It is like everything else- engineers vary greatly.
I have had the privilege of working with some of the finest engineers/scientists on the planet, and I have worked with some that could not engineer their way out of a wet paper bag without lots of help.

An example of one that we lovingly called Mr Potato Head; he always insisted that all tap drill holes be held to +.0002 dia., while their location was routinely called out to +/- .005, or not dimensioned at all.
He insisted that our metrology lab check the holes before they were tapped. Nothing could alter his belief that this was necessary, and he was finally removed from all design work by our boss in order to save time & money.
 

lugbolt

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The whole purpose of manufacturing is to sell a product that competes with other brands in quality, styling, etc., a product that has reasonable reliability, meets government standards and regulations, yet still turn some sort of profit. There is a lot more to it, but that's the very basic idea.

And therein lies many issues for engineering.

Remember they still have to turn a profit. Meaning if a JD of the same size is $5 less expensive, they're gonna cut $7-$10 out somewhere, maybe getting a bolt cheaper from a different supplier or whatever.

So on a loader pin you have a lot of options. The way the 525's are designed is the same as they've been for decades. Bolt through the end of the pin, and it hasn't really been an issue to my knowledge. If it was, it was minor enough for owners to just toss another bolt in. Excavators have roll pins in the bucket pivot and those roll pins are a pain in the backside!! Ideally you need a roll pin punch to remove them, and when removing they are usually junk--IF you can get them out at all. I burned many of them out, and replaced the pins-on brand new equipment (bucket swap, QA install or Thumb install). The flanged bolts are also a thorn in my side because folks bust the head of the bolt off on rocks/dirt/whatever and then I got the joys of drilling a bent bolt out of a hole. Some of them were through-bolted with a nut on back and those were easy as long as the pin's flange wasn't bent up, even then just replace it. But therein lies the issue. Customer gripe about the cost of a pin + labor + bolting it back on. B7100 loaders and some of the smaller B series years ago had nothing but COTTER PINS holding loader pins in. Some mad customers over there, but ya know what? It cost the dealer MORE money to assemble those than it does a LA525. We had to put the pin through, line the hole up, then stuff a cotter pin into the hole, and fight with it to bend the legs of the cotter pin sufficiently. It cost Kubota more in warranty claims because the dealer setup techs would oftentimes get in a hurry (Imagine that) and wouldn't bend the legs far enough, pin came out, bent the cheap loader frame or whatever. So they changed to through-bolts like the 525's are designed with now. They are inexpensive, and fewer problems with them. On the cotter pins some of them you could NOT get to them, the hood was in the way, all kinds of stuff-you couldn't get any dikes in there to bend the legs. And you ain't bending the legs over on a 1/4" cotter pin by hand.

No matter how it's designed people are going to gripe about it, and Kubota's engineers know this. Thus, the least expensive way to retain the pins on the standard L series that is an acceptable method as far as reasonable reliability is to through-bolt them. And no the bolts do not get fully tightened. You run the nut down until there is approx 1/4" of play and you're done. This is to allow the bolt to float in the pin so it'll come out later. Also, it allows the pin to float just a little bit which keeps the pin from seizing into the loader frame and/or bucket (or cylinder). Some of the M series have a boom pin that is flanged and bolted, and almost all of the ones I've done were seized completely because there is no play, no way for the pin to keep itself from rusting/seizing into the bore. Common for those to just shear the flange off, and on the ones that had a welded pin and a snap, those were even more common to seize and shear. So the sensible solution? Grease them!! Well guess what, it's inconvenient for people to take 5 minutes out of their "maintenance" schedule to put a grease gun on things, that is if they even know it has a fitting. So many times, I've replaced entire engines, transmissions, pins, blades, you name it--because the owners don't even know "they're supposed to check that". I had mentioned this to an older gentleman who grew up working on 8N Ford's and 850's, etc and he said it's nothing new, but there's more of it now because there are more people now. Fair enough. I guess.

and yes I know of at least one of the engineers at Kubota USA (Georgia) and that person does in fact own and use a Kubota. This person and I spoke a while back, I will call him Kevin. I told Kevin that I think some things on the equipment could have been better designed, and he agreed--however if we designed them to meet everyone's needs, it would weigh 100,000 lbs, it would be larger than an 18 wheeler, ugly as sin, and would cost $250,000. But it would be easier to work on. As he said, you can't please everyone but they don't stop trying.
 
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