ARRRRRRGH!!!!!!! Broke my tractor.... Engine Block went SNAP...

[TomOfTarsus]

Don't forget that weighted tires don't contribute to the bending that would have caused this crack.

& yes, the bean counters are alive and well and have caused more than one product to have a little too much safety factor cut out. From what y'all are saying about similar tractors on TBN not having this problem, Kris appears to be one of those on the toe of the Bell curve. Sad, aggravating, and expensive.

I hate to see Kris's pockets emptied when it appears that is not his fault.

Realize that the lack of similar experience from other members on this forum with similar equipment and operating practice can only mean two things:

(1) Kris was abusing his equipment (not likely from all that's been said here)
(2) Kris's equipment was defective or designed too close to the edge

The comment about cold vs. hot caught my attention - it doesn't take a rocket scientist to know that the cold side of the casting is in tension, and any defect or inclusion in the casting is just like the stone pit in your car's windshield - get overzealous with the defrosters, heat up the inside of the glass and likely a crack will run.

I've done more than one failure analysis where we showed that the nominal design was indeed safe, but that within the bounds of normal manufacturing practice for those parts, failures were impossible to guard against.

I recall one major manufacturer of large electrical motors saying they heartily disagreed with our conclusions - and then quietly adopting our recommended fix!

I'm concerned about this whole thing as well because my itty-bitty 1999 TC-18 with the 7160 loader looks like it may be susceptible to the same problem. DDW (dear, disgusted wife) would not be happy!

Hope this helps.

 

[dynasim]

I could not afford a tractor that had a zero probabibilty of failure.

No amount of additional metal will correct for a casting flaw in a high stress location.

Anybody who thinks that those design decisions are easy, straightforward, and obvious would not be welcome anywhere near anything that I had a responsibilty for designing.

Saying that the tractor designers made poor choices on the basis of this one incident is not grown-up conversation.

Perhaps if they had just made the sheet aluminum on the Comet(the first Jet airliner) twice as thick, and they cut out have of it passenger capacity, the Comets would not have broken in half and crashed, and the British Jet Aircraft business would have prospered. However, we know that that would not have helped one little bit(It was an unobvious window design feature).

Kris should be applauded for bringing this to our attention for discussion. However, the additional wild, unsubstantiated, company/designer/engineer/tractor/loader bashing isn't helpful. If this was a casting flaw, NH ought to fix it.

I have not heard one reply that has provided any indication other than this is a very rare problem. If I am wrong, please educate me.

Chris

There is my rant/engineer defense for the day.

 

[Eagleview]

http://www.tractorbynet.com/forums/kioti-owning-operating/116184-friends-ck25-broke-two.html I don't know what all the talk of "bad luck" and it's the first time it's been mentioned on the forum , theres been two tractors break in as many weeks . Everyones had their own ideas to what has happened but it happens . Im now wondering how often it happens and goes unreported . As far as im concerned you should'nt be able to break a tractor with normal use . They are work horses and should not be able to hurt themselves with their own power . If you broke it pulling logs out of the scrub with both front wheels off the ground and steering with the brakes you would kick your own *** , but if it broke clearing a little snow id be looking for another *** to kick .

 

[crashz]

I'm shopping for a new tractor and have noticed that Kubotas new loader design on the L series is attached to the tractor by mearly a tube that attaches to the bell housing. No front or rear support.

But on second thought, the carbon steel tube may act as a torsion bar and help to absorb shock loads and isolate them from the castings. So the defelction caused by hitting an object with the bucket will be absorbed by materials with a natural elasticity.

 

[TomOfTarsus]

Chris (dynasim):

Sorry if I appeared to be bashing engineers. Seeing that I am one, that'd be kinda self-deprecating in a non-funny way. And I also know from experince that all good design involves tough decisions. But I also know that failures are out there, and have investigated a few where insufficient allowances were made for normal manufacturing variations. That doesn't make the engineer a scumball, just human. Heaven knows when I started in this business I didn't think my fragile self esteem would survive my boss's scathing assesments of some of my analyses, many of which were summarized by a one-word analogy to a substance we often encounter in the cow pasture!

I agree that no one could afford anything if it had a zero probability of failure. As I noted, Kris is probably out on the toe of the curve somewhere. I'm sure you recall those reliability factors & all the rest of the K's that go into a fatigue strength calculation. Criminee, maybe he had it good and hot and a load of snow fell off a pine bough and hit that cast cover - he didn't say anything like that, but maybe he never saw it. There is also the other crack on the bolt dog, which appears to be old - I don't know how that one is situated relative to the failure.

I was simply speaking from my own experience and raising the possibility. I don't think my post was wild and unsubstantiated. It simply stated the possibilities. As well, I was exercising a technique taught to me be a dear mentor, a much more accomplished engineer than myself - that lack of failure cases can say something, too.

Further, we have to look past the design itself - I've seen failures caused by one shift doing something different from the next shift; by misread or misapplied inspection techniques - we're all human, we all have bad days, we all make mistakes. For instance, IF the cracked bolt was was in a place that weakened the tractor and contributed to the failure, was it caused by the bolt being improperly torqued in the first place? And even that may not be a worker's direct fault - some unseen debris or internal thread corrosion, malformed threads, a defective torquing device - stuff happens, and we just have to try to learn from what we discover and try to eliminate the possibility by changes to the procedure, inspection techniques, etc.

But now it appears we have a second cracked tractor (thanks, Iron Horse). Shall we go have a virtual look? Let's help our fellows out and get at the facts, if we can.

Best Regards,

Tom

 

[MikePA]

I could not afford a tractor that had a zero probabibilty of failure...

I agree with everything you wrote.

The fact a Kioti also broke (after abusive backhoe use - lifting the front end off the ground, then bouncing down several times) is irrelevant to a NH tractor breaking.

Anyone who's been on any discussion forum for more than 5 minutes knows people are much more likely to post about problems. If this were a design problem, then there'd be more reports of this. The Class II Boomers have been around at least 6 years and the first few years only came with the 7308. That's a lot of years and hundreds, if not thousands, of hours of combined FEL use and this happened to 1 person, i.e., an anomaly, albeit a painful anomaly to Kris. As an anomaly, you look for what's unique about a situation, not jump to conclusions about an entire population of tractors, across manufacturers no less.

Then put yourself into the servicing dealer's position. You've probably never seen something like this. Never had a Class II come in with a cracked block. Never. Maybe never even seen a CUT with a cracked block. What do you think is going to be the first possible cause you're going to think of? It's not going to be, "NH has a design problem."

 

[TomOfTarsus]

So with the Kioti fracture as a result of abuse, it comes back to what was suspect all along: an anomoly. Lots of votes going in that column. I also agree, if it's a casting defect, then NH should stand behind it.

 

[mrutkaus]

Sorry. "No good deed goes unpunished."

Mike

 

[plastikosmd]

does this loader tie to the front of the tractor? i tried using the NH site, but it is slow as heck with pictures taken from 2 miles away, couldnt tell. one of the reasons i went with my 300cx on my JD machine over the others i was looking at, at the time was the fact the loader arm uprights are tied to the to the front of the frame to provide a strut when lifting, preventing arm rotation and also when slamming into something, it goes into tension, again preventing rotation/unloading the other way. yet still quick attach. lot of the other quick attaches i looked at got away from a front component, probably a design issue. heck a lot of distance between the attachment of the loader to the tractor and the weight it is lifting, large moment, so that attachment has to be beefy!

 

[Eagleview]

I agree with everything you wrote.

The fact a Kioti also broke (after abusive backhoe use - lifting the front end off the ground, then bouncing down several times) is irrelevant to a NH tractor breaking.

Anyone who's been on any discussion forum for more than 5 minutes knows people are much more likely to post about problems. If this were a design problem, then there'd be more reports of this. The Class II Boomers have been around at least 6 years and the first few years only came with the 7308. That's a lot of years and hundreds, if not thousands, of hours of combined FEL use and this happened to 1 person, i.e., an anomaly, albeit a painful anomaly to Kris. As an anomaly, you look for what's unique about a situation, not jump to conclusions about an entire population of tractors, across manufacturers no less.

Then put yourself into the servicing dealer's position. You've probably never seen something like this. Never had a Class II come in with a cracked block. Never. Maybe never even seen a CUT with a cracked block. What do you think is going to be the first possible cause you're going to think of? It's not going to be, "NH has a design problem."

Abusive bachoe use , were you there ? As for the rest , were talking about bad loader frame engineering . ANY loader frame thats built in such a bad fashion .