Backhoe BH77 broke - defective part?

[Texas Fella]

For the record, I have no pressure on me to lay fault anywhere. I get paid either way (customer or warranty). In fact, if it is a manufacturing defect, I am better off calling it that and finding the customer a fix for it. Do you think that just because I say "it's your fault" that I quite getting my a** chewed. If there is a repeat failure, it is my job to find the problem and get it fixed. Sometimes, that means telling the customer it is their fault, sometimes, it's letting the manufacture know that they have and issue. Either way, I get paid.

 

[Texas Fella]

I noticed the picture on the original post of the new BH (looks like it is from Kubota's literature). I bet that shifty looking guy in the back ground knows what is wrong with them and knows how to fix them.

 

[wdchyd]

I noticed the picture on the original post of the new BH (looks like it is from Kubota's literature). I bet that shifty looking guy in the back ground knows what is wrong with them and knows how to fix them.

:laughing::laughing:......Good one..!!

 

[SixHoeBob]

Really, demand your money back? What have we come to in this society when a major manufacturer can not make a mistake with out having to take back it's product. Do not get me wrong, Kubota should take care of these issues ASAP, and at no charge to the customer. You paid for a functioning product, and you should get one. However, there is no proof that it is an undersized pin. In fact, based on our information here on TBN, nothing is fir sure. If the manufacture screwed up, give them a chance to make it right. If we (as a society) keep up with this "walmart" mentallity of "something on it broke, I want my money back" then ALL corporations and small business will have to charge so much for their products that we will not be able to afford them. Just my 2 cents, take it or leave it.

I have read all of the posts in this thread so far and forgot most of them and who wrote them, so you might be asked to repeat yourself.

I like the term "Sand Box Engineering"

Sorry about my Wal-mart mentality, but I developed it while fighting with poorly engineered equipment that I paid dearly for.

Please try your hand at SBE, and tell the readers the answers to the following:

*Why did the pin break?

*How long will the new pin last, before it breaks?

*Who will compenstate the hoe owners for lost time and aggravation each time the pin breaks?

*Who pays for the hauling, parts, and labor?

*How much is the total repair bill for pin, boom, 2 cylinders, labor,etc? $3K?

*What design change will be needed to stop the pins from breaking?

*Any other relevant comments.

I can only afford used equipment, so I am stuck finding solutions at my expense. I think one of the reasons the OP bought a new hoe is so that he could use it without having to work on it - repeatedly.

There is another thread where the man received his JD back from the dealer and he is upset because they might be the ones responsible for two scratches on the loader. How do you think he would feel if one of his pins failed, damaged two cylinders, bent the pin pivot flanges, and put stress cracks in the paint?

*Who picks up the tab when the warranty expires? This is the most important question.

*I just spent $325.00, plus my time replacing the chrome rod on my LX885 lift cylinder. The last three threads pulled off the rod where the piston is attached. If the lock nut had been properly tightened, all of the threads would be missing. That is very unlikely to happen. Usually the entire threaded portion breaks off, and it is rare for even that to happen.

*Why did only three complete threads come off and remain in the locknut
(the locknut is in perfect condition)

*Why should I pay for the New Holland employees mistake?

*Did the NH employee also fail to properly install the nut on the other lift cylinder?

*If extensive damaged had occurred because the machine was operated after the break occurred, who would pickup that tab?

*Now that my machine is back together, is the repair 100%?

*Who is going to paint the marks in my cylinder gland caused by the pipe wrench. A proper wrench from Armstrong tools cost $430.00, I know because I called. Two NH service mechanics from different dealerships, told me they use a pipe wrench.

 

[wdchyd]

I would think the "Walmart" mentality kicks in when you buy a chinsy POS and demand it performs like a Mercedes......when you buy what you deem as a Mercedes (solidly built tractor) along with a Mercedes pricetag ($7000 for BH alone never mind the tractor and add-ons), I would hardly call this Walmart mentality.......

Unfortunately when I see something "Redesigned", I ask what and why did they design this.......too make something look better, work better, or make their bottom line better......where's the overkill when figuring stress points on crucial pivot points on a digging machine.......Yes, they do make lots of these with many with no troubles, but who's next and is it going to be a warranty issue or out of pocket for the next guy with this same problem......

If I bought a new hoe with a new tractor (which I did), I would expect reliability for the structure at the very least.......My BH65 has maybe 40+ hrs digging stumps last summer and I would be ripped if I was one of these two guys with the BH in question........:confused2:

 

[lhansman]

I had one of the pins in the stabilizers on my B21 break right in the middle a few years back after putting more than 1,000 hours on the machine. As I recall the center of the pin was a slightly smaller diameter to let the grease in and that is where it snapped. I have no idea what I could have done to break a stabilizer pin given the minimal amount of work they do but it happened. I installed a new pin and put a few hundred more hours on it without incident before trading for a B26.

I only have 320 hours on my B26 (which as pointed out has a similar hoe design to the BH-77) and it had done some hard work and lifted out some pretty large boulders without any problems.

Given the low hours on these machines I agree that as a minimum Kubota should replace the boom and both cylinders - and the pin!

 

[Tags]

I've had the main bucket pin ( the pin that attaches the bucket to the dipper stick) on my 161 excavator snap in half twice like your pin did. I think the reason for my pin snapping is fatigue over time because the pin actually has a hole drilled half way through it for greasing and I believe with a little wear in the bushings it allows the pin to flex ever so slightly over and over until it snaps right at the grease hole in the center.Obviously this is not the case with yours as it has no wear, but is it drilled to apply grease to one of the cylinders? If it is that may be the culprit, if not, it could just be a bad pin. Hopefully Kubota steps up and fixes the whole thing for you, boom and pin. It seems if it was a major design flaw everyone with a BH77 would be snapping pins left and right.

Also the reason for the curved booms on the bigger (and smaller machines for that matter) is it makes it easier to reach over the side of a truck when loading or when reaching over a wall to place something inside or reach over it.

 

[tbearnla]

The pin has no hole in it for grease it is a solid pin there is a grease fitting on the center ram to grease the joint, I was looking at mine today and I noticed the pin has no play in the bushings on each end but the rams are both loose on the pin. what it looks like to me and I am no engineer but when the center ram pulls and the outer ram pulls in the opposite direction,the pin flexes in the gap that is left between the pin and ram hole. I think if the hole on the rams was small enough to be snug on the pin it would not leave any room for it to flex. The slack between the ram hole and pin is big enough to see I can slide the 2 rams back and fourth. Just my own observation.

 

[Brad_Blazer]

The pin has no hole in it for grease it is a solid pin there is a grease fitting on the center ram to grease the joint, I was looking at mine today and I noticed the pin has no play in the bushings on each end but the rams are both loose on the pin. what it looks like to me and I am no engineer but when the center ram pulls and the outer ram pulls in the opposite direction,the pin flexes in the gap that is left between the pin and ram hole. I think if the hole on the rams was small enough to be snug on the pin it would not leave any room for it to flex. The slack between the ram hole and pin is big enough to see I can slide the 2 rams back and fourth. Just my own observation.

I agree with your theory that the pin is breaking due to a bending load and not a shear load. I think worst case is both cylinders pushing the pin in the same direction against the outer bushings. The pin may have been sized based on the double shear condition but with the extra clearance you describe the bending load is likely the culprit.

 

[SixHoeBob]

I agree with your theory that the pin is breaking due to a bending load and not a shear load. I think worst case is both cylinders pushing the pin in the same direction against the outer bushings. The pin may have been sized based on the double shear condition but with the extra clearance you describe the bending load is likely the culprit.

This is the correct analysis. Both cylinders bending the pin in the same direction, and then at other times both working to bend the pin in the opposite direction. Any pivot point becomes loose over time, even if properly greased.

Visualize the pin with the lift cylinder removed. The dipper cylinder is pushing/pulling on the center of the pin. There is plenty of unsupported pin between the cylinder and each boom bushing. That is the real culprit, and the lift cylinder is the icing on the cake.

A quality 4" dia. pin would not fail, nor a 3", nor a 2". 1.5" might be just right to span from bushing to bushing. There should be retainer bolts through both ends of the pin and corresponding bushing. The right hand bushing is to some extent flapping in the breeze on the flat steel plate of the boom.