BH75 Piston broke, twice! Design problem??

[ArkCivEngr]

I have the tendency to back up too close to a stump and wind up having to dig (and curl) a bit with the dipperstick fully extended. I'll keep that in mind.

Your dealer isn't doing you right. /forums/images/graemlins/mad.gif With all these problems, and having their engineers clear you of overworking the hoe, they should be coming through with weekend loaners. Keep after them. I've seen many threads on several boards and big problems like this almost always get solved by "moving up." The squeaky wheel gets the grease.

 

[Volnavy]

OK guys, here is a link to the clip. It is 10 MB so I can't attach it.

http://web.utk.edu/~hines/tractor/backhoe.mpg

Watch the dipperstick cylinder bend when the bucket curls. Do this several times and the piston breaks due to fatigue failure.

I called Kubota again this morning, they pushed me up the line, but all I got to talk to was the recording machine. I've hit my limit. My stance is currently, pick it up and give me a loaner or pick it up and give me my money back.

This should prove it is not my fault, it is their fault, so they should bend over backwards to make me happy. The line that "This is a new product" should not be uttered. They should not put a product out before fully tested.

 

[Av8r3400]

The clip doesn't work. /forums/images/graemlins/frown.gif

EDIT: Nevermind, problem on my end, now fixed.

 

[qqq]

</font><font color="blue" class="small">( Well, if you just extend the bucket back down, you would have a lot of leverage against the dipperstick cylinder. The leverage from the curled bucket may be enough to bend the dipper stick piston. I don't know whether to test this hypothesis or to try to avoid it. )</font>
The video seems to confirm your earlier theory. At about 2 seconds into the 12 second video clip, its pretty clear that as you curl the bucket, the dipperstick piston bends quite a bit. Its too bad you weren't around when Kubota's QA engineers came out. Seems like it would have been pretty easy for you to demonstrate how to get the piston to fail.

I'd be frustrated too if I were in your shoes. Hopefully Kubota will come through. If you have a name and number for the QA folks, I'd call them as well. The squeeky wheel gets the grease, and you definitely have a very legitimate gripe in my mind.

 

[SkyPup]

You'd think they'd come right out with a brand new replacement BH and take the defective one to research why it failed? /forums/images/graemlins/confused.gif

 

[JerryG]

Now that you have shown the movie, It is easy to see what is going on.

In the film all three cylinders are putting pressure on the teeth. The bucket teeth are turned at the worst possible angle to dig. The manual should have a series of pictures that demonstrates how to angle the bucket to dig. By angling the bucket the way that you are, you are putting even more pressure on the entire backhoe, because as you are rotating the bucket to dig, you are in effect lifting the tractor and backhoe. When this lifting doesn’t happen, that is when the cylinder bends. The intensity of the situation is far less, the further the bucket is from tractor, because several of the angles change. This is the way it is sometimes when a new person starts using a backhoe. If you keep it and continue to get experience and listen to what I said above, the problem will go away. I don’t mean to be cutting you down or being mean in anyway, just that that is the way it is sometimes.

I am sure that I will get a lot of flack, flaming etc. There will even be some that will say that no matter what Kubota should take care of it. There will also be some that will say that no matter what, It shouldn’t have ever happened and wouldn’t have if the relief worked or the engineering was right or that the metallurgy is right. Well guys, these small hoes cost anywhere from 5k to 10k. They are made to where they will do the job for most people and cost the manufacture the least. Yes, they could build a hoe that wouldn’t do this under any circumstance, but how many people would buy a hoe for a compact that cost in the 20k range? There is always a weak link in everything. More money and over engineering would just move the point of failure. Kubota will try to make you happy. They will replace cylinders and they may change out the relief valve

 

[guyrj33]

I don't know where to start.
Kubota should make this right.
The dirt shown in the video is soft loam, and should be easy digging.
Of course there is pressure on all 3 cylinders, that's why a backhoe works. Imagine how poorly a backhoe would work with pressure removed from any one cylinder.
Backhoe manual recommends using bucket curl for difficult digging.
It's ok to dig close to the tractor.
Why are you making excuses for Kubota when there is an obvious problem.
Guy

 

[JerryG]

<font color="blue"> Why are you making excuses for Kubota when there is an obvious problem. </font>
Because it is more than likely more operator inexperience than anything being wrong with the hoe. This is not just Kubota. I have seen this happen on almost all brands of backhoes. Once in a great while it will be a relief that is causing the problem, but most of the time, the problem goes away as the operator becomes more experienced.
<font color="blue"> Kubota should make this right. </font>
I am sure that they will try.

 

[ByronBob]

What does the manual say? Is there anything in there that says you can't do this?

 

[Stef]

This is not normal... Kubota must do something.