Backhoe BH77 broke - defective part?

[wdchyd]

Yes, and the wider the pins bosses are, the less column strength the pin can handle before if breaks......

Kinda like breaking a full length pencil in your fingers vs breaking a short nubby pencil in your fingers....

 

[Tompet]

As others have mentioned the stress of the shared pin appears to be part of the problem. I had a Woods with the curved BH quite awhile ago and I went and looked it up. The Woods line of BH's, all with curved booms, solves this problem with separate pins for each cylinder that are inline for the same geometry. Likewise with the curved booms on the Kioti and the Cub/Yanmar.
Maybe someone can chime in with examples of other curved boom brands or larger excavator BH's wether the shared pin or in line separate pins is more common.

In Kubota's defense, I did look and it appears they use this shared pin design on all of there construction TLB's and I don't think anyone questions those BH's durability etc. And it does show support for Kubota's design of a curved boom. Hopefully, it turns out as a defective pin(s) and wdchyd and anyone else that has experienced this gets complete satisfaction in their repair or replacement from Kubota. IMO Kubota should take the lead if a batch of pins were defective or under spec. to start offering replacement pins to BH77 owners as a preventative measure because when this pin breaks it seems to immediately bend the "ears" even if op quickly stops.

 

[wdchyd]

Tompet,

My BH has not done this, I speak only as an armchair quarterback....My BH is a different setup and the cyls don't meet together.....The only experience I have in this is redoing goofups that happen to others that are out of warranty...:confused2:

Here's a pic of my setup.....the boom cyl is hidden inside under where it says Kubota on the side.....

 

[wdchyd]

Another view....

 

[Ductape]

My Woods BH80X also uses a shared pin for both the main boom and dipper cylinder, just as the Kubota hoe in question.

I'm just an armchair quarterback also, not an engineer or metalurgist..... but I have owned plenty of commercial equipment with hydraulics in my life. My opinion is that Kubota had a bad batch of pins. I don't see why that pin wouldn't withstand normal use (even plenty of abuse) if it were made out of proper materials, machined / hardened properly.

 

[Tompet]

Sorry wdchyd,
I wrote wrong name in that post, I meant to write TwinCam88.

 

[TwinCam88]

Good news - My dealer is picking up the BH77 today and says they will take care of the issue...whether it be just the pin or replacement of the whole boom assembly if needed. FWIW, they have already sold several of these new model backhoes and he genuinely seemed concerned that this issue may affect others...so, he wants to work with Kubota on a swift resolution. I have my fingers crossed.

 

[wdchyd]

Good news - My dealer is picking up the BH77 today and says they will take care of the issue...whether it be just the pin or replacement of the whole boom assembly if needed. FWIW, they have already sold several of these new model backhoes and he genuinely seemed concerned that this issue may affect others...so, he wants to work with Kubota on a swift resolution. I have my fingers crossed.

:thumbsup:

 

[tbearnla]

Twincam Please keep us updated on the outcome and what your dealer says about the pin situation. I talked to my dealer today and asked about any recalls and he said he would look into it. I am really thinking about going to a machine shop and having a pin made rather than having mine brake and sent to the shop with a crumpled boom and rams.

 

[Berniep]

Twincam Please keep us updated on the outcome and what your dealer says about the pin situation. I talked to my dealer today and asked about any recalls and he said he would look into it. I am really thinking about going to a machine shop and having a pin made rather than having mine brake and sent to the shop with a crumpled boom and rams.

If it's out of warranty the I would say go for it but if it's still in warranty then they will deny coverage because it's not a stock part.