BH90 dipper stick piston bent or broken

[Bob53]

I like you're way of thinking, smaller tool just take longer. I've only used the BH75 hoe so nothing to compare too, although i really do not think i was doing anything out of ordinary. first time just trenching through roots which was breaking through roots, besides hearing roots snap though hear clinck and there went the clylinder. Hard to understand how some other say they have dug many stumps roots with no problems. And hard to know if you're going to snag something when digging that is going to cause problem.
good luck the the BH90 hope you get things worked out.

 

[enumclaw]

Yes Bob53, anything can be broken but a well made product should not break during normal operation. If you drop a light bulb on concrete, the bulb will break but the bulb should not explode flinging glass shards like shrapnel when you flip the light switch to the on position. I knew that the BH90 had limitations when I bought it. Compared to a Case 580K, it is a light duty backhoe but to me that means that it can't dig as fast, smaller bucket, as deep, shorter boom and dipper stick or pick up as much weight not that it will break without warning when you are digging. How will you ever know if you are approaching it's limits? I had read a book about backhoe operation when digging ditches which showed some interesting techniques that are no doubt commonly used by commercial backhoe operators. After digging a ditch, say up to a wall, how do you get the backhoe which is straddling the ditch over the ditch? You pivot the boom to one side of the ditch, lift up the rear wheels by extending the boom and then pivot the body of the backhoe until both rear wheels are on the same side of the ditch. Then you put the rear wheels down, push down with the loader until the front wheels are off the ground, then backup until the front wheels pass over the ditch. I learned that the BH90 on my L4330 was not strong enough to do this, at least not with me on board. I accept that limitation and plan for it while ditching. It didn't break the boom cylinder when I tried to pick it up, it just wouldn't do it.

 

[HammerFour]

If it is bending and breaking the cylinder rod, that sounds to me like the rod is getting in some sort of a bind....

Is it possible that the end of the rod is getting bound up while exerting a lot of ( side maybe? ) force on the bucket?

I am picturing in my mind the bucket being used to scrape across the stump/dirt pile, the bucket binding on its pivots, the cylinder trying to extend/retract to open or close the bucket and since the bucket is bound up at the pivots, the rod bends or breaks....or maybe not.

 

[Bob53]

HammerFour, Mine is bending breaking when I pull up on the control that raises the biggest( closest arm to tractor). That is when the largest clylinder(one right below dipper cylinder pull in) raises the 1st biggest arm on the hoe.
This puts a lot of stress on the dipper rod if extended out .
So the problem is actually happen when the biggest cylinder that is below the dipper cylinder contracts. sorry do not know all the names these cylinders. Happen same both times.

 

[enumclaw]

Hi Bob53. The Kubota dealer fixed my BH90 under warrenty and I have some before and after pix that you might want to compare to your tractor. I have not exercised the BH90 yet but I do believe that they corrected the problem. The pic Mechanical_Stop shows the underside of the boom-dipperstick hinge. Note the square plate near the top of the boom. This plate is a mechanical stop. While extending the dipperstick piston, the dipperstick will contact the the mechanical stop before the piston has reached the end of its travel. As the hydraulics continue to push, something has to give and since the dipperstick cannot move the piston bends. Continued in next post.

 

[enumclaw]

Continuing Bob53, see in the attached pic that the dealer has removed the mechanical stop.

 

[enumclaw]

The wrong pic was posted. I will try again.

 

[enumclaw]

An in this final pic, the dipperstick piston is at full extension and the dipperstick does not contact the boom. If I use the controls to try to further move the dipperstick, you can hear the bypass as the piston is already at full extension. So, I would examine your backhoe for that mechanical stop. It is interesting that the plate is only about .5" thick so if the piston were only a little shorter, this problem would not occur. I do think that this will solve the problem as I don't remember ever hearing the sound that the hydraulics make when the piston is bottoms out before while I had been working. Time will tell.

 

[Bob53]

thanks enumclaw

I'll have to check mine this weekend when i go up to use it.
I'll have to see if the BH75 has a stop and when it hits the stop. if it does going to have to contact kubota and let him talk to dealer. my dealer already told me nothing else they can do.i guess my other option is another dealer for fresh look. Thanks again, i'll let you know if i have any luck.


Bob

 

[enumclaw]

Ok Bob53, I'll be interested to read your report. And in my haste to post, I forgot to say, kudos to Kubota for standing behind their products and especially to my Kubota dealer, Gary at Issaquah Kubota for outstanding service far above and beyond what you might expect. I highly recommend that you patronize Issaquah Kubota if you are in the Western Washington region.