B2650 with BH77 Backhoe losing power on backhoe arm function

[Forest View]

When operating the BH77 backhoe, retracting the arm intermittently loses power. Typically, the tractor can be moved forward and backward with just the arm. But when the power kicks out, I can barely lift dirt out of a hole. I can sometimes sense when the arm power kicks out - it feels like a dead stick. I can always retract the arm when there is no load. The occurrence is increasing and it is getting harder to dig with any power. Pushing the arm out works fine, as well as all other backhoe and tractor functions. Is there a valve that is releasing pressure too soon? Is it a cylinder issue? What would cause this?

 

[jkcolo22]

When operating the BH77 backhoe, retracting the arm intermittently loses power. Typically, the tractor can be moved forward and backward with just the arm. But when the power kicks out, I can barely lift dirt out of a hole. I can sometimes sense when the arm power kicks out - it feels like a dead stick. I can always retract the arm when there is no load. The occurrence is increasing and it is getting harder to dig with any power. Pushing the arm out works fine, as well as all other backhoe and tractor functions. Is there a valve that is releasing pressure too soon? Is it a cylinder issue? What would cause this?

Check you linkages. Particularly at the joystick. My guess is that it’s a loose bolt rather than hydraulic.


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[Forest View]

Thanks for the input - will check tomorrow - assuming that linkages would be right under the joystick?

 

[dirtydeed]

yes, just remove the access panel. 4 bolts on the backside of the BH control.

Make sure that linkages are tight and squared up (not twisted). You'll understand once you see it.

 

[Forest View]

Everything looks in order

Would like to attach a photo, but could not load - help?

 

[Forest View]

See attachment of linkage photo

 

[Forest View]

At the bottom of the linkages there seem to be some adjustments - is there an adjustment that would change the amount of pull in the arm? (Wondering why it would have changed...)

 

[mdhughes]

Take a look at DIY My Way's video he did on the BH77:

Kubota Backhoe Maintenance: Adjusting the Control Linkages (#81)

 

[rentthis]

Just a shot in the dark. If you have quick disconnect fittings, disconnect and reconnect them firmly. Sometimes they cause odd things.

 

[Forest View]

To mdhughes: Great video! Thank you. I found exactly what you found in the video and tightened the linkages and to prevent issues used cotton swab of hydraulic fluid on the top of each piston / dip stick, along with some WD40 on the arm joints. Certainly improved the feel of the controls, but the problems remains. In fact, the reduced arm pull back power became more apparent (when it occurs). It is only this one motion/function (arm retraction); no other functions of the hoe are affected. Anyway, thank you and I welcome other suggestions. PS. I liked and subscribed!

To rentthis: Easy to do, so I will do what you recommend. From what I know, there is only one quick disconnect for the BH77. Since only the one motion/function (arm retraction) is affected, I question if the quick disconnect is the issue. I'l check it and let you now if I find anything.

Today's update: (Just focusing on arm retraction, as all other functions work correctly). With the linkages tightened (thanks mdhuges), I tried digging again. Normally, when I retract the arm with a firm bite in the soil, it will pull the tractor backwards, often times with the stabilizers firmly planted. The problem presents itself this way: pull back on the joy stick (arm retraction) and the arm will start to pull for a microsecond, then feels like it goes limp. I can always lift up and retract the arm, but not with a load. I can then extend the arm and on the next joy stick pull back the arm may have full power or it will repeat the failure. I'd estimate that the failure occurs more than 50% of the time. It's early yet, so I cannot (for sure) say the problem is getting worse (more common), but I suspect it is.

Ideas appreciated!

 

[nbryan]

When operating the BH77 backhoe, retracting the arm intermittently loses power. Typically, the tractor can be moved forward and backward with just the arm. But when the power kicks out, I can barely lift dirt out of a hole. I can sometimes sense when the arm power kicks out - it feels like a dead stick. I can always retract the arm when there is no load. The occurrence is increasing and it is getting harder to dig with any power. Pushing the arm out works fine, as well as all other backhoe and tractor functions. Is there a valve that is releasing pressure too soon? Is it a cylinder issue? What would cause this?

When you say "arm" you mean dipperstick? Or boom? The arm (dipperstick) is what I curl or push out with the bucket on the ground to move the tractor. The boom to raise loads or push the tractor up off the ground. Does it happen the same when the boom and dipper are fully extended when you try and raise them? Or when the bucket is closer to you - the boom partly raised? If I had a clear sense of the positions, motions, and loading of your boom, dipper, and bucket when it loses power, I could try and duplicate on my BH77. I'm interested as I've also seemed to have intermittent loss of power or control at times, but the next digging foray there's nothing wrong!

 

[Forest View]

When you say "arm" you mean dipperstick? Or boom? The arm (dipperstick) is what I curl or push out with the bucket on the ground to move the tractor. The boom to raise loads or push the tractor up off the ground. Does it happen the same when the boom and dipper are fully extended when you try and raise them? Or when the bucket is closer to you - the boom partly raised? If I had a clear sense of the positions, motions, and loading of your boom, dipper, and bucket when it loses power, I could try and duplicate on my BH77. I'm interested as I've also seemed to have intermittent loss of power or control at times, but the next digging foray there's nothing wrong!

Yes, arm = dipperstick. Boom lifts up and down, arm is between the boom and the bucket. I haven't checked all different positions of failure yet, but it fails with the boom halfway out, and the bucket digging into the dirt from the surface to 3' down. The bucket is pulling through the dirt, so the bucket is loaded and the arm pullback often fails in this condition (so under medium to high load). Normally, in this condition, the arm would pull the tractor back quite hard. The arm retraction work fine without any load.

 

[dirtydeed]

Here is another thread that had a similar issue. http://www.orangetractortalks.com/forums/threads/back-hoe-boom-issue.24114/

Looks like the problem was with the spool valve that controlled that function. Perhaps it had some crud in it. If your machine is new, I'd suggest that you have your dealer look into it as long as the joints on the control linkages look ok (squared up). I had a similar issue early on that I corrected by adjusting the linkage. It seemed like you had to have the stick in just the right position in order for my swing to one side to work correctly.

Anyway, maybe this thread will help.

 

[Forest View]

Please see the photo of the BH77 backhoe hydraulic controls. The one with the duct tape on the shaft in the control for the dipper stick, (both out and in) (believe this is called the spool valve). I noticed the screw and nut on top of the control and decided to open it up. After powering down the tractor and putting the dipperstick into the down (neutral) position, I took the nut off the top of the control. A minor amount of fluid came out and I put nut back on. While the nut was on, but loose, I turned the screw out and back in to where I thought it was originally, then tightened down the nut.

Good news ...after about 1/2 hour of use, the problem is gone and the dipperstick seems to have the power it had prior to the 'kicking out' problem. So, yes, I believe that "dirtydeed" was correct about crude in the spool valve. I did not see any crud come out, but had a tablespoon of fluid come out.

Can anyone tell me what this adjustment does and any advice on how to set it?

Thanks for all the help out here and sorry it took so long to follow through on this post.