Backhoe Straightening Bent B26 TLB B/H Bucket

[CurtisC]

Working on a rock wall I managed to bend / rack the bucket on my B/H picking up a rock to where thumb and bucket teeth don't line up. (see pics) After getting a quote of $707 for a new bucket from the local dealer my current plan is to back up to a stout tree, swing the bucket against it and try to pull the rack out of it with a farm jack / come-a-long. Visually the wrist pin and bearing weldments on bucket, thumb, and dipper look ok but it won't take much deformation / misalignment to bind the pin (it may already be there) so I'm concerned my tree realignment therapy (if it even works) might add to the problem. Another option is to remove it and take it to a machine shop but because its racked suspect its a bigger job then just putting it in a press. Anyone ever had any luck or got any creative thoughts on straightening a bent B/H bucket?

As a footnote - thumbs are great but be wary of the closing power of the hydraulics vs. strength of your bucket. The bucket structure apparently can be overcome as it tries to close on an irregular, unforgiving surface (rock) and will yield before the hydraulic cylinder gives it up. This is problem gets worse the closer the contact point is to the pin as the closing force gets greater.

 

[rScotty]

My feeling is that a bucket ought not to be able to do that. All things considered, it sounds like the bucket might be made a touch on the light side. But from the picture it has worked OK lasted quite a while....so trying to fix it sounds good.

I'm not quite clear on how it got bent, but reading between the lines it may have happened when the thumb and bucket closed over an uneven load too close to the pivot point. Maybe while pulling on something at the same time?
If that's the case, the first thing I'd try is to put a similar uneven load on the other side of the bucket and then the the same thumb + bucket hydraulics ought to be able to bend it back. If that isn't enough force, you could add more force by using the dipperstick and boom hydaulics to push or pull on a corner of the bucket at the same time. One way to do that would be to hook a chain between one tooth and a big tree to pull while closing the thumb & bucket on an uneven load at the same time.
luck, rScotty

 

[Stonehaller]

I would be leery of trying to straighten the bucket against a tree while still attached to the backhoe as you may damage something else on the hoe. I would search for an outfit in your area that specializes in repair/rebuild of excavator buckets.

 

[Xfaxman]

CurtisC, chain the top of the bucket to something strong and use a bottle jack horizontally (with the pump at the bottom) to push the edge back straight. You will have to push slightly beyond straight to allow for spring back

 

[CurtisC]

Thanks to those who responded, I was able to at least pull the rack out and get the thumb and bucket teeth to clear with a farm jack, tree and chain (see pics). To Stonehaller's point I was very leery of getting further bending at the back support tube on the bucket or the connecting pin but best I can tell all the yield was out front where I wanted it. Besides trying to save down time & $$, I went the tree route for fear there might be enough misaligned that I wouldn't be able to get the bucket off and if I did it wouldn't go back on without a fight. The bend across the back is still there but everything works.
As far as the bucket being made a "touch light", the B26TLB is a pretty tough little machine and the bucket on the BT820 hoe has a goodly amount of steel in it for its size. I stand by my previous thoughts - be wary of the closing power on the bucket curl cylinder when using a thumb. Grabbing a heavy rock (or other irregular surface object) with enough clamping power to pick it up can put a lot of uneven stresses in the bucket, thumb, connecting pins and bearings - enough to permanently bend things up.

 

[rScotty]

Congratulations on the fix! It looks like that did the trick. No reason why that won't work fine now. I love home fixes like that. Particularly when they involve leverage, big forces, and bending metal the easy way!
My guess is that the pins and tubular bushings are fine; the forces required to bend those would be far greather than the forces that bent the bucket, with the connecting links being somewhere in-between strengthwise.

As for the bucket being a bit too lightly constructed, maybe on the B26 it was made that way on purpose to protect the rest of the system. I can't think of any other reason why something as common as an off center load could bend it. Designwise, it would be easy enough - in fact, easier - to make the stock bucket capable of handling any forces that the standard hydraulic system can provide. So if it bends, it might be a deliberate feature. As you've shown, a bent bucket sure beats a bent hoe in every way.

Our Kubota TLB is somewhat larger but from the same series. We often clamp loads off center and then curl the bucket in against full thumb pressure in order to hold something really tight. No problem with bucket wracking so far.
good luck, rScotty

 

[mdhughes]

rScotty & CurtisC , could it be that only one of the teeth from the bucket was touching the object being picked up and when pressure was applied that caused the bucket to rack? rScotty, in your picture is looks like you have the rock up on the side of the bucket, not just by the teeth.

 

[Gary Fowler]

I have abused my B26 backhoe to the fullest extent possible picking up rocks, trees etc and never bend or twisted anything. I only have 12" bucket so perhaps the larger bucket is what makes it weak. Also is your bucket pin on or QA. Mine is QA and doesn't look at all like yours ( the round pipe at the back is straight rather than angled as yours is in the photo.

 

[CurtisC]

I was trying to pickup a large rock, in the process the rock shifted and started to slip out ending up with most of its weight on one side of the bucket. In order to hang on to it I curled the bucket in further and apparently really loading up one side, also catching the rock between thumb and bucket side wall as it rotated out. A couple of other contributors as I see it - I have an 18" bucket while it looks like rScotty has a 12" - the wider the bucket gets the worse the force gets trying to twist it up when point loaded on an outer edge. Also the closing force gets greater the closer you get to the pin so I'd recommend grabbing rocks out by the teeth and not along the side wall which happened to me. To Gary Fowler's question my bucket is pinned and it used to have a straight back member, but after enough rock work with the thumb its slowly started to bend in a bit which it did little more after this last rock. Perhaps it doesn't have enough steel in it to make bullet proof but its what came from Kubota. I never had any issues digging in rock, it was only after I added a thumb and started grappling rocks that I started seeing the bending in the back, logs have not been a problem - just need to be a bit more careful around big rocks.

 

[Morning Wood]

If you have a mechanical thumb you have to be careful with bucket pressure. If you have a hydraulic thumb always close the thumb on the bucket, not the bucket on the thumb.