Backhoe New Kubota L3800 w/BH 77, Boom will not lift rear of tractor

[Wargreen]

I have a brand new kubota L3800 hydro tractor with a BH77 Backhoe with only 3 hrs on it. With the loader bucket on the ground, the backhoe boom will not lift the rear wheels off the ground. The dealer told me that it's probably because the tires are loaded. I think it should easily pick up the tractor. My old 1979 tired woreout B6100 backhoe w/loaded tires does it easily.

The dealer does not have another tractor/backhoe combination in stock to compare. I have asked the dealer to send out a svc tech to check pressures. Hopefully they'll find the problem.

Am i asking too much out of this backhoe? Has anyone else had this problem?

Thanks, Warren

 

[JoeBuyer]

There is another thread titled:

L3200 and backhoe capacity/power and operating temperature

You might have similar problems.

 

[bulldog69]

Compairing those 2 machines is kind of like apples and oranges. The B6100 weighs half as much as the L3800. The BH is about half the weight, and the loaded tires are so far apart they're in a different zip code. Loaded rears on the L3800 adds at least around 600 lbs of extra weight. With that being said, look at what you have.

These are just ball park figures, 3300lb tractor, 1000 lb loader and 1000lb backhoe + operator = around 5500lb machine. Now, when you have the loader bucket on the ground and try to lift the rear with the BH bucket it's trying to pick up a 5500lb load. The loader being down creates a leverage point so to speak and this will increase the load on the BH. I bet if you try to lift the rear with the loader up it will be much easier.

I formerly had a B7100 with BH and loader and currently have a L3000 with BH and loader. The newer Bh looks much heavier built and probably is. But when it comes to outright digging force, the B7100 was much stronger. Of course the multi stage pto may have been the difference between the 2.

Here's how I looked at it. If the Kubota wouldn't do it, it probably wasn't designed to in the first place. If it couldn't do it then I probably needed a CAT.

 

[LD1]

Do the out riggers lift the back tires up?? Are you having trouble digging?? When trying with the boom to lift, is it extended out far?? Or in tight?

 

[Wargreen]

When I tested the tractor at the dealership it would pick the tractor up with the FEL on the ground easily at idle. Now with the tires loaded and even rev'd to 2500 rpms it will not.

It will pick up the tractor when the FEL is off the ground and does seem to dig well. The outriggers will also pick up the tractor easily. To answer LD1's question the boom is extended approximately mid way.

Yes, I agree the B6100 & L3800 are apples and oranges weight wise. I was expecting a little more power out of the main boom but may be expecting too much. I appreciate the insight.

 

[LD1]

With the loaded tires, indeed I think you are expecting too much. Even my large Ford 5500 (I know it is older and weak compared to new industrial TLB's) has a hard time lifting itself with the boom extended midway or beyond.

But the boom isnt really where the digging force comes from. Its the dipper and bucket. you dont want to apply so much downforce that your rear comes off the ground.

Maybe I am wrong, and maybe you do have a pressure problem. But I think it is just the case of expecting too much for a backhoe "attachment" and having loaded tires.

 

[jenkinsph]

Having a tlb myself it is one of the problems of having an 8 in 1 tool, things get compromised. The tlb will work fine without the rear tire ballast, the backhoe should be sufficient for loader work. When you remove the backhoe and need to use the tractor for high draft loads you will need to be in 4x4 for sure. It won't be as good as having loaded rear tires but as I said it is a compromise. I solved that problem by buying the 4520 with about 1100 lbs of iron weights and no loader in the way.

 

[Redneck in training]

When I tested the tractor at the dealership it would pick the tractor up with the FEL on the ground easily at idle. Now with the tires loaded and even rev'd to 2500 rpms it will not.

It will pick up the tractor when the FEL is off the ground and does seem to dig well. The outriggers will also pick up the tractor easily. To answer LD1's question the boom is extended approximately mid way.

Yes, I agree the B6100 & L3800 are apples and oranges weight wise. I was expecting a little more power out of the main boom but may be expecting too much. I appreciate the insight.

The tractor has positive displacement pump therefore rpm have no effect on pressure only volume. Idle or high rpm affect speed of operation but not force.

 

[rjwerth]

I don't think you should expect to pick up the tractor w/loaded tires and the loader down. It's just not going to happen.

 

[Wargreen]

Jenkinsph & Redneck, Great information, Thank you