L4310HST Air Cooled Transmission

[s219]

I noticed that two separate castings broke here. The lower case and the top cap / shaft bearing.

And look close, there is a crack at the left bolt mount in the second picture. Can't see if there is a corresponding crack on the right side.

For different pieces to fail, and for cracks to appear around that bolt mount in a separate location from the big cracks, it suggests to me that some extreme load was applied to the 3-pt. More than it could handle.

If I saw just one crack or cracks in one place, I'd think material defect. But to see multiple cracked pieces and some cracks in separate locations, that has to be from an extreme load.

I don't think the internal 3-pt hydraulics could do damage from the inside -- shouldn't they go into relief long before the mechanism has enough guts to break itself apart from the case? So that makes me think this was an external load or shock.

 

[s219]

I suppose a possible scenario is that something broke and came loose inside the case, and then was forced up into the case by internal gearing/rotation, and blew the case apart.

 

[newbury]

Did any of the first 2,050 hours of use involve a 3pt mounted backhoe?

 

[HCROW]

Did any of the first 2,050 hours of use involve a 3pt mounted backhoe?

I have no idea.

 

[Grandad4]

Sorry to see this, HCrow. This most likely resulted from some form of overload or shock loading on the 3 point toplink. In fact, there was a Grand Lxx10 that had exactly the same failure in a thread here on TBN a dozen or so years ago, complete with pictures looking nearly identical to yours. That one was from misuse of a logging winch, I think, but a 3 point backhoe would certainly be another attachment prone to such overloading of the toplink, and it's certainly possible to put extreme loads on the toplink in many other ways also. I wish I could locate that old thread.

Since I own the same tractor and used a logging winch, it certainly got my attention, and I've always made sure that pulling forces from the 3 point were as much as possible directed at the lower arms and not the toplink. It's water over the dam now, but Kubota offered toplink reinforcing kits for their B, L and Grand L models, which I also installed on mine, to minimize the chance of such failures. The early 2000's, when these tractors were sold, was the time when higher horsepower compacts were increasing in popularity and I've often wondered if this design - used on standard L tractors from the 1980's up to current models, was really adequate for the heavier Grand L tractors. When the next generation of Grand L's came out (the Lxx30's in 2003), there was a completely redesigned, much heavier 3 point mechanism.

I think a full repair would be well worth its cost, simply in re-establishing a decent sales value for that tractor. Some detective work at some salvage yards might turn up a replacement.