MX5400 hydraulic arm shaft and control rod damage

[DWilly]

Quick update. The dealership returned my tractor on Wednesday. Everything covered by warranty as promised. Parts delivery was delayed, par for the course these days. I asked for the damaged parts - they seemed easily fixable for spares - but since the warranty covered the work Kubota wanted them. Fair enough.

As for potential design defect, you can't make a definitive judgment based just on the fact it was covered by warranty. It does seem like an acknowledgement that abuse can't necessarily be assumed as the cause. Also possible they just made a business decision based on the fact it's a brand new machine, the repair costs were insignificant to Kubota, and the kind of damage is so apparently rare that they don't have much worry that everyone is going to be coming in for similar warranty claims. Time will tell on that last part.

 

[30acres]

This exact same thing just happened to me. Your pictures look almost identical to what mine looked like. Unfortunately I didn't take any pics of the damage. I consider myself relatively new to farming, tractors, etc.

I have an MX4800, with about 850hrs on it. I bought the corresponding backhoe, the BH92, this is relevant because that equipment adds steel plates that stick out from the back of my tractor and may have played a part in what happened to me. My tractor came with those twist-style stabilizer arms, which broke a long time ago so I replaced them with https://www.eparts.shop/solid-telescopic-stabilizer-for-kubota-e-l8430-3. I do not have quick-attach.

The specific implement I was using when it happened is a 64" offset flail mower: https://www.farmerequipmentsales.com/store/p30/64"_Boom_mounted_Flail_Mower.html

I like to cut my tall grass with this mower fully off to the side (the right side) so I can drive in the grass I have just cut and the mower works in grass that has not just been driven through and flattened by my tires.

I usually pin my telescopic stabilizer arms such that the implement can move a little in case it needs to "go around" something. But when I do that, both 3pt arms swing to the right and the right 3pt arm (as seen from the back) ends up "leaning" against the right-hand backhoe plate I mentioned earlier. In retrospect, having my right-hand 3pt arm lean on the right-hand backhoe plate probably kept this from happening last summer.

This year I noticed that all this leaning of my right-hand 3pt arm (i.e. the lifting rod) into the right-hand backhoe plate is causing my right lifting rod (i.e. the one that is adjustable) to start bending. Therefore I pinned my telescopic stabilizer so that my right lifting rod is not leaning on the right backhoe plate. After about 4 hours of cutting, it broke, exactly the same way yours did.

By not being able to lean up against the plate, I believe that all the lateral weight was being carried by the arms. Also, because my implement is all off to the right side, there would be alternating forces on my two 3pt arms (i.e. a downward force on the right arm and an upwards force on the left). At some point the clip holding the rockshaft must have broke and the whole shaft shifted right, causing the left lift arm to fall off.

 

[loggin]

So the take-away here is that the retention plate of the lift arm is likely somewhat inadequately designed. And that hanging weight and/or engaging ground work off to one side places considerable stress on the 3 point hitch. I suppose the arm slipping off is better than having the cast iron case cracking or breaking off.

Either way it is also important to remember this is a lighter ag tractor and the manual states that a rear implement is limited to a weight of 1,000 pounds. Hanging weight and ground engagement off to one side increases stresses and multiplies these stresses as the distance away from the machine increases.

Just some things to consider.

I am sorry you guys had this happen to you and I would like to thank you for bringing it to our attention!!