Loader Loader boom pin or cylinder: which broke first

[BrookW]

In the middle of swapping the forks for the bucket one of the loader "holders" drooped. Obviously a curl cylinder is shot but I also see that one of the "pin fasteners" is missing. Pin fasteners are the sheer pins that hold the "pin" in place. The pin is a rod that connects the left and right loader arm holders probably to balance the forces and load.

So I got to thinking: Which broke first, the pin fastener or the cylinder? Does it matter? Could I have been operating with a broken curl cylinder for weeks and not known it because the good cylinder has been able to aide the bad cylinder via the pin? Full disclosure: I definitely maxed the loader with an unbalanced load recently.

Attached is a (JD 420) loader diagram (8 is the pin) and a couple shots of the loader including a closeup of the missing pin fastener.

 

[bumperm]

I would say it's very likely.

bumper - - is this one of those chicken and egg questions?

 

[BrookW]

Check.

 

[tawilson]

Are you sure the cylinder is shot? Without something tieing them together they will extend at different rates, the one with least resistance will extend faster.

 

[s219]

I have seen a few pictures like this on the Kubota forum when one side of someone's quick-attach comes undone but they don't notice until it's too late. On Kubotas, the cross rod is welded, and twists rather than breaking a shear bolt like what you show. Loading asymmetry causes the cylinders to get out of phase with each other. Normally, it's a matter of having the rod bent back straight. The cylinder hydraulics will sort themselves out with some actuation before putting it all back together.

So do you know for sure one of the cylinders is shot, or did it just get out of phase? Can you try getting the cylinders back in phase?

I suppose if one of they cylinders is shot, then lifting a heavy load in that condition could have caused the shear bolt to break as the load twisted everything.

 

[DK35vince]

There is nothing wrong with your cylinders.
The broken pin in the QA cross tube is causing the cylinders to run uneven.
All you need to do is fix the pin. Done..

 

[whis]

DK is right

 

[JCByrd24]

Yup, curl until they both bottom out and put a new pin in, done.

 

[BrookW]

I'm not certain the cylinder is shot. There are no leaks, bends, or breaks but one side moves in sync with the SCV and the other is slow to respond. It's as if the tractor had a stroke.

Both cylinders offer similar resistance when I push on them. I can get them lined up with brute force but as soon as I hit the SCV the right one snaps into action and the left one moves in slow motion.

If indeed there's nothing wrong with the cylinder why do the cylinders move at such drastically different rates? And why doesn't that eventually translate into a broken cross rod and racked loader arms?

 

[bumperm]

I have seen a few pictures like this on the Kubota forum when one side of someone's quick-attach comes undone but they don't notice until it's too late. On Kubotas, the cross rod is welded, and twists rather than breaking a shear bolt like what you show. .

I just went out to the tractor garage to look at my Kubota. It has a SSQA with a 1.25" cross tube welded similar to, but not were the OP's is bolted through the QA bracket pivot point. Mine is a few inches away from the bracket pivot which is completely separate. The Kubota SSQA brackets are 7" wide and the tube is welded on both flanges on each side. Looks to be pretty stout and I suspect would take a significant load differential to torque bend it.

Now I haven't tried lifting or pulling with one QA bracket disconnected, but I have pulled and lifted to max capacity off one side of the bucket and pallet forks, worst case without the backhoe on, it does is try to tip the tractor.