L35 - No front loader Tilt

[jiggseob]

The NUT has indeed come off that cylinder rod, thus the piston is detached from the rod. The thing clanging around inside that cylinder is a washer and the nut that threads onto those big threads. Some malfunction/mechanical failure caused that nut to back itself off. Its a nylock nut with a healthy amount of nylon lock that should take quite a bit of torque (~50 ft lbs) to overcome the nylock.

With the rod out of the piston, the oil flows freely through that hole in the piston, and no force is exerted between the pin-ends of the cylinder.

If that rod-thread is damaged beyond usability, I can almost guarantee that two replacement jobber cylinders will be less expensive than the replacement rod and nut from Kubota. Check those threads for damage. With that piston loose on the rod as the nut backs off, each cycle of the piston would have chewed those threads along the hole in the piston. From what I can see in your picture, those threads are kinda chewed up, but chasing them with a thread-die may clean them up and it might hold.

The piston is inside the bore of that cylinder. If it got a bit twisted or an o-ring rolled, that piston will be stuck in there HARD, and with the rod detached, theres no easy way to pull the piston out. That will be a challenge.

Before you commit to buying "seal kits" from the dealer, price the seals out. Get pricing on seals from your Kubota dealer and from a hydraulic supply / machine shop. Compare the pricing of repairing your cylinders against aftermarket/jobber cylinders from Shur-Lift or similar. It stands to reason that a few bits of nylon and rubber should be cheaper than new cylinders, but parts prices - especially dealer - being what they are, reason does not stand.

 

[TheOldHokie]

The NUT has indeed come off that cylinder rod, thus the piston is detached from the rod. The thing clanging around inside that cylinder is a washer and the nut that threads onto those big threads. Some malfunction/mechanical failure caused that nut to back itself off. Its a nylock nut with a healthy amount of nylon lock that should take quite a bit of torque (~50 ft lbs) to overcome the nylock.

With the rod out of the piston, the oil flows freely through that hole in the piston, and no force is exerted between the pin-ends of the cylinder.

If that rod-thread is damaged beyond usability, I can almost guarantee that two replacement jobber cylinders will be less expensive than the replacement rod and nut from Kubota. Check those threads for damage. With that piston loose on the rod as the nut backs off, each cycle of the piston would have chewed those threads along the hole in the piston. From what I can see in your picture, those threads are kinda chewed up, but chasing them with a thread-die may clean them up and it might hold.

The piston is inside the bore of that cylinder. If it got a bit twisted or an o-ring rolled, that piston will be stuck in there HARD, and with the rod detached, theres no easy way to pull the piston out. That will be a challenge.

Before you commit to buying "seal kits" from the dealer, price the seals out. Get pricing on seals from your Kubota dealer and from a hydraulic supply / machine shop. Compare the pricing of repairing your cylinders against aftermarket/jobber cylinders from Shur-Lift or similar. It stands to reason that a few bits of nylon and rubber should be cheaper than new cylinders, but parts prices - especially dealer - being what they are, reason does not stand.

Based on his description of how the failure occured my guess is the threads in the nut pulled out. If so good chance the rod is toast as well.

Dan

 

[jiggseob]

When I had my L3130/LA723 bucket tilt cylinder apart, the way it fits back together is the rod has about an extra inch of thread that protrudes out of the nut. In his picture, the farthest-out inch of threads is pretty flattened out. The inch of threads that is actually used to hold the piston on looks to be in better shape.

I would be interested to know why the nut backed out. My theory is that something on the loader is out of alignment, and that during extension / retraction cycles, the cylinder twists. During extension, the piston is pushing against the shoulder of the rod, and not twisting on the nut, so if the rod turns, nothing happens. During retraction, the piston is pushing against the nut, and when the rod twists in relation to the cylinder, then the piston will twist against the nut. Theres a flat-washer in there to take the twist, but maybe the washer is binding on the nut and applying twist to the nut. Each cycle the nut backs off a few degrees, over hundreds of cycles it takes the nut off to the point where the nut is only holding on by a few threads, and then lets go. As you see in the picture, the last 3 or 4 threads are messed up the worst. Just my theory as to WHY the nut appears to have backed off.

How to fix it? First get it apart and get the piston out. Getting the piston out will be a trick and a half. Then, see if the nut is stripped out; I doubt if it is, there would be more debris on the threads of the rod if the nut was totally stripped. Find a diagram that details the order of assembly of the parts.

My guess is that the rod with all of that extra thread was manufactured for an assembly that used two nuts locked against each other to not back off. In the interest of quick, easy, dumb-down assembly, they went to a 1-nut with nylock, and the extra rod length is just there. So to fix it right, obtain two appropriately threaded grade-8 or better nuts and lock them against each other. Throw the nylock as far as you can. Hopefully you can lay your hands on a metric thread die of the size to chase and clean-up those somewhat messed-up threads on the rod.

As far as seals, if the cylinder was leaking at the rod, replace only that seal and the wiper.

Edit.... Messicks has a diagram of the bucket-tilt cylinder for my LA723, I presume they will have similar for your loader. The nut is M20x1.5, thats the threading die you'll need to chase the messed-up threads on the rod.

Edit#2.... I read the list, a replacement rod (if needed) is going to be $683.93. Guaranteed you can get two replacement aftermarket cylinders for less than that rod.

 

[jiggseob]

Looked up L35, says it should have a TL720 loader, Messicks parts diagram lists the seal kit for $28.35. The seal kit for my LA723 bucket tilt cylinder is lists at $180.35.

TL720 loader bucket tilt cylinder diagram attached.

 

[Nicksacco]

Wow! Hopefully the cylinders are not scored and rod threads are not buggered up.

Rebuilding those cylinders is easier than most since they aren't as heavy.
The kits should have a new nut as well as the seals, but there are two versions of cylinders on the machine based upon the serial number of the machine.

The difference b/w the cylinders could be the rod nut diameter/seal types. Kindly keep this in mind.

 

[L35]

The NUT has indeed come off that cylinder rod, thus the piston is detached from the rod. The thing clanging around inside that cylinder is a washer and the nut that threads onto those big threads. Some malfunction/mechanical failure caused that nut to back itself off. Its a nylock nut with a healthy amount of nylon lock that should take quite a bit of torque (~50 ft lbs) to overcome the nylock.

With the rod out of the piston, the oil flows freely through that hole in the piston, and no force is exerted between the pin-ends of the cylinder.

If that rod-thread is damaged beyond usability, I can almost guarantee that two replacement jobber cylinders will be less expensive than the replacement rod and nut from Kubota. Check those threads for damage. With that piston loose on the rod as the nut backs off, each cycle of the piston would have chewed those threads along the hole in the piston. From what I can see in your picture, those threads are kinda chewed up, but chasing them with a thread-die may clean them up and it might hold.

The piston is inside the bore of that cylinder. If it got a bit twisted or an o-ring rolled, that piston will be stuck in there HARD, and with the rod detached, theres no easy way to pull the piston out. That will be a challenge.

Before you commit to buying "seal kits" from the dealer, price the seals out. Get pricing on seals from your Kubota dealer and from a hydraulic supply / machine shop. Compare the pricing of repairing your cylinders against aftermarket/jobber cylinders from Shur-Lift or similar. It stands to reason that a few bits of nylon and rubber should be cheaper than new cylinders, but parts prices - especially dealer - being what they are, reason does not stand.

No nylock on the piston retaining nut, on the L35 at least. They should be torqued to a 3 digit number with thread locker though. I imagine it had been previously rebuilt and the nut was not torqued correctly.

 

[TheOldHokie]

No nylock on the piston retaining nut, on the L35 at least. They should be torqued to a 3 digit number with thread locker though. I imagine it had been previously rebuilt and the nut was not torqued correctly.

I think we need to see the piston and nut. According to the OP the failure occured while he was using the bucket to hold the tractor on a hill and digging with the backhoe. That has the potential for putting a lot of tensile load on that nut.

Dan

 

[jiggseob]

I think we need to see the piston and nut.

Indeed... if that piston is jammed at the retract-end of the stroke, getting in there to apply force to the other side of the piston will be a challenge. Once all the pieces are on the bench and cleaned-up, it will be apparent what needs replacing.