broken lift arm shaft

[Jerry/MT]

how could you hold on to the lift arm internally if you are able to slide out complete rockshaft. The clip only keeps the lift arm from coming off the shaft. What pushes the ram rod internally is rotation of rockshaft along with the internal lift arm. you withdraw the shaft and what is holding the internal lift arm?

Jc,

I think it might be do able with several big IF's.

If the piston is fully retracted then, the piece that rotates the rockshaft (#48, rockshaft actuator), which is pinned to the piston rod, will keep the that part from falling down. It may try to rotate about the piston's axis but a small rod placed through the hole in the rock shaft actuator can keep that alligned.


The big IF is can you slide the rockshaft out leaving the rockshaft actuator in place and then slide the new rockshaft through all three holes? I think #48 also has to be in a specific position to get the full range of motion for the lift.

I don't think those bushed holes are a sliding fit. I think they maybe a press fit. If that's the case, the lift cover has to come off or you need some special tools. If they are a sliding fit then I think it' s worth a try

 

[JC-jetro]

I think it might be do able with several big IF's.

If the piston is fully retracted then, the piece that rotates the rockshaft (#48, rockshaft actuator), which is pinned to the piston rod, will keep the that part from falling down. It may try to rotate about the piston's axis but a small rod placed through the hole in the rock shaft actuator can keep that alligned.


The big IF is can you slide the rockshaft out leaving the rockshaft actuator in place and then slide the new rockshaft through all three holes? I think #48 also has to be in a specific position to get the full range of motion for the lift.

I don't think those bushed holes are a sliding fit. I think they maybe a press fit. If that's the case, the lift cover has to come off or you need some special tools. If they are a sliding fit then I think it' s worth a try

Jerry,

I opened mine to change the piston seal and just can't see how one can man handle the rockshaft out, pressed or fitted and be able to align all the spline with the floating in the air "actuator". ram rod is pinned to the actuator but the whole thing will slide off if the rock shaft some how is withdrawn.

I have no doubt the position of spline in the rokshaft, lift arm and "actuator arm" is very important. If I had to do it then I would have put a witness mark on the rockshaft and the lift arm when the lift arm is fully down and inspect the position of the inside arm to line it up how I found it. I'm sure there is a procedure for it if you have not marked it correctly. Unfortunately, there is so much sheet metal on a platform tracotr to be taken off that makes this job time consuming. I know on mine a good stout shade tree and a come along a nylon sling is all I need to take the cover off when needed.

JC,


Jerry, the ram rod is pinned to the actuator but piston is just freely slides up and down the cylinder.

 

[JC-jetro]

thanks for the input so far; i was able to take a couple of photos. one showing the broken shaft and liftarm together, the other showing the opposing lift arm move out a little after taping on the broken side. Hope this clarifies.

Thanks again, Bob

Oh my!! so sorry to see that. darn thing just twisted off. I think you're lift arm still is good. Have you looked at the picture I posted. I can envision a possibility where you take the front lift cylinder head off and then withdraw the piston. Then one can hold the lift arm while a helper is taking the rockshaft out. The installation will be reverse of that while a guy is trying to line up the splines internally. I think it will be awful darn hard. Taking the cover off is doable if you have patience.

JC<

 

[Fastdraw]

Oh man that sux...I think the top plate will have to be removed. Unless all of the internals are in just the right place , when you take out the shaft, youll never get it to line up right. Its not that bad to take off the top plate though.The ROP and fuel tank will have to come off, theres 4 17mm bolts holding the rop on, 2 16mm bolts holding the fuel tank on and a few 13mm bolts holding the fenders on. Get those off and you should be able to manage it from there.

 

[Jerry/MT]

Jerry,

I opened mine to change the piston seal and just can't see how one can man handle the rockshaft out, pressed or fitted and be able to align all the spline with the floating in the air "actuator". ram rod is pinned to the actuator but the whole thing will slide off if the rock shaft some how is withdrawn.

I have no doubt the position of spline in the rokshaft, lift arm and "actuator arm" is very important. If I had to do it then I would have put a witness mark on the rockshaft and the lift arm when the lift arm is fully down and inspect the position of the inside arm to line it up how I found it. I'm sure there is a procedure for it if you have not marked it correctly. Unfortunately, there is so much sheet metal on a platform tracotr to be taken off that makes this job time consuming. I know on mine a good stout shade tree and a come along a nylon sling is all I need to take the cover off when needed.

JC,


Jerry, the ram rod is pinned to the actuator but piston is just freely slides up and down the cylinder.

I see the piston not attached to the rod. I agree with your point. Thanks for pointing that out.

 

[jinman]

Maybe I'm missing something, but why not put a 2" PVC pipe into the left side hole where the shaft is broken and drive out the shaft on the right side after removing the lock ring? As the PVC drives out the shaft, it will support the lift arm and keep it from dropping. Put the new shaft in on the right side and drive the PVC out as the rock shaft is inserted. It sure seems doable because spline alignment is only important to the position of the rockshaft arms, not the lift lever inside the case.

 

[Stonehaller]

Maybe I'm missing something, but why not put a 2" PVC pipe into the left side hole where the shaft is broken and drive out the shaft on the right side after removing the lock ring? As the PVC drives out the shaft, it will support the lift arm and keep it from dropping. Put the new shaft in on the right side and drive the PVC out as the rock shaft is inserted. It sure seems doable because spline alignment is only important to the position of the rockshaft arms, not the lift lever inside the case.

I agree with Jinman's basic concept of supporting #48 with whatever you drive the rockshaft out with, however, I think you might have to drive the shaft the other way from what Jinman says. There has to be a difference in diameters for the rock shaft to fit through #48 and engage a spline. Since there is only one #27 bushing, I suspect the opposite side of the rockshaft is the larger diameter so you would need to drive the shaft from the non-broken end. If you get the lift arm off the right side you could check the diameters on each side. My guess is the bore through the casting is the same on each side. However, if the bore on the left is the same as the ID of the bushing, then you need drive the shaft from left to right and push the bushing out at the same time. You would probably need something stronger than PCV to drive the shaft in that case.

EDIT: Of course, if you buy the new shaft first, it should be obvious which way to drive it out.

 

[JC-jetro]

The idea is worth a try but 2" pvc dia is larger than the rocskshat dia, driving it out with a PVC is problematic as pvc is too soft. A piece of emt or any pipe might be better. if the OD of pipe is smaller than id of lift arm then you might be able to driving it out but the key is not to drive it all the way as lift will spin around the driving pipe. Ram rod and the lift arm is pretty heavy. I think it is going to be very hard to line up spline of the new shaft with the spline of the lift arm blind folded.

Unfortunately , in the long run taking the lift cover off is going to be least effort overall.

If I were to give it a try short of moving the lift cover would certainly be like I explained by removing the head and asking a helper to line up the spline thru the cylinder opening freed up by removing the head.

JC,

 

[SPYDERLK]

Maybe I'm missing something, but why not put a 2" PVC pipe into the left side hole where the shaft is broken and drive out the shaft on the right side after removing the lock ring? As the PVC drives out the shaft, it will support the lift arm and keep it from dropping. Put the new shaft in on the right side and drive the PVC out as the rock shaft is inserted. It sure seems doable because spline alignment is only important to the position of the rockshaft arms, not the lift lever inside the case.

I had to replace the internal rocker arm/lift lever that broke with a heavy implement on a Kubota. As I recall, all arms, inside and out are specifically rotationally located for correct geometry during lift. This would add complexity, but may not be a killer to rockshaft replacement while assembled.
larry

 

[JC-jetro]

I had to replace the internal rocker arm/lift lever that broke with a heavy implement on a Kubota. As I recall, all arms, inside and out are specifically rotationally located for correct geometry during lift. This would add complexity, but may not be a killer to rockshaft replacement while assembled.
larry

Absolutely, that's why in absense of having a written factory directions, one need to have proper witness mark on all compaonents, Rock shaft and lift arm externally and what that translate to position of arm inside. This can be done with lift arm fully up or down, no matter, but much easier with the arms down and in rest.

JC,