broken hydraulic cylinder on BL4690 backhoe

[bigbenkubota]

Its been a few weeks and I'm at something of a roadblock.

I've attempted to loosen the retainer ring with a few different methods. I also took it to a tractor shop and they could not loosen either. Its an aluminum ring and it has both cracked and wallowed out but would not spin. It seems like there might be a bulge starting on the steel ring because of the cracked piece pressing outwards. The shop thought they could probably get it apart with a couple hours of work, but not knowing what the condition of the inner wall of the cylinder would be we decided its not worth the effort.

Kubota does not make the entire cylinder assembly (part 70050-93783) anymore.

I've looked at online sources for similar cylinders, however it appears that because the size isn't going to match (I can't find one as long as this with a 1 1/8" dia. rod) the operating speed is going to be quite a bit different.

I'm currently talking to a couple places about them building me a new assembly. I haven't heard back yet what that will cost.

Any other recommendations for things I haven't tried yet?

 

[D2Cat]

Its been a few weeks and I'm at something of a roadblock.

I've attempted to loosen the retainer ring with a few different methods. I also took it to a tractor shop and they could not loosen either. Its an aluminum ring and it has both cracked and wallowed out but would not spin. It seems like there might be a bulge starting on the steel ring because of the cracked piece pressing outwards. The shop thought they could probably get it apart with a couple hours of work, but not knowing what the condition of the inner wall of the cylinder would be we decided its not worth the effort.

Kubota does not make the entire cylinder assembly (part 70050-93783) anymore.

I've looked at online sources for similar cylinders, however it appears that because the size isn't going to match (I can't find one as long as this with a 1 1/8" dia. rod) the operating speed is going to be quite a bit different.

I'm currently talking to a couple places about them building me a new assembly. I haven't heard back yet what that will cost.

Any other recommendations for things I haven't tried yet?

BigBen, the part I put in red....did you, or the tractor shop, get the little square piece of metal unwrapped from the end of the cyl? If that retainer is not removed, trying to unscrew the end piece will not happen.

Once again, that retainer is simply a piece of key stock that is wrapped around the end of the cyl that goes in a groove to lock the end cap in place. That key stock had a little hook (bend) on the end so you know when it's in place and to remove it when servicing the cyl. In your picture the end/hook has been broken off.

You could weld something on the end of the broken off piece to get a better grip. If you have no access to that, you could get a piece of key stock. They are available in 12" lengths at most farm or good hardware stores. I would guess it's 1/4" or close. It just needs to fit in the slot, dimension is not critical.

You could actually use something round and bend it the same way. It's just a punch!

Take a piece of 2" or 3" pvc pipe, or anything else you have to use as a form. Put the pvc in your vice. Clamp the piece of key stock to the pvc with a vicegrips. Begin to wrap the key stock around the PVC. You just want to get a bend started.

The cut the key stock to about 2"-3" long.

Now use this piece of key stock you bent to drive in the slot OPPOSITE the piece you show in your picture that is broken off.

This is essentially a curved punch to drive out the piece you are frustrated with. Once the piece is pushed out an inch, remove you homemade tool with a vice gripe clamped on and tap with a light hammer.

Then clamp the vice grip on the original piece and tap in out.

Then, and only then, with the end cap come off.

 

[bigbenkubota]

BigBen, the part I put in red....did you, or the tractor shop, get the little square piece of metal unwrapped from the end of the cyl? If that retainer is not removed, trying to unscrew the end piece will not happen.

Once again, that retainer is simply a piece of key stock that is wrapped around the end of the cyl that goes in a groove to lock the end cap in place. That key stock had a little hook (bend) on the end so you know when it's in place and to remove it when servicing the cyl. In your picture the end/hook has been broken off.

You could weld something on the end of the broken off piece to get a better grip. If you have no access to that, you could get a piece of key stock. They are available in 12" lengths at most farm or good hardware stores. I would guess it's 1/4" or close. It just needs to fit in the slot, dimension is not critical.

You could actually use something round and bend it the same way. It's just a punch!

Take a piece of 2" or 3" pvc pipe, or anything else you have to use as a form. Put the pvc in your vice. Clamp the piece of key stock to the pvc with a vicegrips. Begin to wrap the key stock around the PVC. You just want to get a bend started.

The cut the key stock to about 2"-3" long.

Now use this piece of key stock you bent to drive in the slot OPPOSITE the piece you show in your picture that is broken off.

This is essentially a curved punch to drive out the piece you are frustrated with. Once the piece is pushed out an inch, remove you homemade tool with a vice gripe clamped on and tap with a light hammer.

Then clamp the vice grip on the original piece and tap in out.

Then, and only then, with the end cap come off.

Thanks for that detailed explanation - I have not approached it the way that you described. I tried pulling on the butt end of the retainer ring, but with not much to grab onto and no leverage couldn't get it to move. I tried using a punch on the butt end to see if it would move at all and it would not.

If I understand correctly, this can only rotate one direction (counter-clockwise based on my picture). It did not appear that there is any room to use a punch on the nose end of the retainer ring to drive the butt end out. And if I did get a curved punch in there with the ring rotating, wouldn't the butt end of the ring start to hit the 'side' of the punch?

Any chance someone has some pictures once this is apart? I thought (and would have expected the shop to correct me) that when you rotated the gland the key stock retainer ring would also spin out. If there is a hook in the ring (and this hook fits into a indent in the gland), then doesn't the retainer ring and gland have to rotate together until the ring has been fully backed out?

It sounds like the way you describe it that once the retainer ring is removed the gland just come right out without needed to use the spanner wrench?

I apologize for my confusion - I've been there many times that once something is pulled apart it all becomes clear, but until you get there you can easily make mistakes thinking you know how it comes apart.

 

[rbargeron]

If you are looking at buying a whole new cylinder, it would be much cheaper to alter the old one.

Have a good machine shop look at it with the idea of machining an access groove to get the old ring out and then designing a new retaining collar for putting it back together after the rod is straightened.

Where in upstate NY? Anywhere near Albany?

 

[DMC]

How is it going with the crowd cylinder?

I just rebuilt by swing cylinder, and two stabilizer cylinders on my 4690. I can give you some useful advice.

This cylinder design sucks, but it is what we have to work with. All tractor or machine manufacturers that use cylinders would do well to look at how Case and John Deere make their cylinders, and copy their design.

Let me know if you still need to tear that cylinder down.

Just for shits and giggles why don't you turn that ram knuckle around 180* and re-attach it and see it it will straiten itself out. If its not leaking I kind of hate for you to tear it down, as you would be doing yourself a disservice not to put a complete overhaul kit in it if you do.

I have subscribed to this thread, so if you respond I should get a notification immediately.