843 unwanted arm float

[HanSolo]

So I've noticed that when I'm back-dragging with the lift arms raised and bucket edge down, I'm getting some floating on the lift cylinders. I don't have the arm peddle pressed full forward for float. When I do use the float function, it behaves as it should. Also, with the lift arms all the way down and the bucket tilted down, the arms do not float but remain stiff in the full down position. I do not have any fluid leaking from the seals on the lift cylinders but maybe something internal starting to fail?

 

[antfarmer2]

Try lowering the bucket then tilt

 

[Tazza]

Try lowering the bucket then tilt

Is it float or could it be pin/bushing wear?

 

[HanSolo]

Try lowering the bucket then tilt

I shouldn't have to do that. The operator should be able to back-drag with the arms raised and the bucket edge down and near vertical. That way all four tires make ground contact. When operating the machine in this manner, the lift cylinders on the arms shouldn't give way to grade changes or bumps.

 

[HanSolo]

I shouldn't have to do that. The operator should be able to back-drag with the arms raised and the bucket edge down and near vertical. That way all four tires make ground contact. When operating the machine in this manner, the lift cylinders on the arms shouldn't give way to grade changes or bumps.

Tazza - I do have wear on the bucket end of the tilt cylinder and that is something I'll fix eventually. This is much more like the arm cylinders "floating" when they should be static. It does not happen with the arm cylinders fully retracted - only at a bit of elevation. Those cylinders do leak down slowly but no fluid is coming out of the seals. Another odd thing is if I shut the machine down with the bucket pointed down, the arms raised and all four wheels on the ground - the arms leaking down will raise the front wheels of the machine without tilting back the bucket.

 

[antfarmer2]

Tazza - I do have wear on the bucket end of the tilt cylinder and that is something I'll fix eventually. This is much more like the arm cylinders "floating" when they should be static. It does not happen with the arm cylinders fully retracted - only at a bit of elevation. Those cylinders do leak down slowly but no fluid is coming out of the seals. Another odd thing is if I shut the machine down with the bucket pointed down, the arms raised and all four wheels on the ground - the arms leaking down will raise the front wheels of the machine without tilting back the bucket.

Seals in the cylinder might be leaking by................aux hydro off?

 

[HanSolo]

Seals in the cylinder might be leaking by................aux hydro off?

Yes, aux hydraulics definitely off. So there can be cross leakage within the hydraulic ram due to poor seals and that would cause the ram to not lock into position. Correct?

 

[antfarmer2]

Yes, aux hydraulics definitely off. So there can be cross leakage within the hydraulic ram due to poor seals and that would cause the ram to not lock into position. Correct?

Yes they can leak by the seals lift up the bucket turn it off and see if it falls

 

[antfarmer2]

Yes they can leak by the seals lift up the bucket turn it off and see if it falls

There are some valves in there that can give problems but don't know that cat others will be along soon

 

[Tazza]

There are some valves in there that can give problems but don't know that cat others will be along soon

Can you extend the ram and watch the sticks, or get a helper to watch as you back drag? see if they move inward without pushing the pedal?
It's not common, but the nut that holds the piston to the end of the rod can back off and cause issues like this. My dad has a 453 that i was re-doing the bobtach, the rod had a mind of it's own when i was setting it up to weld a new eye on it. I took the cylinder apart and yep, the bolt was quite a few turns from being tight.
You would be amazed at how something you never though was possible can actually be the cause. A member had a slow moving ram, turned out a rag was used and somehow ended up getting stuck into a fitting causing a restriction.

 

[HanSolo]

Can you extend the ram and watch the sticks, or get a helper to watch as you back drag? see if they move inward without pushing the pedal?
It's not common, but the nut that holds the piston to the end of the rod can back off and cause issues like this. My dad has a 453 that i was re-doing the bobtach, the rod had a mind of it's own when i was setting it up to weld a new eye on it. I took the cylinder apart and yep, the bolt was quite a few turns from being tight.
You would be amazed at how something you never though was possible can actually be the cause. A member had a slow moving ram, turned out a rag was used and somehow ended up getting stuck into a fitting causing a restriction.

As old as this machine is, it would probably be smart to go ahead and re-seal all three cylinders. While I've got the tilt ram out I can take it to a machine shop and have them bore and sleeve the boss. If it exhibits the same floating action after those repairs - there's something else wrong.

 

[antfarmer2]

As old as this machine is, it would probably be smart to go ahead and re-seal all three cylinders. While I've got the tilt ram out I can take it to a machine shop and have them bore and sleeve the boss. If it exhibits the same floating action after those repairs - there's something else wrong.

If your hydro oil is in good shape good time to clean your chaincase out and refill with your hydro fluid and treat your hydro to new

 

[Tazza]

If your hydro oil is in good shape good time to clean your chaincase out and refill with your hydro fluid and treat your hydro to new

I like the idea of machining the ram eyes out and installing new bushings. I don't know why they aren't standard on all rams...

 

[HanSolo]

I like the idea of machining the ram eyes out and installing new bushings. I don't know why they aren't standard on all rams...

I remember seeing a thread where someone had rigged a jig on the Bobtach to do that bore. The Bobcat parts diagram shows a bushing for this model but if it ever existed - it's long since wollowed out. Previous owners weren't much into lubing.

 

[TriHonu]

I remember seeing a thread where someone had rigged a jig on the Bobtach to do that bore. The Bobcat parts diagram shows a bushing for this model but if it ever existed - it's long since wollowed out. Previous owners weren't much into lubing.

The thread was probably this thread: Line Boring my Quicktach Bores where Tazza and I have done this repair.

 

[Tazza]

The thread was probably this thread: Line Boring my Quicktach Bores where Tazza and I have done this repair.

I actually worked on the machine i did this to about 2 weeks ago now. The pins are just as tight as when i did them.