580C backhoe hydraulic drift only under load

   / 580C backhoe hydraulic drift only under load #1  

tduncklee

New member
Joined
Apr 2, 2012
Messages
8
Location
columbia, tn
Tractor
GC2410 and 580C
Today I had to replace the main hydraulic supply hose under the loader valve. A while later (maybe an hour or so) the backhoe hydraulics were slow and weak. The loader is fine. Fast and strong.

When operating a control, say raising the boom with a load in the bucket, the dipper drifts down and the swing drifts to the left. The drift is quite fast. If I release the boom control, the dipper and swing drift stops. I imagine I got some crud in the system but would like some advice as to where I should start.

Thanks for any advice!
TD
 
   / 580C backhoe hydraulic drift only under load #2  
TD,
Have you cycled all of the BH several times after swapping out the hose. You may just have some air trapped in the system or possibly some crud that may flush out with use.

Not familiar with the 580C controls so can't really give you any other ideas on where to start.
 
   / 580C backhoe hydraulic drift only under load #3  
You could check to see if the dipper spool or swing spool is bypassing fluid by removing the work port hose for the dipper or swing work ports and operate another spool .

Since a cyl spool is supposed to lock the cyl, if a cyl leaks fluid with no lever operation, then you have work spools.

Perhaps the spools spring centering is not return to center/neutral. There is a set of springs in the can on the bottom of the valve . Check for correct torque on the nut holding the springs.
 
   / 580C backhoe hydraulic drift only under load
  • Thread Starter
#4  
oldnslo,
Trapped air was my first thought. I ran it for quite some time and cycled everything. no luck.

J_J,
I am absolutely positive the dipper and swing spools are bypassing fluid. I tilted the machine with the stabilizers so it leaned to the right (sitting in backhoe position). The swing drift is absolutely to the left. Not sure if it's a "drift" if the swing is uphill though. So, when putting a load on the system by curling the bucket all the way in or out or running the extend-a-hoe all the way in or out or raising the boom with a load, there is positive oil flow that makes it swing to the left and drop the dipper.

Since this happened suddenly, I can't imagine that two different controls would simultaneously have springs out of adjustment. I'm sure you understand what I mean when I say my hands are very familiar with the position of the levers. They are centered while this is happening.

Another symptom; I do not hear it (I guess my ears are too old...) but my son tells me he hears a "hissing" sound when operating a control that was not there before.

In studying the diagram, I don't see anything that explains the exact symptoms but then I've never had one of these apart... However, the regeneration parts seem suspect to me. If one is stuck open I wonder if that would cause these symptoms.
 

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   / 580C backhoe hydraulic drift only under load #5  
TD,
Do you have any other diagrams of this valve or a hydraulic schematic? I am having difficulty understanding how flow is controlled or directed to work ports from the diagram you attached.

oldn
 
   / 580C backhoe hydraulic drift only under load
  • Thread Starter
#6  
oldn,

I had to post it on another site since uploads are limited to 1M here. The backhoe control valve docs start on page 99 towards the end of the document.
http://absolutenet.com/tim/580Chyudraulics2.pdf

Today I pulled the Regeneration Check Valve and Regeneration Spool to check for crud causing them to stick. Although there might have been some really small stuff in the spool, cleaning and flushing did not fix the problem. :(

TD
 
   / 580C backhoe hydraulic drift only under load #7  
TD,
With the bucket full of dirt can you raise the dipper so it under load. Stop all other functions and try to feather the dipper movement to raise it even more against the load. Does it drop some before raising or hold steady until it starts to raise. Trying to confirm the load check and secondary relief are both working properly.

Is the BH still slow and weak or has the lifting force and speed returned?

Hissing sound is usually from fluid being dumped through an orifice or leak point and creates heat. If you can carefully touch the valve in several places to see what gets hot first. This would be an indication or were the leakage is which would cause the heat generation.

I will be away from internet service for a couple of days so good luck.
 
   / 580C backhoe hydraulic drift only under load
  • Thread Starter
#8  
Oldn,

New information. I don't know why I did not see this before but apparently my son, who is new to running a backhoe, forced a rock against one of the boom cylinders and bent it. It's bent/dented pretty bad so I'm thinking the piston and/or the inside wall of the cylinder has had some metal shaved off and the shavings are now in the control.

To answer your question though, I used it today to pull a bolder out of the ground and it seems stronger than I thought but the drift of the dipper and swing when using it make it hard to use. Aside from the drift of the boom due to the damaged cylinder, it does not hesitate to raise with a load and does not drop before raising.

Great tip on the hissing! I'll check that out next time I use it. Thankfully, todays bolder is all I need the backhoe for for a while. Lots of loader work still but it is working great. I'll get a new cylinder and at this point I probably should pull the control valve and tear it down. It does not look like it's that bad of a job to do.

Thanks!
TD
 
   / 580C backhoe hydraulic drift only under load #9  
TD,
I finally talked to friend of mine that worked for Case in their BH plant hydraulics division. He said if your valve is a "Case" valve and not one made by Continental the problem is a pretty simple fix.

Between the work port or auxiliary relief valves and the load check is a plug. This plug requires a special tool that is described in the service manual to remove. On these plugs are O-ring and back-up rings that extrude over time. When these seals fail it will cause the drift problem you are experiencing. He said you should probably check and replace all the seals on these plugs.

oldn
 
   / 580C backhoe hydraulic drift only under load
  • Thread Starter
#10  
oldn,

That helps a lot!!! For now, my project is finished so as soon as I get time I'll get the damaged cylinder replaced and pull the plugs. I did see the special tool in the manual so I know what you are referring to.

Thanks,
TD
 
 
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