Hydraulics won't hold

[J_J]

The odd thing, is that both outriggers are doing the same thing. On the BH relief, it should be set equal to the main PRV. If he is pumping fluid into the cyl's, and the relief never activates, the fluid is going somewhere. You are right, there is no relief in a static situation. The leak is in the cyl's or the spool, or both.

 

[arcamm]

If it helps, the cylinder is 16" eye to eye, 1" rod and 2.5" cylinder. Two cylinders, two valves doing the same thing. I'll check to see if they off center.

 

[J_J]

If you put a gage in the rod end of the hose, you can watch the pressure equalize if the piston seals are bad.

 

[wdchyd]

arcamm,

If it turns out to be the control valves, be prepared to do a complete clean and rinse out of the reservoir tank (including rag clean in bottom).......if multiple valves are worn it almost always points to contaminated hyd oil grinding away at spool tolerances.....as least you have a gresen valve bank and replacement sections can be had to repair this situation......

Best to test and troubleshoot like you are doing to eliminate doubt....:thumbsup:

 

[glastron23]

AKKAMAAN... wondered when you were going to jump on this one.... totally agree that the valve bank is your problem and not the packings. this is a going to be REALLY GOOD discussion.... Jim

 

[AKKAMAAN]

AKKAMAAN... wondered when you were going to jump on this one.... totally agree that the valve bank is your problem and not the packings. this is a going to be REALLY GOOD discussion.... Jim

Thanks Jim!
Cylinder drift is to many times misunderstood. Piston seal many times in fault but, but in retract mode like this there is always an additional problems due to the cylinder rod displaced volume.

Now we now a little more about what volume that are leaking per minut...

Great to see these pictures.....seems like cylinders are bleeding down 4-8" on the rod....that will make 3-6 cubic inch per minute...

If piston seal is bad, pressure intensification will boost pressure to 6.25 times higher than work pressure that lift. If it takes 500psi to lift up excavator, drift pressure will be 3125psi....and an eventual work port relief will open...

This will happen even with a good piston seal, but at a much slower cylinder drift, which would be considered normal...

 

[arcamm]

I need a flash course in hydraulics to get me in the game.

One other thing I observered, on the left side outrigger, there were a couple of times when I was trying to get the machine up on the riggers that when I pushed the lever to lower the outrigger, it would come up instead of going down. I would return to neutral (and actualy go in the oposite direction because I thought I was moving the lever the wrong way), then go back and the ram would go in the right direction.

 

[AKKAMAAN]

I need a flash course in hydraulics to get me in the game.

One other thing I observered, on the left side outrigger, there were a couple of times when I was trying to get the machine up on the riggers that when I pushed the lever to lower the outrigger, it would come up instead of going down. I would return to neutral (and actualy go in the oposite direction because I thought I was moving the lever the wrong way), then go back and the ram would go in the right direction.

My picture is pointing out (fingers) the position for the work port relief valves that could cause the bleed down...try to find the ones that are connected to the outriggers, I cant tell if there is and valve cartridges in them slots or not....
Please post a detailed picture of both sides of the valve stack??
The valve should be on the same side as the lever, if you push the lever (spool) to lower outriggers/extend cylinders....

About the other observation you had...

....when I pushed the lever to lower the outrigger, it would come up instead....

If you can't repeat it, "it never happened"...LOL....IMO it can be ignored for now...

 

[arcamm]

Here's some more pictures. Does this help?

 

[wdchyd]

It looks like the valve castings are machined for WPR's but are plugged.......

No WPR's......