Ark 508 loader, more questions

[chevyaddict83 39]

So, i ended up rebuilding curl pistons, worked great. Now, having lift issues. If i pull on the lift lever slightly, i still get the arms to go up. If i pull all the way back, the whole thing drops. If i leave it raised and fill the bucket, it stays up and dumps fine. Is it something in the control valve? Maybe an adjustment?

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[Madcat 9]

Sounds like the control valve is going into the float position when you pull it back. Maybe you got the valve reversed or the hoses reversed.

[chevyaddict83 39]

I didnt think i had a float position. It was working like it should, then it started happening

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[boovuc 1,090]

If you have the original Ark manufacturing control valve(s), you have a float on it. It does sound like the valve/lines in & out are reversed.

This is what the original control valve looks like.

 

 

 

[MalMac 1,331]

I agree with what was said about lines reversed. Wow that would be dangerous having the arms just drop. When you pull the control lever all the way back, do you feel it snap or clunk on the very last of the travel stroke of the lever. If so your going into float.

[chevyaddict83 39]

Now, my first question is, if the lines are reversed, wouldn't the up down function be going backwards? Or just pressure in the opposite direction, like more dwonforce instead of up? It was working good, then it got fussy

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[boovuc 1,090]

It may not be just that simple but if you have the original control valve the Ark came with, it has the float feature when pushed full forward. If you didn't change the valve in any way or the inlet/outlets it may be nothing more than air in the lines. After you rebuilt the cylinders and added oil, it is recommended to slowly raise and slowly lower the arms then do like wise to the bucket doing full motion slowly. Do this several times to both systems and check your oil reservoir adding if/when needed. (Make sure your oil isn't full of micro bubbles after using it a while).

If your certain you have all the air out of the lines and you don't have the reservoir overfilled, I concede to the hydro gurus for more possible explanations short of debris hanging up in the system. 

[brandonozz 168]

I have a Ark that is doing something similar but not when I pull the lift lever all the way back.  My loader drops slightly when I pull the lift lever ever so slightly.  An axample would be when a load is lifted half way off the ground and held there.  Then raise the load higher.  If I pull the handle 1/16" the load will actually slowly drop.  If I continue to pull the handle a bit further the fluid flow will "catch" and the load will raise and act as it should.

My guess in both your case and mine is spool valve wear.  Hopefully someone who has taken one apart can chime in as to their thoughts.

[shorts 182]

It's the nature of the beast for this hydraulic system to drop a bit when the load lever is moved after being in the center position.  these hydraulic systems use a fixed displacement pump that bypasses or builds no pressure until it is diverted thru the valve to do work, consequently you get a little drop when you try to lift a load.  The newer no drift systems use a constant pressure variable displacement pump along with usually pilot operated valves, so their is always pressure on the system in the valves even when they are in the neutral position so that when you move the valve the hydraulics don't have to wait to sense the need for pressure to lift the load.

[pfrederi 17,741]

It's the nature of the beast for this hydraulic system to drop a bit when the load lever is moved after being in the center position.  these hydraulic systems use a fixed displacement pump that bypasses or builds no pressure until it is diverted thru the valve to do work, consequently you get a little drop when you try to lift a load.  The newer no drift systems use a constant pressure variable displacement pump along with usually pilot operated valves, so their is always pressure on the system in the valves even when they are in the neutral position so that when you move the valve the hydraulics don't have to wait to sense the need for pressure to lift the load.

 

 

What Shorts said....I had noticed th same issue with my D200 and her ARC loader.  Went to the hydro repair place and he told me it was normal. Just move it a bit faster he said

[chevyaddict83 39]

I lnow the drop you guys are talking about. Mines different. Ill try and post a video

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[brandonozz 168]

It's the nature of the beast for this hydraulic system to drop a bit when the load lever is moved after being in the center position.  these hydraulic systems use a fixed displacement pump that bypasses or builds no pressure until it is diverted thru the valve to do work, consequently you get a little drop when you try to lift a load.  The newer no drift systems use a constant pressure variable displacement pump along with usually pilot operated valves, so their is always pressure on the system in the valves even when they are in the neutral position so that when you move the valve the hydraulics don't have to wait to sense the need for pressure to lift the load.

 

Didn't think about the lack of pressure in the system causing a little "slack" when the handle is first pulled.  Makes sense now. 

Thanks for the insight!