hydraulics on Grapple slow

[JYD]

Hi All!!
Question
I have a JD 4320 with root grapple. Sometimes the grapple arm is very slow to close and other times it operaters fine.

Any idea why sometimes it is so slow to close???

Your help is appreciated

JYD

 

[kennyd]

Are you operating the grapple through a diverter or are you using the 3rd SCV?
Does the engine bog down when its operating slow like it's straining to move the cylinder?

 

[JYD]

Yes I have a 3rd SCV installed in the front. Engine does not bog at all. I have no problem with the FEL or PTO

 

[MrJimi]

Is your fluid level full ?
Jim

 

[JYD]

I will check the fluid level. The Tractor is at my cabin in northern Wisconsin, I will be back up there in 2 weeks. I am hoping it is lower on fluid as that would be a easy fix.

I will let you know

If fluid ok, then what?

 

[kennyd]

Yes I have a 3rd SCV installed in the front. Engine does not bog at all. I have no problem with the FEL or PTO

If the engine was bogging, I would have suspected a malfunctioning QD, but since it's not, I will guess the seals in the cylinder are bad and leaking internally.

 

[MrJimi]

I will check the fluid level. The Tractor is at my cabin in northern Wisconsin, I will be back up there in 2 weeks. I am hoping it is lower on fluid as that would be a easy fix.

I will let you know

If fluid ok, then what?

Make sure that you bleed your system of all air with full extensions of all hydraulics both ways.
all the way extended and all the way retracted of ALL hydraulic functions, That's what Andy at Wayne County Hydraulics told me Shh
Jim

 

[Wayne County Hose]

Sounds like you have summer seals inside your cylinders. Summer good, summer not. Sometimes the piston seals do this depending on what style they are. They roll over and don't seal, then they will roll back and be okay for a while. When it does this, try rocking the lever back and forth but not too fast. See what happens.

 

[hayden]

When the grapple is slow, are you also operating the loader or any other hydraulic implement? I'm not familiar with how the Deere is set up, but if you are operating something else at the same time you will be sharing the available hydraulic flow between the two functions rather than dedicating it to one. This will slow down both functions. Also, if you have something in series after the grapple then it can be creating backpressure which will slow down the grapple.

I'd suggest trying to zero in on exactly what you are doing when the grapple is slow, and how it's different from when it's fast. I've found it's real easy to be operating two things without really being conscious of it.

 

[jinman]

Hi All!!
Question
I have a JD 4320 with root grapple. Sometimes the grapple arm is very slow to close and other times it operaters fine.

Any idea why sometimes it is so slow to close???

Your help is appreciated

JYD

Did you build the grapple hydraulics, or was it done by your dealer? Is it possible the dealer installed a small orifice or metering valve in line and it is being clogged? As kennyd noted, you should hear the tractor load up some when you try to operate the grapple.

I don't think it's an internal seal, because this normally causes the grapple to droop even when you release the SCV control valve. The grapple would droop or have no holding power.

Is it only slow in one direction? Closing? Can you swap the lines to see if the problem direction changes? That would tell you lots.

 

[ddivinia]

What RPM are you running the engine?

I have a JD 4720 with a JD grapple bucket. I am using the 3rd SCV. It is never really that quick closing, but I am not waiting on it too much. I use the same grapple on my JD 5525 which has a much higher capacity hydraulic system and it runs about the same.

The time I see it is really slower is if the engine RPMs are down or if I have a lot of additional load on the tractor. Like moving, turning, raising and clamping at the same time.

D.

 

[3RRL]

I think Jim is onto something.
With the variation between fast and slow operation "sometimes", leads me to believe you have an obstruction like a torn "O" ring or something or a piece of debris that "sometimes" interferes with the flow.
You might want to check your valve to see if that's the case.