Third Function Cylinder not Holding Position

[irsmun]

I have had 3rd function hydraulics installed for sometime now. I don't usually use my machine as I have an employee who is an excellent operator. When operating today I noticed that when I open my grapple and let go of the switch (its electric) that the cylinder releases and starts going down. When I clamp it and let go it relaxes when I release the switch. Isn't it supposed to hold in the position it stopped in? Why is the fluid in the cylinder equalizing the pressure when the switch is not applied? Could I have a faulty solenoid. I think I have a 4 way 3 position solenoid valve with a spring to center.

Any help would be appreciated. It makes operation aggravating.

 

[ptsg]

Sounds like a bad cylinder seals

 

[irsmun]

Hmm. I will have to check that. I don't remember seeing any fluid leaking around the cylinder.

 

[ptsg]

Sorry, I meant the internal seals of the piston could be leaking from one side of the piston, to the other.

 

[irsmun]

Is there a way to check for that without opening up the cylinder?

 

[irsmun]

Ok, so I had the cylinder repaired. It now bites and stays down...but when I raise to full open it slowly goes down. I was under the impression that my electric solenoid valve would be closed when no power was applied. That means it should hold its position wherever it stops. Why is the fluid slowly returning to the tank? Do I have a problem with my valve?

 

[J_J]

Solenoid spools can leak also.

Install a needle valve in the cyl line and see if it still retracts.

 

[trktrman]

Solenoid spools can leak also.

Install a needle valve in the cyl line and see if it still retracts.

Agreed! I've learned a lot from your posts J_J

 

[Budweiser John]

To accomplish a third function circuit for my grapple I installed an electric diverter on the bucket curl circuit.
I initially had a similar problem with the grapple clamp mode not holding the load tightly but through trial and error figured out the diverter button must be held down for several seconds to allow the full hydrolac pressure to build up in the clamping cylinder. For compress able loads such as lose brush it's often necessary to activate the cylinder additional times as the load compresses in transit.

 

[irsmun]

Can you help me better understand your suggestion? Put a needle valve where? On the line to the open function?