3rd function valve failure.

[Rabun]

Hello From Oregon

The cylinder on my grapple stopped working. I believe the problem is that the my 3rd function valve is sending fluid to both sides of the cylinder. I know this because I disconnected both hoses at the cylinder and activated the switch. When I did this fluid came out of both hose at the same time. The majority of the flow is on the side of the cylinder that being actuated but the other hose has a flow that is about 15-25% that of the hose with the majority of the flow. The opposite happens when I press the switch in the other direction.

So these are the things I've done so far, to no avail:

1. Replaces the seals on the piston in the cylinder.
2. Test the switch, works fine.
3. Confirm that the spool moves inside the valve block in both directions in order of the switch.
4. Scratched my head, still doesn't work. Ha

So my guess is that the spool is not sitting in the right position in relation to the ports in the valve block and as a result, I'm getting flow in both directions. Or the hydraulic pressure is moving the spool and allowing fluid flow in the two directions at the same time. As if the induction on on the valve is not working correctly...

Yanmar 424
Construction attachments grapple
International Fluid power of America valve kit I got from Idaho Implements

Any thoughts?

 

[KWentling]

Not surprised you are seeing flow out the return side of the valve because you have opened the whole hydraulic system return up to atmosphere. Are you sure the grapple is not locked up mechanically? Put a gauge on the hoses and see what pressure your getting to the grapple.

 

[MinnesotaEric]

Have you disconnected and reconnected all of the quick disconnects between the valve and the grapple? For example, on my loader there are two sets of valves so that I can also remove the loader, as well as at the SSQA.

 

[Rabun]

Not surprised you are seeing flow out the return side of the valve because you have opened the whole hydraulic system return up to atmosphere. Are you sure the grapple is not locked up mechanically? Put a gauge on the hoses and see what pressure your getting to the grapple.

I guess I don't understand why there would be flow on the return side? Would that be from residual preassure on the lines back feeding?

Don't think the grapple is locked up. I was able to move the pistol with air after replacing the pistol seals. The grapple moves if the cylinder is removed.

No I haven't put gauges on the hoses. I guess I should try that, but all other hydraulic systems work 3 pt, FEL, & Top & tilt.

 

[Rabun]

Have you disconnected and reconnected all of the quick disconnects between the valve and the grapple? For example, on my loader there are two sets of valves so that I can also remove the loader, as well as at the SSQA.

No I haven't tried this, but I'll give it a try. The FEL works just fine and the grapple is downstream of the FEL so can you explain how this might help? Do I have SSQA (skid steer quick attach, right?) on my tractor? Thanks

 

[MinnesotaEric]

No I haven't tried this, but I'll give it a try. The FEL works just fine and the grapple is downstream of the FEL so can you explain how this might help? Do I have SSQA (skid steer quick attach, right?) on my tractor? Thanks

If one of the quick disconnected isn't locked on, it will not flow fluid creating the symptoms you have.

SSQA ia skid steer quick attach. This is the one or more levers that work two pins to attach things to your loader.

 

[KWentling]

I guess I don't understand why there would be flow on the return side? Would that be from residual preassure on the lines back feeding?

Don't think the grapple is locked up. I was able to move the pistol with air after replacing the pistol seals. The grapple moves if the cylinder is removed.

No I haven't put gauges on the hoses. I guess I should try that, but all other hydraulic systems work 3 pt, FEL, & Top & tilt.

Any flow that isn't going through that valve, such as priority steering flow, returns through a common path that likely has a filter. Oil takes the path of least resistance, which is the return port on the valve you have disconnected. It's possible to have a bad male end on a quick disconnect also, stopping or restricting flow.

 

[LD1]

Pretty much what others said. The side of the valve that isnt being actuated (the one flowing 15-25%) is probably feeding the loader valve, which in turn feeds the 3PH. Thats back pressure and oil likes the path of least resistance.

You probably wasted your time/money rebuilding the cylinder.

Check the disconnects. (the ones you plug the grapple directly into when hooking it up).

If that dont work, time for a pressure gauge.