Third Function / Grapple Operation

[gunny0628]

I just hooked up my grapple after the winter (here in Florida) to move some debris. I haven't had it hooked up since before the tractor leak issue I posted some time ago (maybe 10 months ago). Anyways, I hooked up the grapple as normal, and went to pick up a pile of oak branches that were trimmed - the movements are fine except for closing the grapple. Once it is closed, either part way, all the way, with debris in it or nothing in it at all - the top portion of the grapple can be opened easily. I don't remember this being the case. The problem is, when I pick up debris I can somewhat grab it, but not forcefully. It won't clamp down like it used to.

Any ideas? I haven't messed with any of this since last year. And now unfortunately I am being told the third function only had a year warranty and the grapple is pretty much useless now.

I have a RK 55HST Cab and the third function was installed when I purchased the tractor and grapple. I have the 60" Granite Grapple.

I've talked to RK mobile repair and he is looking to see if he has any spare parts.

 

[DonRybak]

Hey gunny, that's a bummer. I guess I missed the post about leak but was it hydraulic? Is it possible that the fluid level is low? The pressure to open and close the grapple are strictly grapple or 3rd function valve related. An issue with the tractor's hydraulic pump would affect the FEL movement too. Almost sounds as if there is an air pocket in the grapple. That's my guess anyway............

 

[gunny0628]

Hey Don

The FEL seems to be working fine. And for the most part the grapple works as it should movement-wise. I can open and close it, tilt and go up and down. The problem is that the grapple won’t stay shut and won’t shut with any force if there is any debris like tree branches in it.

Once I get it closed you can easily lift the top “jaw” of the grapple open.

This never used to be the case.

I looked at the the third function yesterday that was installed at the front of the tractor and everything looks to be in order. No leaks, etc. I checked the dipstick at the rear of the tractor and it is showing full.

 

[gunny0628]

I just removed both quick disconnects/connects and found one of them to be 'not as rigid'. I took it apart with a pair of snap ring pliers and cleaned them out and now it is working beautifully.

 

[gunny0628]

well, not fixed. i thought it was the QD and unfortunately i am back to square one. i am going to replace the QD on that side and see if that fixes it with a new one, instead of a tinkered one. Also, when I took the QD off there was a ton of bubbles coming up through the hose. Could that be from a cylinder????

 

[gunny0628]

new QD installed (both male and female) and everything seems functional for now. I'll update if there seems to be any other problems, but I'm guessing this was the culprit.

 

[agjones]

Good troubleshooting. Hope you are done.

 

[DonRybak]

Great job Gunny. Hopefully it was just a bad QD connector allowing air to enter the system THere shouild be no bubbles. I don't believe that you have a cylinder issue. If it was a cylinder then you would have an issue with the bucket. The cylinders have no clue as to if they are applying pressure to a bucket or a grapple. They just put of the pressure. The 3rd function valve then determines how the pressure is distributed

 

[ovrszd]

The valve only manages flow, not pressure. Pressure is determined by the pump and pressure relief valve.

 

[DonRybak]

Ovrszd, not to start a bickering contest I have to agree and disagree. The 3rd function valve does control flow direction but if gunny has the bucket installed and there is enough pressure to lift the tractor when the bucket is on the ground and curled down but lacks pressure to close the grapple when installed how can the pump or relief valve be the culprit? Using random numbers what if the 3rd function valve is designed to flow 3 gallons per minute though the closing port but due to internal failure is only partially opening allowing just 2 quarts per minute that would drastically change the pressure.