Another grapple question

   / Another grapple question #1  

deelowe

Bronze Member
Joined
May 21, 2021
Messages
68
Location
West Georgia
Tractor
Kubota Mx5400
Just got my grapple hooked up. When testing it, I noticed the hydraulic pump whines when the grapple is fully closed. If I bump it open a little, it goes away. I assume this is due to pressure from the grapple.

3rd function is wr long. Grapple is mtl rg-7.

Is this normal? Do I need to make sure not to do this when using it?
 
   / Another grapple question #2  
Might be hitting the relief valve? Perhaps your valve is out of adjustment and letting some fluid by when you think it is at neutral?
 
   / Another grapple question
  • Thread Starter
#3  
I’m guessing it’s the relief. I wouldn’t know for sure. How do I check?
 
   / Another grapple question #4  
You'd probably need to get a pressure gage into the lines so you can find out where the relief pressure is set and then do your grapple thing and see what it reads. If you don't have any of that, it will cost you a bit of moola and time to set up, and you may need to try it in a few places to figure it out.
 
   / Another grapple question #5  
Possibly check your tractor hyd. fluid level after installing the new grapple?
 
   / Another grapple question #6  
This is really strange because once your grapple closes and you release the button/lever, pressure in the grapple should be isolated. Three points have a feedback linkage so it’s possible to misadjust them so the hydraulics will continue to pump at the end of stroke if the link is misadjusted. A grapple will not have a feedback link. Shut off is that - isolated. Doesn’t make sense. Never have had that with mine but all 3 have been Kubota 3rd function.
 
   / Another grapple question
  • Thread Starter
#7  
This is really strange because once your grapple closes and you release the button/lever, pressure in the grapple should be isolated. Three points have a feedback linkage so it’s possible to misadjust them so the hydraulics will continue to pump at the end of stroke if the link is misadjusted. A grapple will not have a feedback link. Shut off is that - isolated. Doesn’t make sense. Never have had that with mine but all 3 have been Kubota 3rd function.
Would it happen if the power beyond hoses were reversed? Wr long shows it both ways in their instructions and I may have them backwards.
 
   / Another grapple question #8  
With your pump whining when the grapple is closed it is certain that your valve is still "on" applying pressure even though the grapple is already closed. That CAN be OK in cases where you may want to "squeeze something." But that squeezing must be under your control, not happening just sitting there !! So you have a rather urgent need to find out why your control valve is still calling for pressure when you have released it and ar no longer intending to "squeeze." Hopefully it is just an adjustment in your third function valve / controls. I would go so far as to say you should not operate the grapple very much at all until you get this solved. If you don't you will eventually do damage to your hydraulic pump.
 
   / Another grapple question
  • Thread Starter
#9  
Solenoid is cutting off when I release the switch. I can hear it click. Could it be something else? What about the power beyond? Should I try reversing the 3rd function hoses?
 

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