Quickconnect hydraulic coupler issue (and not from too much pressure)

   #1  

Bullwinkle123

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Kubota MX5400HST, Z724XKW-3-54
I have third function hydraulics on my Kubota for my grapple. Last year I didn't have any issues with it. This year is another matter. In the first use of the spring I couldn't get the couplers to mate. FIgured it was pressure, took the usual measures, no lock. Tried again the next day when the tractor was cooler and managed to connect.

Then last week I needed to attach it again. One connect works fine. The other though, what an incredible pain. I wrestled with that thing on three different days with no luck. All nipples on all the male connectors can easily be depressed with nothing more than a bit of oil drool coming out. So it isn't pressure. The ball bearings seem to retract fine. The pair in this case is such that the male is mounted on the loader, and I'm trying to slide the female on. It just _will not_ close that last 1/16 to 1/8 inch.

Or wouldn't. Yesterday I finally forced the issue, used a clamp and a wrench as a pressure point for the clamp and finally mated the two pieces. It made a little "thwup" noise, as if the o-ring and hydraulic fluid in residence were telling me something. Now mated, I note that the connection is ever so slightly jiggly compared to the other connect pair. Anyway, all things worked, no fluid leaked, but darned if I can figure out why it was so resistent to connecting. I ran my finger around all the surfaces involved, no irregularities. Just a mystery.

This is a new system, just over a year old. Just wondering if anybody has any thoughts here.

Btw, in all the attempts where I didn't force it, it would get coupled enough to release oil from the male nipple, just not enough to seat and latch.

Stumped. Maybe it will be better next time having finally given it no option this time, no idea, but in general it's been uncooperative this year after no issues last year.
 
   #2  

Michael In Tennessee

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Grapples are problematic as the weight of the lid exerts pressure on the cylinders. You need to remove that pressure.

This is how I connect my Grapple:

I store my grapple half open with the ends of top and bottom tines on the ground. I do not connect the grapple hoses together. Each is separately capped.
I mechanically attach the grapple (SSQA).
Then, I relieve pressure on the tractor side by making sure power is available to the 3rd function and cycling both buttons. Obviously with the tractor engine off.
I have the grapple basically level at this point and about 2 ft off the ground. Since the grapple cylinders are pulling the cylinders one direction, the opposite side should be pulling a slight vacuum and the hose to that side should just plug in.
Then, I uncurl the grapple and push the top tines into the ground. This removes any pressure on that side of the cylinder and the remaining hose just plugs in without issue.

Works every time. I have a short bottom tine EA wicked 60. On a long bottom tine grapple, I think you can do the same, but you might have to get creative. The idea being to somehow rotate the lid in the open direction to relieve pressure on the cylinders.
 
   #3  

ericm979

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I store the grapple with the lids closed and a tee connected to the quick connects. The other end of the tee has a valve with a cap. When I put the grapple on I let out any pressure that has built up due to temperature rise (or suction due to temperature fall), disconnect the tee and plug into the tractor. Works great.
 
   #4  

Michael In Tennessee

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I store the grapple with the lids closed and a tee connected to the quick connects. The other end of the tee has a valve with a cap. When I put the grapple on I let out any pressure that has built up due to temperature rise (or suction due to temperature fall), disconnect the tee and plug into the tractor. Works great.
Well gee, come up with a way simpler than mine. :)

Other than the $50 in extra parts, great idea.

Since I have a short bottom tine root grapple, I cannot store it closed unless its leaning up against something. It just falls over. Then, its a real pain to mechanically attach. BTDT.
 
  
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#5  
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Bullwinkle123

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Thanks all, but as I said in my post, there's NO PRESSURE in the lines. So unless zero pressure is the problem, that isn't it. Some oil does dribble out on every coupling attempt but it's all passive gravity-fed leakage. One of the couplings just does not want to mate and I can't figure out why.
 
   #6  

daman1

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Use said the male connector did you try the female connector? Does that easily push in? If you have pressure on one side they won't go
 
  
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Bullwinkle123

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All male connectors had no pressure. The female from the grapple to the mail on the tractor wouldn't connect, the male from the grapple would connect. I don't *think* it would be the case that one grapple hose would have pressure when the other didn't, though I suppose they're seperated by a cylinder they could. Is that possible?

I did every kind of pressure reduction technique I could think of, which is how the males were all devoid of pressure.
 
  
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Bullwinkle123

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Use said the male connector did you try the female connector? Does that easily push in? If you have pressure on one side they won't go
One pair of connectors mated fine, one pair just refused until forced with the clamp.
 
   #9  

Michael In Tennessee

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All male connectors had no pressure. The female from the grapple to the mail on the tractor wouldn't connect, the male from the grapple would connect. I don't *think* it would be the case that one grapple hose would have pressure when the other didn't, though I suppose they're seperated by a cylinder they could. Is that possible?
Yes, very possible and if you read my post, it is normal for me.

Was your grapple lid closed?
I did every kind of pressure reduction technique I could think of, which is how the males were all devoid of pressure.
Well, since you didn't check the female side, you didn't.
 

i7win7

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I have a male & female on tractor and implements. Prevents connecting backwards. When dropping attachment connect both hoses together. Also don't fully retract cylinder, if you have to relieve pressure on male connector piston can move slightly reducing pressure on female connector.
 
 
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