Fix for Pressure Bound Hydraulic Couplers ?

[bdhsfz6]

All the Kubota dealers I've dealt with over the years seem to prefer flat faced hyd. couplers on the 3rd function valves and FEL mounted implements they sell. IMO, flat faced couplers have some advantages. They don't load up with debris, don't leak much oil during connection, are easily cleaned with a rag and don't require protector caps.



They are expensive though and are prone to pressure binding. The pressure must be completely relieved on both sides. For my Kubotas, Relieving the pressure on the tractor side requires lowering the FEL to the ground, shutting down the tractor and working the FEL valve in all four directions while holding the 3rd function valve open. I sometimes have to do this multiple times.

My implements are more of a challenge. Even though the pressure is relieved after disconnecting, it always builds again due to temperature changes, cylinder bleed down or movement of the implement itself. Most of the time, I have to loosen one or both of the hose fittings to bleed the pressure off when connecting again. To me, this is a PIA and defeats the purpose of the leak free coupler design.

Am I missing something here? Do other users of flat faced couplers have similar problems?

I've been thinking of switching to the Pioneer style with pressure check on both sides:



Before I spend considerable $$ to convert two tractors and several implements, I'd like to know if they will be any better. I'd appreciate the opinion of others here.

There is always the option of going to the Pioneer style with no pressure check on the male side like those used on rear remotes. The oil loss is considerable with this type though.

I'm also considering adding a tee in the implement hoses with a valve such as this one to bleed off pressure:

1/4 NPT 5 GPM Prince WFC-4 In-Line Flow Control | Prince Mfg | Brands | www.surpluscenter.com

Thanks in advance for any suggestions.

 

[Fallon]

You only need to turn off the tractor & actuate the 3rd function each way, not the whole loader. That usually is enough for me. Plan B is a wrench & cracking the QDs on the the impliment. Disconecting an imiments when it's hot & connecting it when it's cold helps, but isn't always possible.

I've thought about switching over to connect under pressure QDs, but they are even more expensive than flat face from what I see. Usually have a threaded fitting of some kind to give you a mechanical advantage to push the connectors together overcoming any pressure, from what I've seen. I don't think the AG style will be any better than flat face. I couldn't plug my TnT cylinders in when an impliment was hanging on the 3pt. Had to set it down, relieving pressure & they finally hooked up. Decent OEM Kubota AG style QDs there

 

[bdhsfz6]

You only need to turn off the tractor & actuate the 3rd function each way, not the whole loader. That usually is enough for me. Plan B is a wrench & cracking the QDs on the the impliment. Disconecting an imiments when it's hot & connecting it when it's cold helps, but isn't always possible.

I've thought about switching over to connect under pressure QDs, but they are even more expensive than flat face from what I see. Usually have a threaded fitting of some kind to give you a mechanical advantage to push the connectors together overcoming any pressure, from what I've seen. I don't think the AG style will be any better than flat face. I couldn't plug my TnT cylinders in when an impliment was hanging on the 3pt. Had to set it down, relieving pressure & they finally hooked up. Decent OEM Kubota AG style QDs there

Not sure why but relieving the pressure on just the 3rd function valve doesn't do it on either of my Kubotas. Both have W&R Long 3rd function valves.

I read a post in another forum about someone solving the problem by shutting off the tractor and holding the 3rd function valve open with a rubber band on the switch. Might try that one. Still, the implement side is more of a PIA than the tractor.

 

[dstig1]

I have a longstanding issue with this on my current tractor and my previous one on the third function. Also flat face couplers. I can do anything i want regarding releasing the pressure and if i am lucky I can connect one of the two couplers. I made a pressure reliever out of a couple of pipe fittings and one each flat face coupler (open to air). If I cannot get a coupler to connect, i use this to let out some pressure. I also often put a quick grip clamp around the fitting when i can get it partially together then cycle the lever to keep releasing the pressure bit by bit and alternating by tightening the clamp. Eventually it will make it home, but this is a major PITA for trying to hook up the grapple as it adds a good 15 min just making the hydraulic connections sometimes. I even spent extra money on the flat face "connect under pressure" couplings. No effect i could see!

 

[mopardude318]

I've tried those connect under pressure flat face couplers available from Discount Hydraulics. I just used them actually last week. The truth is, is that I haven't noticed anything different, it was still difficult to connect, and I had to relieve the pressure from third function with the tractor off. Another thing, maybe I got a bad set from Discount Hydraulics, but they leaked right from the get go. I noticed they said "made in china" on the side...Maybe that has something to do with the leaking problem? I was a certainly disappointed once they constantly seeped while in use, since I paid $90 bucks to my door for the set.

4HTF4-P-SET | Set of 1/2" Connect-Under-Pressure ISO 16028 Quick Disconnects

 

[4570Man]

I find them a little better. You can hit the male coupling against the loader and it will depress the button and let fluid squirt out. Sometimes it'll take like that. Other times you'll need a punch and hit the female side too. I've found that if you equalise the implement ( my 3rd function is 12 volt so shut off the tractor, turn the key back on, and cycle the button several times) it'll usually go back on with minor issues unless there's been a temperature increase since it was disconnected.

 

[bcp]

One man's fix:

http://www.tractorbynet.com/forums/build-yourself/305952-flat-face-hyd-coupling-pressure.html

Bruce

 

[lennyzx11]

I put a male and female on each implement and on the tractor.
By hooking the implements hoses together when off the tractor, I haven't had to fight that connection anymore.
I used to just leave the tractor side loose but after using the aforementioned practice of smacking the ball of the fitting to relieve pressure, I find that the fitting will leak fluid on the garage floor overnight.
So now those two lines also get looped together also which gives an advantage of keeping the internals of the QDs clean.

 

[Wagtail]

I'm glad that the OP included the names/terminology of the couplers he has and is considering (different countries = different words). I've not seen these 'flat' versions myself.

I do have the "pioneer" type that he is considering and the result will be the same. I, too, have to relieve the pressure (shut down the engine and move the joystick in all four planes + the 3rd function button in two planes) to connect/disconnect. I do not lose any hydraulic fluid using this method.

It took many attempts and too many swear-words until a thread on TBN twigged me to this fact.

 

[mopardude318]

I might break down and try these made by Holmbury, I have their standard 'HQ' couplers on my auger, which appear to be real nice.

Eliminate pressure in hydraulic systems with flat-face couplings - YouTube