Hydraulic Quick Coupler Problem.

[EE_Bota]

I have been known to ramble, so let me tell what I think is happening:

The hydraulic QC nipple poppet has a weaker spring than the poppet spring on the female body. When the two mate, the poppet tips collide, as they should. The collision of the two poppet tips is supposed to open both poppets. But the system acts as if one of the poppets is not opening.

Today upon close examination:
When I hold a coupler set in my hand, I can look in each end and see the position of the poppet shaft. As I press the two parts together, I see that the nipple poppet does all the moving, and the female poppet, which has the stronger spring does not move (it CAN move, if I press it hard with my finger). I was surprised that there was nothing to limit the travel of the nipple poppet, so instead of being sure that both poppets are open, we have a "spring war" where the nipple spring is losing.

Just to drive me crazier, this setup acts like a check valve. When fluid is flowing out of the nipple, it can hydraulically actuate the poppet on the female end, and force it open. When fluid is flowing from the female end, the fluid reinforces the seal!

Has anyone else ever seen this?


Optional reading for background:
Last night:
Symptoms: After changing the three couplers on my BX2200, no hydraulic function worked correctly, except things on priority flow such as the power steering, PTO, and hydrostat set.

The lift would not function. The Loader would not function correctly. So I hooked the loader hoses up as if the loader was disconnected, so only the lift was in the circuit. The lift would move up slowly, with the rpm's low, but I could hear the system relieving. Increasing the rpm resulted in a click, or quiet thud, and the lift would stop.

After turning off the tractor, relieving the pressure, I restarted it, and felt the coupler for heat. It was far hotter than the surrounding piping. I removed the coupler. I started the tractor at low rpms, and the oil flow rate looked adequate, but I popped the throttle once...big mistake. Oil everywhere. Well, it was probably less than a quart total, but it was the distribution of that quart that was startling.

I examined the coupler closely for debris, but I found none. I could blow air through it, but not as freely as I would have thought. But, I figure a human blowing on a coupler is nothing compared to a hydraulic pump.

After working the system a bit more, I heard a click, and the lift started working properly again. So, I hooked the loader back into the circuit, and again no lift. So, I took the power beyond coupler off. Started the tractor, and sure enough, P pressure was in fact going through the loader valve, and returning out of the PB port of the loader valve as it should. Put the PB quick connect back on. Started and let it idle, and checked for heat...sure enough, that coupler was getting hot. Played a bit longer, and hear a click, and then the lift worked again.

OK, so the power beyond circuit was open, so I could run the tractor to test the loader out. I decided to take it up and put the tractor away in it's shed while the PB was flowing freely. But before I turned it off, I noted that the loader strains a bit going down. Think about that. The entire loader weight pushing down, and still the hydraulics strain lowering the bucket.

It sounds like the tank line is not open...the tank line coupler is still bad.

 

[kennyd]

Sounds like cheap or mis-matches couplers to me:confused2:

 

[EE_Bota]

kennyd, do you happen to have a favorite brand of coupler?

 

[kennyd]

kennyd, do you happen to have a favorite brand of coupler?

My only experience is with the Parker/Pioneer QD's, that's what came with my tractor and I have stuck with them for everything else I have added/changed. Never had a bad one-so I stick with whats works.

 

[EE_Bota]

My tractor now has new Safeway ISO-B couplers, which I bought from Surplus Center.

The problem couplers were bought from Discount Hydraulic Hose. In the attached picture, you can see how they decided to solve their own problem. They extruded their poppet seal rubber out. Obviously, once uncoupled, they would not re-couple because the extruded rubber would not allow the nipple to insert into the coupler far enough. The lack of re-couple is irrelevant to me, since these are now trash, and will never be used again.

The extruded poppet seals means that my original thoughts about what the problem was is now confirmed. If you look closely at the pic attached, you can see the extruded rubber.

 

[kennyd]

Did DHH help you out at all I hope?

 

[oldnslo]

To answer your question of " has any one else seen this" the answer is yes. We had two Fords and a Silver Lemon AKA White. The 5,000 Ford and SL had ball type QD's while the 5600 Ford had Poppet style. 99% of these would interchange but once in a while one would not and do exactly what you say they will do.

Preferred brands are Pioneer/Parker, Aeroquip, Safeway, Snaptite.

I try and stay away from unknown off brands.

Roy

 

[EE_Bota]

Did DHH help you out at all I hope?

No. I got a reply around a week ago that said their staff were looking into the problem.
They have a 30 day return policy, and I bought them in December in case my others started leaking. About two weeks ago, they did start leaking, so I did the swap.

My couplers are outside the return period, and I don't feel like I am owed anything. By the same token, I did not feel upon discovering the situation that I should just keep quiet about it. Fellow TBN folks have better things to do that change out inferior couplings, and some would be very much harmed if their tractor hydraulics were to get ruined by a situation like this.

To be clear, in case someone doesn't put it together from my rambling initial post: This situation is like you removed your loader, but did not connect your "loop" and were dead heading the pump. Sure..I was very careful, and monitored the situation against all harm, but if a member did the same thing, and did not monitor, I would feel horrible about knowing and not saying.

Thanks for the reading and the help fellows.

Sometimes I see posts that claim hydraulic problems, and the replies say "disconnect the couplers and reconnect them" and see if the problem goes away. Often it does. I have always been a bit suspicious about that and now I am wondering if folks are connecting them right, but they simply will not flow. The reason is this: If one of the poppets has no meaningful fixed mechanical limit, and the other poppet is under pressure and therefore resists opening, a member could connect them correctly, yet they still would not flow.

 

[J_J]

A test gage with QC's could determine whether fluid was blocked, or flowing by observing the pressure reading on the gage. .

 

[bdsandefur]

I am trying to operate a wood splitter with my Kubota M7040D, but when I let off the hydraulic lever on the splitter, the hydaulics seem to not be happy. I was told by another farmer friend to use one outlet to power the splitter and return oil to resevoir, but not through the other outlet. Where do I return oil on this tractor. The splitter works fine on my JD 4320.