Parker coupling issue

[rd_macgregor]

I'm having a problem with the Parker Flat-faced couplings on my grapple rake. I keep the couplings mated to keep them clean when the rake isn't mounted. Last time I went to hook up the grapple rake, it was very difficult to get the couplings on the grapple rake apart. After I did, I couldn't get them hooked up to the tractor's couplings (nor, as it turns out, back to each other). With a little experimentation and prodding, I discovered that the male fitting center plunger (valve?) seems frozen/stuck. I can depress the ring in the female fitting, but the center of the male fitting won't budge (even with some careful hammer application).
This doesn't make sense to me, since I had just separated the fittings a few minutes earlier...which means that center piece in the male fitting WAS depressed, but won't move now. What can cause this stubbornness?? Any suggestions would be welcome (replacing the fitting is my last choice).
Thanks in advance,
Bob

 

[aczlan]

Try loosening the fitting (unscrewing it) to see if it relieves a bunch of pressure. It sounds like you have pressure built up in the line that wont let go.

Aaron Z

 

[BukitCase]

You may have some bleed-through on one of your valves, allowing that coupler to be pressurized without actually moving the related valve -

One thing to try, if you haven't already - turn off the tractor, then excercise all the valve levers back and forth (especially the one associated with the fitting in question) and try to depress the "culprit" again.

IF this fitting is coming from an electrically controlled diverter valve, you'd need to have the key turned on (but not the engine running) to cycle it.

HTH... Steve

 

[J_J]

You might consider changing out the QD's to the connect under pressure type.

 

[Scooby074]

The couplings are on the impliment?

You likely have some pressure buildup in the lines. Could be just from the heat of sitting in the sun.

Use a wrench and unscrew the fittings to release pressure, youll likely blow out a bit of oil in the process.

 

[rd_macgregor]

The couplings are on the impliment?

You likely have some pressure buildup in the lines. Could be just from the heat of sitting in the sun.

Use a wrench and unscrew the fittings to release pressure, youll likely blow out a bit of oil in the process.

Thanks for all the suggestions. Yes, these are the lines on the implement, which was parked for a few months. What surprised me is that I had just uncoupled the fittings from themselves so I could hook up to the tractor-side fittings. I guess another option would be to wait for cold weather and see if that relieved the pressure.
I like JJ's suggested solution (except for the extra cost, of course). I didn't know there were such things as connect under pressure fittings; I've always been doing what Steve suggested...shutting down the tractor and moving all the levers...of course, that still wouldn't address the problem I'm having now with the implement fittings.
Thanks, again.
Bob

 

[BukitCase]

"I've always been doing what Steve suggested" -

Yeah, sorry 'bout that - skimmed your first post too fast, didn't catch that these were the IMPLEMENT QD's.

JJ's plan would work, but here's another thought -

Since you are coupling your "gazinta" into your "gazouta", this gives you a closed loop connecting both ends of your hydraulic cylinder(s) together -

Under those conditions, there is only ONE position of the cylinder rod that will give neutral pressure - and this would VARY depending on temperature when it was hooked together, as well as whether the mechanical pressure on those cylinders changed while they were deadheaded.

This is because of the displacement of the cylinder ROD. That causes a different amount of hydraulic fluid to EXIT the cylinder than the amount that ENTERS, whenever the cylinder moves (or is pushed by outside influence) - this is because (example) you have a 3" bore cylinder with a 1.5" diameter rod - so the NON rod end of the cylinder has 1.5 squared x pi surface area - the ROD end has that area MINUS .75 squared x pi for surface area.

This means that for ANY position other than the one it was at when the QD's were mated together, assuming the cylinder COULD move, there will be a significant difference in total oil volume required. Since liquids tend not to want to be compressed, ANY movement of the cylinder would cause either a vacuum or a pressure within the closed loop.

The only time this would NOT be the case is if you had a leak, either in the hoses/fittings OR the piston seal.

Add that to temperature changes, and things can get unpredictable.

One example - you park your grapple on a pallet (or ground, whatever) and couple the two hoses. Either gravity, or moving the grapple, or heat, etc, causes the two halves of the grapple to either extend or relax - now the internal pressure has changed (from none to some, so to speak)

The only way I've found that would compensate for ALL the differences that can happen during storage, assuming you DON'T want to leave your hoses open, is to take ANOTHER pair of QD's, couple them together with a TEE in between, hook a small valve to the third leg of the tee, and BLEED the tee into a coffee can or something to relieve whatever pressure/vacuum has accumulated.

This SHOULD relieve pressure differences, if that is the problem - but like JJ's solution, it ain't cheep.

Sorry for the long-windedness, I'm often told I think too much :confused2: ... Steve

 

[ishiboo]

All great suggestions.

I would NEVER press on the nipple/ball of a quick connect with my finger/etc... if there is pressure behind it you could be seriously injured.

 

[jinman]

Buy one male fitting to match your implement. When you disconnect the implement, insert the male fitting into the female fitting on the hose end. The open fitting will drain off any pressure and make reconnecting a breeze. Put a Ziploc bag over the end of the fitting if you want to catch any oil that leaks out. You also could just bungee the hose so the fitting is pointed upward and high enough that all the hyd fluid does not leak out. You only need one fitting per circuit as long as you have your hydraulic cylinder(s) in something other than maximum extension or retraction. Just a little off the hard stop is all that's needed. Male connectors are much cheaper than female connections, but a single female connection will work fine also.

I once had a FEL that I disconnected and looped the hoses. The pressure inside the hoses become so high in the Texas sun that the hose popped out of the loop and were sticking out straight. I had to loosen one fitting for the lift cylinders and one for the bucket cylinders to break the pressure lock. If your grapple rake has two hydraulic functions, you need a fitting for each function, but you only mentioned one set of hoses. That only requires one fitting as described above.

 

[J_J]

You should be able to just push the male QD poppet or ball on a hard surface and release the pressure.

If the male QD is stationary, tap it with a piece of flat metal using a rag over the QD.