We have 3 newer dumptrucks with 3 pup (pony) trailers. When the drivers un-hook and leave their trailers for the day, the wet lines get hot and the pressures go up enough to make it impossible to couple the disconnects. You have to release the pressure by pushing in the nipple on the female coupler. This results in a small puddle of hydraulic on a city street. I was just wondering if anyone else had this problem and what they did about it?
What type of couplers are you using? I looked at the Stucchi webstie and it said that standard wing type wet line couplers could be made up under pressure.
Been using Parker 60 series The line for the hoist is 1" and the high lift gate line is 1/2". I helped the driver pop the pressure on the lift gate and could hear the gate drop a bit when I did it. Haven't had the problem before the new trailers arived last year.
It sounds like you have a problem with the control valve that works your lift gate has excessive internal leakage causing the lines to become pressurized. I think you have a problem with the new trailers. Holding valves on the lift gate cylinders would fix this problem. But, I'm sure you don't want to have to deal with changing the component design of your new trailers, then again, you may want to call up the trailer builder and give him an earfull. If your content in being able to "hook up" with a bit of lift gate drop, the Parker 60 series coupler is your problem. It's a general purpose coupler. I doesn't compensate for pressure on the lines. You might want to consider changing to a "connect under pressure" quick couple. I don't know what the Parker coupler would be, but here's a link for the Stucchi coupler. http://www.stucchiusa.com/PRODUCT SERIES/APM.html
Hot weather- can't couple wetlines: Now, that's a link I can connect to... lol Good find, ATCO... :thumbsup OCR
I have the same problem with my 4 way bucket and grappler on my skid steer. I've tried the coupling that ATCO suggests with some success, but it has its limitations. My solution has been to cycle the attachment a few times just prior to disconnecting to warm the oil in the attachment. You could do this with the trailers, but I imagine it would take quite a bit of time.
Yeah, the couplers ATCO posted would help but they are expensive. Our guys drag them down the road on occasion and they have to be replaced. The problem isn't warming up the oil- it's the fact that the oil is getting hot in the hoses coming out of the tounge causing expansion and creating pressure.
We use the 6100 series Parker Quick Couplers. http://www.hydraulichouse.com/TOC/Hydraulic_quick_coupling.cfm Your right they are expensive though. Especially if they drag them around. The cheapest option would be to go to the hardware store and buy some new paint cans. Put an oil diaper in the bottom and pop the ball into it. Put the lid on and carry it in the truck. Solves the oil on the street problem.
The more I think about it, I believe you might be right. You're saying you take a trailer out in the morning, drop it off, then come back later to pick it up, and have a problem making the connection to the lift gate line. Correct? There would be a small amount of oil in the line, and, if the cylinder is installed in a way that would leave the cylinder extended even just a bit, there would be some oil in the cylinder. As the oil warmed up from the days heat, the oil would expand, creating pressure, and even lift the gate ever so slightly. Pop the coupler and "thunk"...gate comes down. If all this is correct, I wonder if installing a small nitrogen charged accumulator in the line would help? In theory, it would absorb the pressure allowing you to connect couplers. Can't say for sure it would work, just a thought.
I understand what the problem is, I have the same issue here. The oil expands when it is warmed and creates the pressure. What I was suggesting is to cycle the hydraulics before detaching to warm the oil in the trailer, so it is parked with warm oil and will actually create a vacuum when it cools. It works for me every time, but as I mentioned, it takes a while for the dump trailers to cycle. Might not be practical. By the way, my bucket develops so much pressure you can't depress the center of the coupling, I have to crack the fittings. The hose will stand out straight if you hold it a ways from the end.
That's a neat trick Steve. By adding warm oil to the cylinders, then allowing time for cooling, the oil will contract as it cools, taking away the pressure, and allowing you to re-connect the couplers. I'm wondering, though, if the mutiple drivers for RobVG could remember to do this each time. Forget one time and it's back to pressure on the coupler. :Banghead I haven't had to deal with this, it's an interesting problem.
I see what you mean now Steve. ATCO, you understand the problem exactly. An accumulator would work but how much would it cost? I'll talk to our Parker rep and see if there is some kind of inline "bumper" I could use. I realized today that our trailers are now parked on fresh black top. This probably added to the problem. I was trying to think why our old trailers don't do this. I think it's because the rams on the old trailers leek.
If I was to take a wild guess...I'd guess the way the cylinders are installed. The 1/2" line would have some oil in it that could cause the problem, but I'd guess the cylinders are installed in such a way that when the lift gate is all the way down it still doesn't have the cylinders fully retracted. Which, depending how far they are extended, could be a cosiderable quantity of oil remaining in the cylinders to expand. It's enough expansion to raise your liftgate a bit, that takes pressure.
Well, I should wait untill after I look at it but the cylinders for the liftgates are vented- just one hydraulic line behind the piston. The weight of the gate brings it back down. The line for the liftgate and the line for the hoist are always full of fluid- fluid is trapped when they're disconnected. Your idea of talking to the manufacturer is a good one.
Yes, I understand, you have single acting cylinders. They only have a hose going to one end of the cylinder. Here's what I'm getting at; fluid is pumped into the cylinder and begins to fill the cavity behind piston. The volume of oil is increasing inside the cylinder, so this forces the piston to extend the cylinder out until it reaches the gland and bottoms out. Now, you release the gate lever, this allows the oil to discharge from the cylinders and go back to tank. The weight of the gate forces the piston back into the cylinder. But...does it force the piston all the way back in until it bottoms out? That's what I'm getting at. If the piston doesn't bottom out, then there's going to be some quantity of oil in there to expand.
Hmmm... Yeah but... The cylinders and the hoses are covered by a metal "hood". They don't get any direct sunlight. On the otherhand, the gate hose and the hoist hose coming out of the tounge are in the sun and are black. I think the sorce of the pressure is the hoses capped with quick couplers?
I agree with all above. I haven't really encountered this problem, just trying to noodle through the thermal dynamics of it. We can assert it's a real problem by what Steve has experienced with his attachments. Are you having the same problem with the 1" line on the hoist cylinder?
10-4
Ahhhhh! Mystery of mystery's as to why your new ones do this and the old ones don't. Let's try a different solution. Typical wing style wetline couplers. They thread together so they can be connected with pressure on the lines. Parker and others make these style couplers as well. http://www.stucchiusa.com/PRODUCT SERIES/Wing.html
I'll check 'em out tomorrow. This problem will shortly disappear- until next summer
LoL, you're probably right. This is the type of couplers that are typically used on wet lines for lowboys and such. Again, I don't work with this type of stuff, I was kinda hoping someone with experience with this type of problem on trailer wet line connections would jump in here.
2 things that might work. 1. lift the gate with pry bar an inch or so when hooking up. this should reduce any pressure buildup and allow the QC to open on the trailer side. 2. install a "T" and a valve, open to outside air, in line. open just before hookup to release pressure. Just make sure it is closed before operating lift gate or you will have a mess to clean up. Make sure valve is rated for the pressure you are using.
what if you put a valve tween the 2 lines to equalize the pressure?
Stucchi couplers are something i would NEVER put on anything i own. we use them on excavator lines at work and are always having trouble with them leaking and the guts coming apart and then they get stuck together very badly... just my .02
trainwreck, I think I said "Parker and others make these style couplers as well". I'm not promoting Stucchi. Just trying to help RobVG with his problem. If you have a problem with Stucchi, then I suggest you have it out with them personally and not on this forum. This forum is a haven for reference, not a personal soapbox. BTW, are you using a hyd hammer and having problems with the couplers?
we are not using a hammer. most of the time we run a clam shell bucket setup. something like pictured in the link below. http://www.cwsindustries.com/products/excavator-powerclam-grapples.aspx# well i am trying to give him my opinon of those coulpers. so is it not ok to voice our opinon???????????
Would it be any help to paint the exposed hoses white to reduce the heat absorbed from the sun?:beatsme
How about light-colored abrasion covers, might work better than painting them?
some places around here have a hose cover made from what looks like fire hose that is light colored, that might work well.
I didn't say that, please voice your opinion. I'm just pointing out that the premise of your post was that there is nothing good about Stucchi couplers. You said you would never put them on anything you own, and that you have used them on excavators and "always" have problems with them. I didn't intend for you to keep your opinion to yourself, on the contrary, I'm suggesting that from the problems you describe having that you contact Stucchi, I'm sure they would be interested to hear this. We have installed both Parker and Stucchi on the attachments we sell, just depends on which company desires to give us the best price at the moment. I don't recall a customer calling and reporting the same difficulties that you have experienced. I mentioned using a hammer because that's one sure way to destroy these type couplers. The shock of the oil while hammering makes them come apart inside just like you described, sounds like your not doing that though. As long as you've found a coupler that is working for ya, life is good.
the owner of the company i work for ike the Stucchi setup so we still use them and relace them often. our local dealer says they have a new model or redesin or something like that. so maybe all our trouble will be a thig of the past. we run them mostly on 300 and 400 size excavators. i have put 3 sets of them on this summer.
Well, I went to the Parker store today and was told this is a common problem- especailly with attachments. They recommend (and sell) Stucchi couplers and demonstrated a set hooked up to a hand pump. At 4000 psi, they were easy to put together. They were the threaded sleeve type. Dirt could be a problem. I'd love to give them a try but at $450 per truck and trailer (two lines) I'll find another solution. The idea of a light colored hose covering is definetly worth a try. I'm not sure if the heat is also coming from the frame and there is exposed hose in the "A" section of the tounge. Still worth a try though- cheap if it works.
Wouldn't that be sweet! I have a feeling your problems may very well be related to the work you do and attachments that you have to use. Of course, I have no idea about your actual operation, but take the clam bucket. Being what it is, I assume the clam is pretty much constantly being opened and closed, the auxilliary circuit is constantly starting and stopping oil flow through the lines and couplers. Unlike an ex with a thumb that only gets used to occasionally grab something, then it takes a rest while the bucket does some work. The constant cycling of the clam may be working the life out of the couplers. Hmmm. Let's hope you guys find a workable solution. Have you tried to, maybe, get lucky and find some on E-bay? :cool2
Was this the type of couplers you tried RobVG? http://www.discounthydraulichose.com/4100_Series_Wet_Line_Couplings_p/4100-set.htm
No, they weren't quite like those. I have a quote on my desk and can post the part monday.
OK bro. That is a pretty hefty price tag you mentioned for couplers. You might want to look at the wing style couplers. They are pretty much a standard type of coupling for lowboys and hyd dumps that have wetlines. And it's claimed that they can be coupled under pressure. Again, I don't necessarily work with this kind of stuff, I was hoping we'd get a truck driver that uses wetlines in here to tell us how well these type of couplers work. They seem to be more affordable than what you were quoted.
Hmm, I took another look at those and 'per set', those are cheaper than the Parker 60 series.
http://www.discounthydraulichose.com/4100_Series_Wet_Line_Couplings_p/4100-set.htm we use those on all 12 of our lowboy trailers andthe drivers seem to really like them. i am not a driver so i can not tell you anymore then that.
trainwreck, what size wetlines are on your lowboys? Do your couplers come straight out the back of the trucks? On our dumptrucks, the male couplers point strait down from under the box. Our pups have a 1" single wire line that's really stiff. You have to wrestle the hose to get it to couple. I think there might be a problem with the "wingnut" style and cross threading .
Rob, I installed those style of couplers that trainwreck posted on our static burst machine, the guys could not get the original couplers to couple when the hoses laid out in the hot sun, or after the machine had run. We have not had any problems with cross threading which, if it was a problem, I am sure my guys could have figured out a way to do it. The reason we went with the wingnut style is because we were told that is what is used on wet lines. I had some issues with the guys overtightening the fittings and had to replace some o rings in the fittings, but after I instructed them that the hammer is used to loosen and not tighten we have not had any more problems. As far as dirt- they make dust caps that you can use when the fittings are uncoupled. Also they make rebuild kits, so once you buy it, you can service it. Evidently we impressed the manufacturer of our static burst machine because they came out and are in the process of using them on new machines.
Thanks for the info Red Bank. Fall has arrived in the NW in a big way. 39° this morning I'm going to bookmark this thread for next summer. Oh, and those guys with the hammer, don't lend them one of your good screwdrivers...
i dont know what size lines are on the lowboy trailers, the hoses are very long so they are easy to move around.