Yes, that's where we disagree.I think that there can be fluid interchange between the cylinders if the weight changes on one of the cylinders. But I do agree that it cannot bleed back into the reservoir. To me free flow between, just between the cylinders, explains why the pump only pumps to one cylinder and not both.
Howard, once the Hydac valve on the curbside leg is de-energized and it closes, there can be no movement of fluid to either cylinder. It can't receive fluid from the pump, and it can't allow fluid to move back and forth between the two cylinders....
If that comment is directed to me, then go back and read your very first post and your description of a problem that you are having and "any help is appreciated" comment. So if your above comment is directed to me, that is exactly what I'm trying to do.
And if you use "Reply with Quote" when you respond, there will be no guessing as to who the comment is directed towards.
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Yes, that's where we disagree.
I agree. There is nothing preventing fluid from moving between left and right landing gear because there is no valve in between. The fluid will move to equalize the force on the two LGs.
You are the one that brought up a scenario about "no load on the cylinders in Post number 57, and that is when I made the post that you have quoted above
And as a final comment, I'm done with this thread. Obviously, trying to help someone is not always the best idea. I hope you get it solved, but I'm out of here.....I've wasted too much time on it already.
Scott'n'Wendy
Senior Member
I agree. As long as there are no check valves in there the pressures will balance between the cylinders. I believe the rear legs work in the same fashion on the same side. Do they not?
Yes. It’s basically a three legged stool. Front landing gear, left rear, right rear. Fluid moves between the two jacks at each position to equalize the force in the two jacks tied together in each of the three positions with the imaginary leg centered between the jacks.
I hate to beat a dead horse, but that diagram is incorrect. In that diagram the back four legs are plumbed together for the retract, which is not correct. This schematic from Lippert that shows the correct plumbing:
. FWIW, it shows the retract and extend lines between the front two legs would allow for free exchange of fluid. And it shows the rear/middle legs on each side are independent for both extend and retract.
If I’m not mistaken all retract lines are plumbed together via the retract manifold (no valves on it)
Howard, I just went out and looked at mine....there are only two of the black lines coming from the rear. What that means is that all 4 legs back there....the 2 mids and the 2 rears are plumbed together and return on one line. The other black line is for the hydraulic slide rooms, which are also tied together and return up front on one line.....That accounts for the two lines coming from the rear and the absence of a third line.
Scott'n'Wendy
Senior Member
Could be just different a different version? Different system on different years or maybe different depending on the weight of the trailer?
A couple years ago, the valve for the passenger side jacks got stuck open. Meant that anytime we activate any hydraulic function, those jacks would go down. Drop the front jacks, the rear right side jacks would go down. Open the slides, the right side jacks would go down. Making a long story short, the dealer that fixed this for us recommended we replace all 4 valves. Not wanting to spend money on those valves that were working, I opted to only have them replace the one that was not working. Fast forward about 2 years later and we're getting a very slight creeping down on the drivers side. I'm suspecting that valve is not performing correctly. So something to consider. . . . If you have it all torn apart, maybe you want to just go ahead and replace all 4 valves. (BTW, I carry a spare valve with me now.)
On a side note, we also had the popping issue that was about 95% resolved with the Lippert fork oil recommendation. I don't think this'll solve your valve problem but again, as long as you're in there doing work on it, why not? Here's the info from Lippert:
View attachment Lippert Fork Oil.pdf
On a side note, we also had the popping issue that was about 95% resolved with the Lippert fork oil recommendation. I don't think this'll solve your valve problem but again, as long as you're in there doing work on it, why not? Here's the info from Lippert:
View attachment Lippert Fork Oil.pdf
That's very likely Scott. Mine is a 2018 and the Lippert picture I posted up was a revision that was done in 2019. I think the picture that Howard Hoopy posted up was like a 2021 revision.
Well, you can color me completely confused because I remember when I repaired the rear leveling leg hydraulic line, it went from the passenger side rear to the driver's side rear. So that would mean that diagram from Lippert is WRONG! But I also now don't understand how the left legs and right legs can retract independently if they're plumbed in series like it shows. Gaaaaahhhh, I give up.
Well, you can color me completely confused because I remember when I repaired the rear leveling leg hydraulic line, it went from the passenger side rear to the driver's side rear. So that would mean that diagram from Lippert is WRONG! But I also now don't understand how the left legs and right legs can retract independently if they're plumbed in series like it shows. Gaaaaahhhh, I give up.
All retract lines are plumbed together. During retract the pump is pumping fluid into the retract side but the jack can't retract unless the valve on the extend side is open, because the fluid can't flow out of the jack on the extend side. All of the valving is on the extend side. None on the retract side. Hope that helps.
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Well, you can color me completely confused because I remember when I repaired the rear leveling leg hydraulic line, it went from the passenger side rear to the driver's side rear. So that would mean that diagram from Lippert is WRONG! But I also now don't understand how the left legs and right legs can retract independently if they're plumbed in series like it shows. Gaaaaahhhh, I give up.
LOL....no reason to give up, it's very simple. The retract function even with all of them hooked together, ALSO requires the Hydac valve to be energized/open, for whatever function that you are trying to perform, otherwise when the pump reverses (CW rotation of the pump) and tries to pump the fluid the other way for retraction, the fluid on the top of the RAM has no where to go and it would lock the fluid in the top of the cylinder on the top of the RAM. When the Hydac, opens, then the fluid can flow back to the pump through the orange lines. See, wasn't that easy
Think of it like this....when you are extending you are using the Orange lines to drive the ram out/down. When you are retracting, the pump rotation changes and the pressure from the pump is now the black lines.....but no fluid can move unless a Hydac is open.
I'm headed out to mow....check in later....
Okay, I think I got it. Even though there is pressure to the retract side of the cylinder, there is no where for the pressure to go on one side because the extend side of the cylinder still has pressure.
Yes because the valve is closed on the extend side and the fluid has nowhere to go. To actually retract, the valve on the extend side has to open to let the fluid flow out of the top of the cylinder so fluid can flow into the bottom of the cylinder and retract.
That's correct....and by the Hydac opening for that particular function also, the fluid on the top of the RAM no has a way to relieve and flow back to the pump.
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