Hydraulic Part Identification / function help

snowman · Oct 22, 2020

I have this hydraulic unit, only marking is marathon motor and vesco cap. I think it's a vesco vari pak, but that just describes the tank, not the functional parts.

Anyway, looking at the relief valve/valve block/gauge, can anyone explain what the two ports coming out the top are for? The one on the left seems to be outlet, the one on the right possibly return to tank? I am guessing that only because it's situated on the same side as the relief valve. There don't seem to be any identifying numbers.

Right now I am having trouble getting unit to work when connected to a center closed valve (it stalls after moving cylinder to maximum position, so I'm assuming relief valve isn't opening?). It circulates fine without load attached. I have backed out the relief valve thinking it might have been wound in too tight.

I am also not getting any pressure reading on the gauge, even when it stalls the motor.

snowman · Oct 22, 2020

I think that's just the pump compensator valve, and I need a directional valve with built in pressure relief. Does open center/closed center matter in terms of the directional valve? I just want to make a cylinder move in and out.

metalmagpie · Oct 22, 2020

I'm guessing the pump is in the tank.

I suggest you remove that valve and take it apart. It shouldn't be difficult or complicated. Once apart, you will likely understand how it works and what it does, or at least find some numbers you can look up.

metalmagpie

snowman · Oct 22, 2020

metalmagpie said:
I'm guessing the pump is in the tank.

I suggest you remove that valve and take it apart. It shouldn't be difficult or complicated. Once apart, you will likely understand how it works and what it does, or at least find some numbers you can look up.

metalmagpie

Yes, pump is in the tank.

I will probably end up doing that...because it seems that even if it is a compensator, which I no longer think it is, it should still display a pressure on the gauge, and it should also kick the oil out, unless the pressure is set higher than the pump is capable providing.

i hate hydraulics

snowman · Oct 22, 2020

Finally backed the relief all the way out, hoping it would come out, which it didn't. Anyway, when I did that, I was able to start the pump, but it sounds like it's cavitating. Upon starting, I can screw the relief back in until about 250 PSI, then it stalls.

So I need to take the whole thing apart and see if it has enough oil in it (I think it's a submerged pump, but I'm not sure). If not that, hope that installing an open center valve will provide enough flow to keep the pump primed, and not cavitating...and if that doesn't work, probably replace the pump...or the motor, who knows.

boslab · Oct 22, 2020

Looks a bypass valve
Mark

Ziggy2 · Oct 22, 2020

snowman said:
Finally backed the relief all the way out, hoping it would come out, which it didn't. Anyway, when I did that, I was able to start the pump, but it sounds like it's cavitating. Upon starting, I can screw the relief back in until about 250 PSI, then it stalls.

So I need to take the whole thing apart and see if it has enough oil in it (I think it's a submerged pump, but I'm not sure). If not that, hope that installing an open center valve will provide enough flow to keep the pump primed, and not cavitating...and if that doesn't work, probably replace the pump...or the motor, who knows.

Is the pump/motor direction correct?

snowman · Oct 22, 2020

Ziggy2 said:
Is the pump/motor direction correct?

Yes. 110 volt, but already checked that.

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idacal · Oct 22, 2020

not a lot of pictures of the hosing but I don't think they would use a closed circuit system (that's a variable flow pump very expensive) on a basic power power pack you probably need an open center valve and some way for the oil to return to tank
that may have been built to run a hydraulic motor one direction, turn it on, run your motor turn it off. jmo need an open center valve and a dump port in the tank but more pictures of the full unit would help
I wouldn't think you want it hitting the relief except for momentarily.

snowman · Oct 22, 2020

idacal said:
not a lot of pictures of the hosing but I don't think they would use a closed circuit system (that's a variable flow pump very expensive) on a basic power power pack you probably need an open center valve and some way for the oil to return to tank
that may have been built to run a hydraulic motor one direction, turn it on, run your motor turn it off. jmo need an open center valve and a dump port in the tank but more pictures of the full unit would help
I wouldn't think you want it hitting the relief except for momentarily.

Thank you...that is what I thought, but don’t have enough experience with hydraulics to really know for sure.

Is it reasonable to think that the 250 psi relief valve problem where it won’t go above that, is likely to go away once I have an open center valve that allows the pump to fully prime?

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idacal · Oct 22, 2020

I tried to find an easy to watch youtube that makes sense. Probably look up woodsplitter hydraulic systems. they would make the most sense. Personally I cant follow written diagrams, Have to se it work. Basicly an open center system is a pump that flows to a valve a relief on the pressure side in the system then back to the tank. When the valve is kicked it sends the oil to the cylinder while the oil on the other side of the cylinder runs back through the valve into the filter then into the tank. I think its a 4 way 3 position valve is what is needed. Dont know if this makes sense

true temper · Oct 23, 2020

You need an open center control valve, some valves can be converter from open center to closed center by changing a plug.
Tell us more what you are trying to do, and more photos of plumbing.
You should be able to get way more than 250PSI before stalling the motor.
You have a sight gauge to check oil level.
Return from open center should go through the oil filter.

snowman · Oct 23, 2020

It's going in to a closed center valve with only one solenoid, so opening it up would never retract the cylinder.

I think I've got a small pile of hydraulic stuff at my other shop. That's my biggest detractor on stuff like this, is I don't have the parts to just "play".

develope · Feb 4, 2021

Hi everybody, just joined this forum. hoping someone as info regarding a closed Hydrualic system, I've just got hold of a power pack and cylinders, plus two monoblock 4way controllers, I've already got a power pack on my other machinery, but this new one is different in it's makeup, I've tried to find something on it on the internet, the best thing I've found is something called a Closed System, there is no return pipe going directly to the tank as normally found, the ports to tank goes to a block just under the motor, the power port is at the side of it, the back to tank port as a tee fitting coming from it, why this is I have no idea, the pressure releaf valve is at the side of this block. I've never worked with a closed system before, so if anybody as any info, regarding this type of system, my old power pack goes up to 350 bar 5000psi pressure, the new one only goes up to 100 bar around 1400 psi, all the cylinders are 4" 100mm bore with 2" / 50mm shaft. if the tonnage is not good, I may have to link it to my old power pack, as I have a lot of ports to connect it to adding another foot pedal. Thanks for reading my post

trevj · Feb 6, 2021

You could do a lot worse than to track down a Hydraulics text book and read through it.

And learn to not try to piggyback your posts in an unrelated thread.

Snowman, stick a frikken hex key into that port cap and pull it off. My nickel worth of free advice, is that it is in the same circuit as the other outlet, so as to be able to add another like the first, nothing fancier than that. The pressure relief will be a simple spring closed, pop-off valve, with the adjustment increasing or decreasing the spring pressure, allowing the fluid to return to the tank.

Like the other fellas have said, you likely need an open circuit style control valve, so as to allow flow around the circuit while the cylinder is not moving. The good news is about every tractor out there uses open circuit hydraulics, so those are about the cheapest valves to be got, other than cobbling up plumbing parts (bad idea, not suitable for pressures!).

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Hydraulic Part Identification / function help

snowman

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metalmagpie

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boslab

Titanium

Ziggy2

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idacal

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