Pressure testing difficulties

[J_J]

A CC valves blocks the hyd flow and causes the fluid to pass through a relief valve upstream as most solenoid valves no not have relief valve.

An open center hyd system uses a gear pump to pump fluid and the fluid is always moving.

How long has the valves been installed?

If you need solenoid valves for remotes, then select the open center valves.

If you want to read the pressure for any part of the system, install the gage in a tee in the IN port of the first valve. Then anytime you use a valve, the gage will reflect the pressure developed by that circuit.

However as in the other post about relief valve, the lowest valve relief setting will limit the pressure.

If you remove those CC valves and connect the PB hose from the FEL to the 3pt, you should be back to normal operation.

How long have you had those valves? Maybe Northern will exchange them for you.

 

[murphy1244]

JJ, please excuse my ignorance of Hydraulics but I'm wondering why bother having 3 relief valves if the lowest one will open before the others do. I am willing to learn.

 

[J_J]

You have a lot of post so you must know something.

All hyd circuits need relief valves as the fluid is almost incompressible. You don't want to stop the flow unless you want it to do work.

A gear pump, as in an open center hyd system is pumping all the time, and if you try and stop or block the flow, the pressure will build up until something burst or breaks.

Why three or 4 relief valves in the same tractor,

Every tractor using hyd needs a relief valve, and when the tractor is first made, it usually has one relief designed for the 3pt..

Then someone installs a loader and runs the flow though the FEL first. Well, that valve needs a relief.

Then some one installs a remote valve and it also has a relief.

So now you have three relief valves in the flow path.

Some people like too use the term { Master relief ] but that title will change depend on the setting of which relief.

Logically, you would set all relief valves the same.

You could set each valve to a set pressure to relieve when that hyd circuit developed pressure up to the set pressure.

Now, if the are three relief valves in the series flow path, If you activate the last valve, then the lowest relief setting upstream will activate and protect the total hyd circuit. Also, the lower pressure will limit the force developed by a cyl or motor.

If someone makes a mistake and sets one relief lower that the others, like the 3pt, that relief will relieve only when you are using the 3 pt.

The 3pt relief setting will not affect the remote valve or the FEL valve.

Why you say, because the FEL cyl develops the pressure and if the pressure exceeds the FEL valve relief setting, the fluid will divert to tank. No fluid goes downstream.

So in essence, you have to think a little to know what is actually happening.

You have to know how each valve works, and what it is supposed to do, and how to interpret the indications when it is not working.

You could get by with one relief on the first valve. You can make the FEL relief operate by setting the pressure for the other valves higher than the FEL setting.

That is all I know and I am sticking with my story.

 

[J_J]

Thanks for the quick reply.

I chose CC valves because my thoughts were that I was simply adding four valves, in parallel, into the interconnection between the P and PB that needed to be maintained when I took the BH off. Seeing as how there should always be flow through that part of the circuit between the P an PB, I didn't think that the CC would be a problem.

As far as where I was inserting the gauge to get the reading, I put the gauge on a tee right after the QC fitting and before the first DCV. If you need a more detailed schematic please let me know.

I am a little curious how they told you to connect those valves.

Did they ask you what they were for?

 

[skyhook]

JJ...:thumbsup:

 

[Tx Jim]

LeeWorm
I agree CC valve on an OC center is a big no-no and vise-verse for OC on a CC center another big no-no.

 

[LeeWorm]

JJ & Jim,

Thanks for the verbal wrist slap and the input. To answer the question JJ, Northern Tool did not ask what I was hooking up. If you have a moment; take a look at these one line schematics which pretty much depict both the layout as well as the train of thought that went into this.

I chose to go with CC valves because I was under the impression that I would not be truly dead heading any the legs of the circuits as I was providing a continuous path for the pressure being routed through the PB.

If I need to swap out to OC valves will I have to re-plumb the subplates in series or can I keep them in parallel as they are plumbed now?

 

[LeeWorm]

Also, to answer the question about how long I have had these valves tied into the hydraulics...just a couple of hours which constituted sporadic testing of the functions and pressures. So if the PRV on the FEL is bypassing then it hasn't been for any real extended period of time or prolonged use.

 

[rayclar]

Very educational JJ thanks.

 

[J_J]

JJ & Jim,

Thanks for the verbal wrist slap and the input. To answer the question JJ, Northern Tool did not ask what I was hooking up. If you have a moment; take a look at these one line schematics which pretty much depict both the layout as well as the train of thought that went into this.
View attachment 394882
I chose to go with CC valves because I was under the impression that I would not be truly dead heading any the legs of the circuits as I was providing a continuous path for the pressure being routed through the PB.

If I need to swap out to OC valves will I have to re-plumb the subplates in series or can I keep them in parallel as they are plumbed now?

In OC hyd circuits, the flow is in series from pump to tank.

So with all OC valves, the pressure line is the input, and the PB passes fluid to the next valve IN port.

With a three gang subplate, the ports are connected internally, so that on the basic subplate, you have one IN port, a tank port, and work ports for each valve. The pass through fluid for the subplate is through the tank port.

You could call the tank port the PB if you want as it has a 3000 psi + rati
The subplate tank port does not go to reservoir unless it is the last valve in the hyd circuit.

Your hyd circuit should look something like this.

Pump to FEL, PB out to subplate IN port, subplate tank port to 3pt IN port.

If you want a relief valve for the subplate, they do make them with a relief port.

The relief for the solenoid valves is upstream, the lowest setting relief valve in the series flow path.

I recommend sending your CC valves back and exchanging for OC and OC subplates.