General Hydraulic Knowledge Question

[Jay4200]

I have two "power beyond" ports on my L4200 (open center system) that run my backhoe. There is a by-pass plumbed in for when I am not using the power beyond hydraulics - I have to disconnect a hose and re-connect another hose to perform the by-pass function. I need 2 remotes to run my snowblower chute hydraulics. I planned to use the power beyond ports and simply connect a couple of valves and make the two remotes I need.

I stopped by the tractor shop today, and discussed my plan, but they told me that 'power beyond' is not a supply and return line, but is pressurized on both sides, and that normal OC valves will cause a dead-head condition and won't work. They say that the backhoe valves are special and can run without a sump return line by some kind of magic, and are super expensive as a result. Evidently, I need a third line that returns to sump. Also, I evidently have no understanding of how open-center hydraulics work, I guess.

After the conversation, I am confused on a whole new level and have no clue how to proceed. All I want to do is generate a couple of remote hydraulic connections for my chute controls - I have the 'power beyond' ports at my disposal and expected that I could use them, but I guess I don't understand what they actually are. If anyone can explain what is going on in layman's terms, or lead me to a link that will explain this type of system, I would be forever grateful.

Thanks - JayC

 

[kennyd]

Your tractor shop is clueless-he does not know what he is talking about.

One hose is the "supply" or "feed", and the other is the return. All you need is a regular OC valve.

 

[AKKAMAAN]

I have two "power beyond" ports on my L4200 (open center system) that run my backhoe. There is a by-pass plumbed in for when I am not using the power beyond hydraulics - I have to disconnect a hose and re-connect another hose to perform the by-pass function. I need 2 remotes to run my snowblower chute hydraulics. I planned to use the power beyond ports and simply connect a couple of valves and make the two remotes I need. that should work!

I stopped by the tractor shop today, and discussed my plan, but they told me that 'power beyond' is not a supply and return line, but is pressurized on both sides, and that normal OC valves will cause a dead-head condition and won't work. They say that the backhoe valves are special and can run without a sump return line by some kind of magic, and are super expensive as a result. Evidently, I need a third line that returns to sump. Also, I evidently have no understanding of how open-center hydraulics work, I guess.

After the conversation, I am confused on a whole new level and have no clue how to proceed. All I want to do is generate a couple of remote hydraulic connections for my chute controls - I have the 'power beyond' ports at my disposal and expected that I could use them, but I guess I don't understand what they actually are. If anyone can explain what is going on in layman's terms, or lead me to a link that will explain this type of system, I would be forever grateful.

Thanks - JayC

I guess you will be disconnecting the backhoe, when you run your snowblower attachment.......
You should be able to connect the snow blower valve the same way you connect the backhoe valve. Backhoe is open center too


I am sure kennyd will fill in too....woops he obviously did.....hahhahah

 

[Jay4200]

Your tractor shop is clueless-he does not know what he is talking about.

One hose is the "supply" or "feed", and the other is the return. All you need is a regular OC valve.

Thanks.

The description/comparison they gave me was (compared to a water well system) that the supply side was like a hose faucet, and the other was like a return to the pressure tank. A sump return would be analogous to a line dumping back into the well (I guess). So, while fluid can circulate through the circuit, both sides are pressurized. I have no idea what the **** that means.

So, according to you, my two power beyond connections are what I thought: a high-pressure line coming from the pump, which would be in series with, and probably at the end of the other valved connections, and the other is a straight return to the sump?

During this explanation, they also told me to look at my loader valve for comparison - evidently that is a 3 hose setup (in, return, sump)? I haven't been back to my tractor since, so I don't know. I also have the power beyond and bypass lines connected up there, so it is quite a bundle. I suppose I can use one of the connections up front to make the remotes too...

Thanks - JayC

 

[Jay4200]

I guess you will be disconnecting the backhoe, when you run your snowblower attachment.......
You should be able to connect the snow blower valve the same way you connect the backhoe valve. Backhoe is open center too

Yes, I will (and have) disconnected the backhoe. It is currently off and I am running a 3pt blade. The power beyond backhoe connection is bypassed by moving a line from one connection to another that is up front by my bucket.

thanks - JayC

 

[kennyd]

Thanks.

The description/comparison they gave me was (compared to a water well system) that the supply side was like a hose faucet, and the other was like a return to the pressure tank. A sump return would be analogous to a line dumping back into the well (I guess). So, while fluid can circulate through the circuit, both sides are pressurized. I have no idea what the **** that means.

It means they have no clue

So, according to you, my two power beyond connections are what I thought: a high-pressure line coming from the pump, which would be in series with, and probably at the end of the other valved connections, and the other is a straight return to the sump?

The return line may go to the 3PH, or directly to the sump-doesn't matter either way. You can search hundreds (if not thousands) of posts here on TBN about adding a valve to the PB line. They all will agree with me and NOT your dealer (or private shop).

During this explanation, they also told me to look at my loader valve for comparison - evidently that is a 3 hose setup (in, return, sump)? I haven't been back to my tractor since, so I don't know. I also have the power beyond and bypass lines connected up there, so it is quite a bundle. I suppose I can use one of the connections up front to make the remotes too...

On your loader valve you have 3 main connections (and 4 that go to the cylinders), they are IN, OUT (or "T" for Tank) and PB (or BYD) for the power beyond. The PB port feeds the next vavle in the series, which in your case is the backhoe (if connected) and/or the 3PH.

 

[MicroPilot]

Generally on OC circuit tractors, is the TPH the last work device in the circuit? In other words, will all other cylinders, motors, etc, be plumbed in between the pump/PRV and the TPH?

Are there PRV valves on individual work system, or only the "master" just after the pump?

 

[J_J]

Yes the 3PT/TPH is usually the last component in the hyd circuit, and the main PRV will protect the complete circuit, if the components are selected for the tractor psi.

Most valves have a relief.

PRV's are designed to protect a circuit/component. If you are using a component that has a lower psi rating that the pump, then you would want the relief for that valve to protect that circuit. For instance, a BH, that was designed for 2500 psi. The tractor may have a 3000 psi PRV.