Why 3 lines for the backhoe attachment?

[MahindraMan1984]

Hi folks. Just reading through to solve my confusion when thinking about adding a 6 spool valve on my '23 2638.
Im confused about which lines to hook up to the new valve body. I will be using a 6 spool 4 stick valve body with 2 sticks controlling 2 spools each and the other sticks only using 1 each such as the hoe valving. Between the hydraulic top and side links and my 3 function grader blade, I will need 5 spools. My confusion begins on which (2) lines of the 3 left behind after removing the hoe, need to be used to power my new open center valve body? Or do i need a valve body with 3 line input? Most setups i have seen, solenoid actuated or manual stick, have only utilized the in and out flow of the rear remotes, because they dont have the additional return line such as mine. These are factory installed lines and need to be looped when the hoe is removed, im assuming to be able to have function to the 3 point. For an example. Lets say I want to run an attachment with the standard 2 lines, doea one go to the loose return line or does that stay disconeected and do i use the 2 stationary lines. Just FYI I also have an additionl 3rd function run to the back fed from the diverter on my loader for the grapple.
I have attached some pics of the lines looped, the lines loose after hoe removed, hoe lines attached and a rear of the tractor with view of 3rd function.

I hope one of you can clear this up for me because my head is spinning. Thanks to all!!

 

[MahindraMan1984]

In addition to my last post here is a picture of the routing of lines into the valve body of the model specific backhoe, Mahindra 60B. It is clear as to where they attach on the back end of the tractor.

 

[MahindraMan1984]

Maybe if the open center system is explained the answer will appear.

In an open center system the pump moves oil, it does not make pressure, in an open center system oil MUST move constantly with the least resistance possible or something is gonna break. I once broke the center section of a pump when the couplers did not connect properly!

Pressure is generated when a load is placed on the system ie the loader is lifting a load. the pressure generated is only enough to overcome the load. More load, more pressure required. A relief valve prevents excessive pressure in the system

Speed of lift is controlled by the volume of oil produced by the pump usually rated by GPM or gallons per minute. GPM of pump or speed of pump.

Power beyond. A hydraulic valve usually has a supply and a return. When oil is to be "sent" to another valve a Power Beyond plug is installed. This serves two functions.. One it takes the load off the seals in the valve. 2 the oil in directed thru the valve with full flow and will not interfere with the function of the valve. Example if a 2nd valve is plumbed into the return port the valve can do weird things when the second valve is activated. Such as the loader may raise or the bucket dump. This is the reason for three hoses.

The power beyond can hook up many valves For example the loader valve to the backhoe valve to the three point valve.

When a valve uses a power beyond fitting it must have a separate return to tank, so 3 hoses or lines. BUT if the 2nd valve is taken out of the system such as taking the backhoe off two of the lines MUST be hooked together. Why? remember open center MUST flow oil. If you hook the supply hose to the tank hose you eliminate the three point hitch and oil just returns to the tank.. If you hook the correct hoses you have your three point hitch back.

Your original question was "Why are three lines needed?" I hope I have explained why. But remember each valve needs its supply, power beyond (except the last valve) and the return to tank to handle the return from the cylinder or motor.

I tried to find a diagram of power beyond but only could find super technical explanations that took a well trained Xpert to understand.

By the way an Xpert = In math you solved for the unknown or X in science class you learned a spert was a drip under pressure. So an Xpert is an unknown drip under pressure.

Have a great day.

So in the situation your explaining, how then would you hook up an implmement that only utilizes on function or 2 hoses? One of the couplers would remain open. Im assuming you would not dead head the system. Ive posted to this thread with pictures of my 2638 rear spool setup on the next page if you wouldnt mind giving it a glance, you will see my predicament. Thanks!!

 

[K5lwq]

Hi folks. Just reading through to solve my confusion when thinking about adding a 6 spool valve on my '23 2638.
Im confused about which lines to hook up to the new valve body. I will be using a 6 spool 4 stick valve body with 2 sticks controlling 2 spools each and the other sticks only using 1 each such as the hoe valving. Between the hydraulic top and side links and my 3 function grader blade, I will need 5 spools. My confusion begins on which (2) lines of the 3 left behind after removing the hoe, need to be used to power my new open center valve body? Or do i need a valve body with 3 line input? Most setups i have seen, solenoid actuated or manual stick, have only utilized the in and out flow of the rear remotes, because they dont have the additional return line such as mine. These are factory installed lines and need to be looped when the hoe is removed, im assuming to be able to have function to the 3 point. For an example. Lets say I want to run an attachment with the standard 2 lines, doea one go to the loose return line or does that stay disconeected and do i use the 2 stationary lines. Just FYI I also have an additionl 3rd function run to the back fed from the diverter on my loader for the grapple.
I have attached some pics of the lines looped, the lines loose after hoe removed, hoe lines attached and a rear of the tractor with view of 3rd function.

I hope one of you can clear this up for me because my head is spinning. Thanks to all!!

Does your new valve have the power beyond sleeve installed? You will need it to power valves down stream from the new valve. The you would install the valve like the PDF you posted says to connect the backhoe.

Once the valve is plumbed with the 3 lines (power in, return to tank and power beyond), then the 2 hoses for a particular implement will plug into the valve on whichever of the 6 spools you want to use for that function.

I may not be understanding your question correctly. If not, let me know where you are confused and I will try to help.

 

[MahindraMan1984]

Does your new valve have the power beyond sleeve installed? You will need it to power valves down stream from the new valve. The you would install the valve like the PDF you posted says to connect the backhoe.

Once the valve is plumbed with the 3 lines (power in, return to tank and power beyond), then the 2 hoses for a particular implement will plug into the valve on whichever of the 6 spools you want to use for that function.

I may not be understanding your question correctly. If not, let me know where you are confused and I will try to help.

Yes It does have a N port that could be used as power beyond, though, I should not need to use the power beyond port on the new valve body as I do not need to produce any more PB flow downstream. I should simply need a power in line (p port) and a return line (T port). I am planning to take power from the existing backhoe lines (with a simple T fitting) at the back of the tractor that are used to function my back hoe, when it is not attached. All while keeping the loop lines in tact.

The confusion for me is which lines for the backhoe connection do what function? One should be power in, one should be return to tank and the other is a loop. I assume the loop is to power the TPH when the BH is disconnected. My assumption is as follows, please correct me if I'm wrong.:
The top (male coupler): Is the return to tank line.
The bottom (female coupler): Is the power line
The detached male line (or looped to bottom fem coupler): Is the power supply to the TPH

My theory is to T off of the upper male coupler to access a return line (T port on new valve) and T off of the bottom female coupler to provide power to the new Valve body (P port). The other option for the return is to t directly into the return line on top of the TPH case, directly behind the toplink, you can see a line going into a block.

I'm hoping that makes some sense.
Thanks for any additional input.

 

[Bentrim]

Power beyond port of the loader valve hooks to the hoe inlet (P)
Power beyond of the hoe hooks to the 3PH control valve.
T on hoe valve hooks to the return to sump.
When removing hoe the line from the loader MUST be hooked to the 3ph if hooked to the sump you will not have 3ph.
If left unhooked it will deadhead and either blow a relief valve continually OR break the weakest link, (pump, hose or a fitting.)

Without a power beyond all oil will return to sump and provide no pressure to the next valve
With Power beyond installed the is flow provided to the next valve buit for the valve to funcion correctly a return has to be installed in the vave.

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