Power Beyond or HPCO valve help needed

[bbutcher]

I have a Satoh S650G, a.k.a. "Bison" with a front end loader (FEL). The tractor has a hydraulic system that raises the 3 point hitch. There is a triangular shaped plate under the seat that has two hydraulic lines connecting to the FEL (a pressure line and a return line) control valve. Today I connected my backhoe attachment by adding tees in the lines, so the backhoe control valve is in parallel with the FEL control valve. As connected neither the FEL nor the backhoe operate correctly. It appears that when the control valve for either the FEL or hoe is centered the hydraulic fluid is bypassed from the high pressure line to the return line, thus it never develops pressure enough to operate the cylinders. I assume this is called an open control valve?

If I open any one valve for the FEL, and simultaneously open any one valve for the hoe, both move correctly. As a temporary measure I tied the FEL raise/lower valve in the lower position, and once the FEL is all the way down, the hoe valves work correctly. Likewise I can tie any hoe valve open and once the associated cylinder reaches the end of travel, the FEL works correctly.

I have heard of a "power beyond" valve (also called "high pressure carry over") that I think will force both systems to work correctly together. I assume that somewhere inside the tractor hydraulic system is something similar since both the 3 point hitch and the FEL work together correctly. In fact the triangular plate mentioned above has 4 o-ring sealed ports, but two of them are just blocked off (never drilled) while the other 2 go to the FEL hoses (pressure and return). Does anyone know if I drilled holes and added 2 more hose connections to the blanked off ports to operate the hoe if this would solve the problem? I found Brendan Casey's description of the power beyond valve, but I don't understand just how to connect it if I found one. Do I need to modify my control valves to make them closed? From what I have read it is necessary to size the power beyond valve for the pump capacity, which is 4.1 GPM for my tractor.

Am I on the right track here, or is there something else I should do? http://www.tractorbynet.com/forums/images/smilies/confused.gif
Bob

 

[J_J]

Yes. you should size the valve for the GPM's. You can not connect the valves in parallel

I believe the pressure line from that plate, should go to the input of the BH valve, and the BH out should go back to the return on the plate. Can you show pictures of the plate, and was anything connected before?

All open center valves should be in series.

 

[kennyd]

Welcome to TBN


Hydraulic fluid, like electricity will "take the path of least resistance". So when you added the valve with the Tee's, and operated the FEL valve since there was resistance added the fluid just went through the newly added hoe valve, and vise/verse. Make sense?

All new valves MUST be added in series, this is where the PB (power beyond) comes into play. Every tractor is different, so adding pictures of your's will help us help you. Now many hoses are connected to your FEL valve, 6 or 7? IS there a port marked PB, BY, or BYD on it?

Also, do some searching 'round here...there are LOTS of threads describing how to add a valve or "remote".

 

[J_J]

KennyD, I sure wish you would unblock me, as you are repeating a lot of my post. I believe it is a good thing that people want to help others with problems, however, these people that have people blocked out , is not a good thing, and are just repeating the data already given. It's like they think we don't exist. I don't have you blocked out, and read all your post.

Since he has me blocked out, he probably can't read this.

 

[jake98]

Since he has me blocked out, he probably can't read this.

Some of us thick skulls need to hear things twice anyway..

 

[bbutcher]

Thank you KennyD and JJ for your replies. I did find a website saying I should connect open center valves in series, so I did that. Now it works more or less correctly, exept the FEL tends to raise slowly when I use the BH. I am also experiencing leakage somewhere in the spool valve for the FEL. I think the problem is related to having the output of the FEL spool valve at high pressure instead of going back to the tank, but I may just need to replace some seals. I need to identify the power beyond port if one exists on the FEL spool valve. I did find some info on the Prince website that may be helpful in getting it connected correctly. I will try to get some photos and maybe some more details on the spool valve if it doesn't snow today.

 

[J_J]

If the FEL valve is the first valve inline, and you operate the levers full up or down, you could use all the hyd flow from the pump, and the 3pt would get none. If using only some of the lever travel, some of the hyd fluid would flow through the open center valve, through the tank port, and back to the 3pt, and both would work, only slower.

If you only use the 3pt, then the complete hyd circuit from pump to the 3pt is high pressure, depending on the load.

The only time the out/tank port has high pressure is when you are using the 3pt, which means that the FEL valve, hose and 3pt valve are seeing the high pressure.

This is why, when someone is replacing a FEL valve, to select a valve that will handle the high pressure on the out port of the FEL. Tank ports are usually low pressure.

The BH valve should be in series and before the 3pt. This will cause all the valves in the circuit to see high pressure if the 3pt is used. If you disconnect the BH, then you need to jumper the connections for the BH, to provide a complete path for fluid flow through the 3pt.

 

[bbutcher]

Thank you for the info JJ. I have more information now. The 3 point system is plumbed in as part of the tractor and it is not easy to access the hydraulic line between it and the pump. The fluid from the 3 point goes to the "block" I mentioned previously, shown in the photo below. The two lines from this block originally went to the FEL control valve, a Gresen 2702 which seems to not have a power beyond port (photos below) unless the plugged port shown is it.

I have re-plumbed the system to use the oil coming from the 2702 return as the inlet for the BH. All systems function correctly, including the 3 point, other than the oil leak in the 2702 and the slow movement of the FEL while using the BH. When I remove the BH, I will install a short hose between the two quick connect fittings to route the oil to the FEL.

It appears that maybe I should route the oil to the BH first to avoid high pressure on the outlet port of the 2702. The BH control valves may have a power beyond port, but I do not have good photos of them, and I will need to remove some panels to even get a manufacturer or model number for them. The BH is a Kelly B-750 and the diagram shows connecting to a power beyond port for the FEL (shown below).

 

[MtnViewRanch]

Just want to give a friendly warning, in your pictures it looks as though you are using standard water pipe fittings. If they are water pipe fittings, they are not rated for the hydraulic pressure that you are running through them. I know that this has been done for many years and sometimes all is fine, just wanted you to be aware of the possible problems that may occur.

 

[kennyd]

Just want to give a friendly warning, in your pictures it looks as though you are using standard water pipe fittings. If they are water pipe fittings, they are not rated for the hydraulic pressure that you are running through them. I know that this has been done for many years and sometimes all is fine, just wanted you to be aware of the possible problems that may occur.

Good catch MVR:thumbsup:

Regular iron pipe fittings are usually rated for only 150 or 300 PSI-especially the ones now that are cast on China. These fittings can see 3000+ PSI with shock loads on a loader or backhoe.

 

[bbutcher]

Thanks for the tip. Yes, I think some of them are just water pipe fittings. I need to upgrade them although some have been in service for years now. They are not very expensive to buy the correct ones.
Bob

 

[bbutcher]

I think I finally found an explanation that I could understand. This will probably be obvious to those familiar with hydraulics, but it really helped me understand what "power beyond" is all about.

First I checked my backhoe and found it has a Gresen series V12 valve. I contacted Parker Hydraulics and spoke with Mr. David Fabian, who was extremely helpful. First he identified the 2702 casting as an SP2 series valve, and explained some were made with power beyond capability and some did not have this option. If it has power beyond there will be another port located near the return to tank port, which my valve does not have.

On the other hand, the V12 series does have power beyond capability, and just needs to be configured correctly. All that needs to be done is replace the open center plug with a "power beyond sleeve" in the conversion port located on the output end of the V12 series backhoe valve, and connect as shown in the attached diagram. Mr. Fabian then explained that the series connection I used would result in high pressure being applied to the tank port on the 2702 valve whenever the backhoe valves are actuated. This high pressure on the tank port is applied to the seals on the ends of the spools, causing them to leak and will eventually blow the seal.

Mr Fabian explained the concept of configuring valves, and I sketched some simple 3d drawings showing the oil flow in each configuration. The sketches are only the output end of a generic valve but show how the V12 series is changed from one configuration to another. The three configurations I sketched are open center, closed center, and power beyond.

In all configurations the oil flow will be to the tank port when any valve is actuated, forcing oil to a cylinder. Likewise if the pressure relief valve opens (due to overpressure) the oil will flow to the tank port through another path not shown on my sketches. Therefore both the backhoe and FEL valves must have a return line connected back to the tank.

The difference in configurations only affects the oil that flows (or tries to flow) through the center of the spools when no cylinder is actuated.The standard configuration is open center, which means the oil flowing through the spools in the center (non-actuated) position is always returned to the tank port.

A closed center configuration blocks the oil flow in the center, causing the pressure at the inlet to rise to the level that the pressure relief valve opens (usually 1500-3000 PSI). This forces the pump to work hard all the time and wastes horsepower, but it allows a parallel connection of valves provided they are all closed center, with maximum pressure always available to all valves.

In the power beyond configuration, the center oil flow is diverted to a third port which is then connected in series with the next valve in the system. Note that if several valves are series connected, all valves except the last one in the series string must have power beyond configured. The last valve is open center, so when all valves are in the center position, oil will flow back to the tank with no high pressure produced anywhere in the system.

If any valve in the series string is actuated, the oil will be diverted through a cylinder at high enough pressure to move the cylinder, or if the cylinder cannot move (end of travel or too much load) then the oil will flow through the relief valve to the tank. Only one valve at a time may be actuated since the oil will be diverted through a cylinder and flow back to the tank rather than flowing through the power beyond line to the next valve (i.e. If backhoe is in use, no oil is sent to the FEL in my case).

I hope this will help another novice to understand the how and why of power beyond.

 

[J_J]

Good illustrations and write up, thanks.

 

[JD5210]

First bbutcher thank you for your post #12. Someone, please explain what I am missing. To me it would appear difference between the diagram in post #8 and the one in post #12 is that the BH and FEL position is reversed. The point made in post #12 溺r. Fabian then explained that the series connection I used would result in high pressure being applied to the tank port on the 2702 valve whenever the backhoe valves are actuated. This high pressure on the tank port is applied to the seals on the ends of the spools, causing them to leak and will eventually blow the seal.

Does issue then move to the FEL? If no is it because the BH and the FEL use different valves or some other reason?

I understand you do not want to use pipe fittings. What are peoples fillings on using the Teflon tape?

Thanks.

 

[J_J]

Some valves might can take the full pressure on the tank/out port, but most can not. You may see this on the FEL valve going to the 3pt circuit, but the 3pt probably doesn't develop the full pressure of the pump. Therefore the purpose of the PB is to allow full pressure through the open center circuit. It really doesn't make any difference which valve is first in line, except if the first valve is activated, it may take all the flow in the circuit if the levers are fully activated. If any two valves use only half lever, then each valve will get some flow. If the last valve in-line is activated, the complete circuit is pressurized from pump through all valves ,and to the valve in operation. Most times when using the BH, the FEL valve is not utilized, , and vice-verse.

 

[JD5210]

J.J. thank you answering my question!

 

[kennyd]

What are peoples fillings on using the Teflon tape?

Thanks.

Tape should NOT be used in hydraulic systems. A PTFE past is recomended. This question usually will result in much debate...

 

[MtnViewRanch]

Kenny, a question for you. Have you ever seen tape used on any OEM applications? Not saying that it's right or wrong, just a simple question.

 

[kennyd]

Kenny, a question for you. Have you ever seen tape used on any OEM applications? Not saying that it's right or wrong, just a simple question.

Admittedly, yes-I have...mostly on things like the cheap logsplitters at TSC, Home Cheapot and lowes and rented equipment. Not on my JD though, but it mosly uses JIC or ORB fittings which don't need any sealant anyway.

 

[J_J]

Teflon tape is used quite a bit. It only takes common sense to not put it on the first and second thread, and when removing the fitting, to clean out all the old Teflon debris.