how to tie into PB

   / how to tie into PB
  • Thread Starter
#11  
Yes, I can read it, and it says that the valve comes as open center, and if you want PB, to purchase and install the PB sleeve.

What the PB sleeve does is to separate the main gallery and OUT port and lets the hyd flow pass downstream through the PB fitting for additional valves or just to 3pt.

The cyl's expended fluid only goes to the OUT port, and most times the out ports go to tank.


Thanks for pointing that out. I know 0 about hydrauics. So, that means I purchase a sleeve for the PB port Then a hyd hose then connect to a valve for a grapple ?? & my loader valve will still have open center ? correct ?

On my yanmar the out port does go to the tank eventually after it powers the power shift & the 3 pt
 
   / how to tie into PB #12  
The picture digagram is just showing the 3 different variations available, open center w/PB, Open center w/o PB, & closed center. You want it to look like th top picture. As JJ mentioned before, do not use the quick couplers go to or out of the valve. Mount the valve so it stays with the tractor if loader is taken off then use quick couplers on the 4 hoses going to the cylinder circuits.
 
   / how to tie into PB
  • Thread Starter
#13  
thank you guys. The pics of the tractor isn't mine. It's 1 I found on the net to show how these are connected. My tractor lines are hard piped (no quick connects) I will call the dealer & see if I can purchase the P B sleeve
 
   / how to tie into PB #14  
On my yanmar the out port does go to the tank eventually after it powers the power shift & the 3 pt

The way you describe the out port it is routed where power beyond should be i.e. it wasn't installed correctly. Out ports are not designed to be pressurized like the power beyond port. Also, separating the out and power beyond ports allows the relief function to work correctly. Hopefully you have a convenient port on your hyd. tank for the return (out) ports to be connected.
 
   / how to tie into PB
  • Thread Starter
#15  
The way you describe the out port it is routed where power beyond should be i.e. it wasn't installed correctly. Out ports are not designed to be pressurized like the power beyond port. Also, separating the out and power beyond ports allows the relief function to work correctly. Hopefully you have a convenient port on your hyd. tank for the return (out) ports to be connected.



On my tractor & other yanmars that I have seen. The H.P. line from the pump is cut. From the pump H.P. the line goes to the inlet of the loader valve. The out port of the loader valve continues on ( I assume still H.P. as there is not a regulator to cut the pressure after it exits the loader valve) to the 3 point part of the tractor. I guess at some point it returns to the sump or transmission
 
   / how to tie into PB #16  
The only difference between the way it is and the way it should be is that the loader valve should be set up for PB with the PB line feeding the 3ph and one more line going from the out port on the loader directly to the sump. If your transmission fluid is separate from the hyd. fluid the casting the lift arms come out of is typically the hydraulic sump.

The way the whole system works is that the hydraulic pump provides positive flow through all of the valves whenever the engine is running. This is sometimes called the power beyond loop. When a valve is actuated, it diverts flow to the working cylinder and for double acting cylinders the fluid on the other side flows back through the valve to the "out" port. Resistance to the cylinder moving causes high pressure in the loop from the pump to the working valve. When the resistance is too high or the cylinder reaches the end of it's stroke, the fluid has no place to go so a relief valve built into the control valve allows flow to pass to the "out" port at the relief pressure which is typically 2000-2500 psi. The simple relief valves used are affected by downstream pressure so if the out port is used as power beyond, valves in series that are operated simultaneously can theoretically cause pressures as high as the sum of their relief pressures. For example in your current setup if you operate the 3ph at the same time as the loader you can create this situation. I know it would be unusual to do that but it only has to happen once to damage the pump. According to experts I have talked to, it is also bad to even have the "out" port exposed to high pressure. That's why it is proper to use valves set up to separate the high pressure power beyond loop from the low pressure "out" ports which should return to the sump, possibly going through a filter along the way.
 
   / how to tie into PB
  • Thread Starter
#17  
I wish I knew how to fix it but, I don't . Like I said in my previous post all the yanmars I,ve seen are plumbed this way in this pic


loader%20shoes.jpg
( This isn't a pic of my tractor. it's another yanmar set up for loader) The small line on top is comming out of the pump. The rubber hose connects to the IN port on the loader valve. The small line on the bottom where the other end of the rubber hose connects . Is connected to the OUT port of the loader valve. My system is connected just like this http://www.hoyetractor.com/support/knowledgebase.php?article=58 system. If you were to take the aux. valve out of the pic . H.P. travels from pump through loader valve then out to 3 point
 
   / how to tie into PB #18  
If your loader valve does not have a PB outlet, and you have been using the tractor for a while, You can use it as is, even though there could be high pressure built up in the valves at times. Any time you use the 3pt and hold the lever until the relief comes on, high pressure is reflected back through all the other valves.

If the out port has seen high pressure many times before, the valve can probably handle it. Also, just about all manufacturers say to route the OUT port to tank, and they also state the back pressure.

I believe enough data has been given here to make some logical decision about what to do.

If you use a valve with only an out port for the fluid exit, you take a risk, and it is your tractor, so do what you want.
 
   / how to tie into PB #19  
You are correct that many grey market tractors are pumbed this way when loaders are added. If the PB sleeve is available, I'd get it and plumb your next valve that way. If not, I'd use the out line to plumb your next function in line. Obviously, using the out is not the best way, but you have what you have.
 
   / how to tie into PB
  • Thread Starter
#20  
Thanks for all the info. provided. :thumbsup:
 
 
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