B3200 rear remotes, is power beyond a must?

[Verticaltrx]

I'm back to thinking about adding a couple SCVs to my B3200. I would like to use a standard, compact, 2 spool valve, open center. I would just install it 'in-line' in the pressure line that goes from the loader valve to the 3pt hitch. i.e. loader valve power beyond port > in port on valve, out port on valve > in port on three point hitch.

I know the way it 'should' be done is to use a power beyond capable valve and run it to the 3pt hitch (and have a low pressure return line), but would I damage anything by doing it my way? I can't see any disadvantage except that I wouldn't be able to lift the 3pt and operate the valve at the same time, which I would never do anyways.

Thoughts?

 

[J_J]

Sounds like you have a good plan. Should work.

 

[kennyd]

I have a valve hooked up on my JD that way, as well as many other JD owners-ONLY because there is no available return port to the tank. Your Kubota will have a return port, so there is good no reason not to use a proper PB equipped valve. Why would you want to anyway?

Now, some will say that if you hook up a valve in series without PB it will blow up due to pressure on the OUT port, but the fact is-many are hooked up his way including 3PH logsplitters and OEM and aftermarket backhoe's and there are not reports here on TBN about cracked or exploding valves.

 

[AKKAMAAN]

Most valves a specified with a max tank port pressure, like this prince RD5000, max 500psi. Why do they have a reason to do that??
#1 valve house is structural weak around tank port and return cores, compared to the high pressure cores...
#2 the o-ring seals that prevent oil from leaking externally around the spool is NOT a high pressure seal

Even if there are no reports on cracked housings, we see now and then reports of leaking seals.....

2c

 

[Jay4200]

Hate to answer a question with a question (or a bunch of them), but I got confused on this thanks to shop guys referencing a 3-hose connection for a loader valve. I still don't follow that, unless one connection isn't used when PB is hooked up on the control valve, which then makes perfect sense.

From what I have read, adding a PB connection (or inserting a PB plug/sleeve into a valve) simply ports the flow output from one hole to another (OUT to PB), forcing the return path to go through the next valve in line. If there is a return hose connected, I guess it doesn't do anything once the PB conversion is made to a valve. Stacks of control valves are simply two-port devices. It seems that a two-hose connection using the out port is exactly identical to using the PB port.

The schematic/block diagram in figure 2. of: Hydraulic valve power beyond or high pressure carry over shows that the PB plug simply blocks the return port.

Lastly, since the last thing in line is the 3pt hitch, doesn't any return line basically become a PB line for the 3pt?

JayC

 

[J_J]

Once you are using the PB sleeve, all fluid from the cyl have to pass through the return or T port. The return or P port is not designed to handle high pressure. The PB outlet with sleeve, carries all the fluid not used by the cyl and send it to the next valve. You can tee into return lines.

 

[Jay4200]

Once you are using the PB sleeve, all fluid from the cyl have to pass through the return or T port. The return or P port is not designed to handle high pressure. The PB outlet with sleeve, carries all the fluid not used by the cyl and send it to the next valve. You can tee into return lines.

Does every remote valve (or valve stack) have to be 3-terminal? My understanding is that the 3pt is last in line, so the last valve would have to return to the 3pt through it's PB (which might just answer the OP question). My backhoe is 2-terminal (explained that it used "special" valves). Would a "special" backhoe valve simply be set up for a high pressure return line?

Edit:
Just found this description:
POWER BEYOND (HIGH PRESSURE CARRYOVER): A sleeve attachment which permits the oil flow from one valve (when in neutral) to be used by another valve downstream. Hence, a 3-spool valve cou1d be connected to a 2-spool valve to create a 5-spool valve, The first valve takes priority and must have a separate outlet port to return oil from an activator back to the reservoir.

So, if the 3pt is last, then remotes do have to be 3 terminal, if it is first (which seems like it makes more sense) then they don't. I guess. Man, I wish I could find a decent schematic somewhere...

JayC

 

[glastron23]

Most valves a specified with a max tank port pressure, like this prince RD5000, max 500psi. Why do they have a reason to do that??
#1 valve house is structural weak around tank port and return cores, compared to the high pressure cores...
#2 the o-ring seals that prevent oil from leaking externally around the spool is NOT a high pressure seal

Even if there are no reports on cracked housings, we see now and then reports of leaking seals.....

2c

I'm having a hard time believing that i have a chance to correct AKKAMAAN.....LOL... i think that you will find that the reason for limiting the tank pressures on the prince valves is due to the internal PR's and the auto cycle circuits that these valves can come with.
So to protect them from a potential problem of having the PR in the valve bank being the only PR in the system and having more than 500psi on the tank line (2000 psi PR setting + 500 psi tank pressure = 2500 psi pump pressure) or (2000 psi PR setting + 1500 psi tank pressure = 3500 psi pump pressure) can we see the problem???? , so they decided to limit the tank pressure.The auto cyclers do not like high return pressure PERIOD ... it really sends them for a loop. I hope this helps???

 

[wdchyd]

Most valves a specified with a max tank port pressure, like this prince RD5000, max 500psi. Why do they have a reason to do that??
#1 valve house is structural weak around tank port and return cores, compared to the high pressure cores...
#2 the o-ring seals that prevent oil from leaking externally around the spool is NOT a high pressure seal

Even if there are no reports on cracked housings, we see now and then reports of leaking seals.....

2c

How about #3 "Series Resistance Adds Pressure".......

If three hyd valves connected inline (no PB)......are actuated at the same time and all three PRV's were set at 2000 psi....What would the pressure at the pump read??

Isn't this the real reason for all this Power Beyond Stuff????

 

[Verticaltrx]

Lots I haven't thought about I guess. I have a setup like the one I mentioned on my NAA, and it has been working fine for several hundred hours. The hydraulics on it are pretty rudimentary however, and if it all goes to **** in a hand basket there isn't anything that can't be fixed. On my Kubota I want to do it right however.


As to the relief valve, if I plumb the SCV 'in-line' what will the effect of the relief valve of the tractor have on it? What will the effect of the relief valve on the SCV have on the rest of the system? What about if it were hooked up as power beyond?

Thanks for the replies.