Looking for some help from the hydraulic masters on here. I am ready to add a 3rd function to my B3200. I have the backhoe loop so I know I need to remove the Power Beyond line running back to the back hoe I need to route that line through the new valve and then back to the backhoe connection. My question is does the valve need to be power beyond or would open center be acceptable. Would open center only effect the backhoe and three point hitch flow if I was trying to use the third function and the backhoe or three point at the same time????Please help
Need some advice on 3rd function valve
- Thread starter BossHogg77
- Start date
It needs to be both. Power beyond is a special port that is used to provide power to another device down stream, as opposed to always dumping back to the tank.
Thank you for the response but now I have more questions. I think power beyond would be the best option but it is my understanding that when a open center valve is not being used the fluid just passes through to the next valve which would be my backhoe or three point hitch depending on what's booked up. Is this correct?? My concern is starving the backhoe or three point hitch while the 3rd function is being used. But I don't see when I would be using my grapple and backhoe or three point lift at the same time. Does this make sense???
Why not use a diverter valve on your bucket circuit to operate the grapple? the problem with electric third function valves is that there is no way to feather them so you have no "feel" on your grapple. also the diverter valves are (usually) a little easier to plumb up. some people express the view that the live third allows you to operate the grapple and the loader at the same time, this is not true! If the third function is before the loader valve it will have priority, if it is after the loader valve has priority, you can only operate one function at a time with open center, power beyond hydraulics!
I think I could make either work I was just going off of everyone's recommendations for the elec.over hydraulic. That option raises more questions from me, that type of valve would be after the loader valve, correct?? My tractor has steel lines all the way up to the FEL. I don't think I would want to cut into those lines so would I add the valve up front by the quick connects?? And would the Valve use the curl function and then tee into the return line???
A diverter valve selects either the bucket cylinders or the grapple cylinders when you push the button then you use the bucket function on your loader valve. they have 6 ports, 2 in ports from your bucket hoses and two out to either the bucket or grapple. I usually mount them on the loader boom close to where the hoses from the loader valve attach to the metal pipes in the boom.
Yes, that is how it works, but you have to have a power beyond port if you have another valve down stream. Doesn't matter what valve you use the first in line gets priority so you'll be "starving" something if you're using full flow on a valve. Other than the FEL and 3rd function it's not likely you'll be using two valves at the same time anyway.
Thank you guys for the input and I think I understand how the diverter valve would work but the selector valve I don't quite understand so first of all is there a elec over hyd valve with power beyond?? I haven't seen any that have power beyond but let's just say I could find one. Right now my backhoe has one line in and one power beyond line out to power three point lift. Does the power beyond valve need a tank return line??? Everyone talks about a tank line but my backhoe doesn't have one it's just a loop in the valve and out to lift arms. So if I put a valve in I would have a line (PB)coming into the valve from the tractor that valve would have two lines going to the cylinder and then the PB out of that valve back to the backhoe loop??? Does this would right?? Please excuse my ignorance on hydraulics I just really want to get this right before I start buying parts
You could just buy a cheap spool valve and plumb it into the backhoe hoses and it likely would work fine! There are at least two reasons why it isn't considered good practice though! The first one is what we call intensification, if you direct oil to the base of a doubleacting cylinder, the oil returning from the other end will be a lower flow at a higher pressure if it is continuing to another valve downstream. The powerbeyond prevents this by directing that flow of oil back to the tank but there is no flow at this time to any valve downstream. ( the only time you get power beyongd is if the valve isn't doing any work) the other reason we don't continue the return oil to the next valve is because it pressures up the ends of the spool valve if work( backpressure) is being done from the downstream valve!
Now Kubota know that you can't use your three point hitch with the backhoe on so they didn't feel it necessary to put a power beyond line on your backhoe. On a Tractor like the BX24 they DID use the third line because the backhoe is the first valve in series and you certainly could overpressure the rest of the system if were to extend the boom and operate the loader at the same time were a power beyond system not incorporated.
Did I help any or just muddy the water even more!
Still trying to digest everything u said but I think I understand right now my backhoe is the first valve on the power beyond loop so if I operated the lift arms and backhoe at the same time I could create the back pressure issue? But in this case I'm using the PB line which is seperate from the loader outputs ( same valve but totally different line out of the valve) right so far?? So because I'm putting a valve before the backhoe valve I need to run the power beyond from the valve on the tractor (loader valve)to the new valve and then a PB line back to the backhoe loop but also the outline from the new valve could be tee'd Into the rubber tank return line (low pressure I assume)??? Hopefully this is right and I won't have anymore questions.
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The new valve should have a "P" port, A "PB" port and a "T" port the "PB" line from the loader valve goes to the "P" port, the Line to your backhoe goes to the "PB" port on the new valve and the "T" port on the new valve goes back into the transmission case however you want to do it! The new valve also has two cylinder ports that go to the grapple cylinders. Be sure the new valve is rated for at least as much flow as the tractor maximum. (bigger is better within reason!)
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Your new valve doesn't need a relief valve in it because it is downstream from the loader valve which does have a relief valve and is power beyond.
Thank you guys so much for educating me on this now I understand either valve and can start shopping for the best setup.