Hello all, First timer here, I just purchased a Great Bend 651 hoe 3pt attachment and would like to do away with the self contained hyd pump. It wobbles on the PTO shaft and I worry about it wearing away at my RH lower link. I can tell from my 1710 manual that there is an aux port on the RH side of the 3PH adjustment knob that becomes pressurized when the control handle is in the full up notch. Other than having to unpin the 3PH to allow the arms to raise completely, what would be wrong with using this pressure port to power the backhoe? Also, is that the return port just below and behind the aux pressure port? Can not find any specs on the GB651, but similar hoes show 4-5 GPM on the self contained pump at 2250 PSI. My 1710 lists 7.8 GPM at about the same pressure.
Backhoe Auxiliary Port
- Thread starter mfuller
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JC-jetro
Elite Member
Any pics of the port? My question is what happens to the flow in the port once the 3 point goes to the highest point. Would all flow be diverted back diffy? what happens when lift spool goes to neutral? if it is a true hyd port then it should be independent from 3 point lift circuit.
JC,
JC,
According to the manual, this aux port is for rear accessories such as rams or hyd motors on implements. It also says not to place the 3ph control handle in the full up notch if the port is plugged because it will dead head the pump. When you lift the control handle slowly, the 3ph raises slowly to mirror the control handle, then when it reaches the top notch the engine begins to bog down, at which point I quickly dropped the control back down. I will post pics after work.
JC-jetro
Elite Member
I'm just curious if you continue to have flow at any given height of your 3 point system. The spool is open center so when you reach desired height a feed back arm return the all the pump flow to diffy. The location of this hyd block need to be upstream of the spool and not downstream from it.
JC,
You can drop the arms to the ground, then quickly move control to upper-most notch, the arms will raise until they top out, THEN the pump will begin to bog the engine. So, no, I don't believe there is any flow at lower heights of the arms.
I'm not concerned about the 3ph, though. You can't use it while the backhoe is attached anyway. The PB port on the loader valve is plumbed back to the 3 point. Isn't this aux port kinda like a PB port, only you have to leave the arms up to use it?
JC-jetro
Elite Member
I'm knowledgeable with the system in general and what I have. The point I was making if the port is somehow on downstream of the spool then flow is stopped when 3 point reaches any height. The spool on your tractor is the same as mine. This thing does not have a spring loaded detent mechanism to stop and divert flow to the hyd reservoir. Thru a feed back arm and linkages internally return of spool valve to neutral is achieved. in other word at any given height of 3 point the flow is all diverted. If that was not the case you would continue pumping oil in to lift cylinder causing the lift to go to max height till you dead head the pump. There are a lot of guys here that could also chime in to help.
I really think if you have a PB port it has to be plumbed to auxiliary hyd block before lift spool. It does have to be independent from the lift. Look at the pic below, someone rigged up the absolute cheapest remote there is to the 3 point. Where the connection is made where you hook up a gauge to measure hyd pressure before flow goes to lift piston. It took only a quick connect and 18" of 3/8" hose. the problem with that is flow there will be stopped as soon as 3 point reaches any give height. I have not experimented with it yet. it would be great if flow would continue. May be that can be achieved by removing the feed back arm.
Guys, any one has any opinion about what I said?
RickB, am I thinking it correctly?
JC,
OK, this is exactly the same setup I am going to try, only I can't tell where he plumbed in his return. I think the square head plug right in the center of the picture is where you would return the fluid back to the case. And I don't understand why you say the flow stops. This is not a test port, the manual describes it as an "auxiliary port for rear cylinders and motors". Has anyone else had any experience with this?
JC-jetro
Elite Member
Yes , you can use that square plug as return path to the diffy. I have taken that off and it does open to the diffy. Where the aux hose is connected is downstream of the spool. When spool goes to neutral all flow should by-pass thru the spool back to diffy bypassing that point. I hope I'm wrong as that would be an excellent connection point to plumb up a very simple PB port. It might work with one way cylinder. I'll be interested to see how it'll work as I said I have not personally tested that port. Why don't ya post a picture of what you have. On my manual that plug is clearly shown as a pressure test port.
JC,
