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Discussion Starter #1
Hey there, new to GTT, but I've been reading it for years and decided, since I've got an issue with my tractor, was hoping someone here could help me out. I recently added a single SCV to my 2720 by using the dealer installed power beyond (for a new backhoe). I used an open center SCV and connected the PB to it. I planned to use it on a rear blade with hydraulic angle. When I finished the install, everything worked great in the garage. When I got a chance to use it for an actual snowfall, again, it worked flawlessly. I used it for about an hour that morning. That evening, I got the tractor out of the garage and went to move more snow and after I lowered the blade with the 3PT, it would not raise back up. Nothing. Tried everything I could think of, hydraulic fluid level is fine, lowering drop speed was good. Still nothing. Finally, had to unhook the blade where it was at and got the tractor back in the garage. Looking it over in the garage, I can lift the 3PT arms up with my hands very easily, but the lever does nothing. Any thoughts?? Any help would be greatly appreciated.
 

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Have you checked and reconnected all the hydro couplers? Does it sound like the hydro pump is in bypass when you try to raise the 3pt? Or in bypass while running?
 

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Discussion Starter #4
Yea, I have all the couplers connected. I even took my SCV setup out of the loop and looped the hose back as it was before when I don't have the backhoe attached and it still doesn't work. I will take pictures in the daylight. Could my new SCV setup somehow have screwed up hydraulic system?
 

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Did you use a Power Beyond equipped valve and a separate return line? In other words do you have three lines (not counting the work ports connected to the cylinder) connected or just two?


I can lift the 3PT arms up with my hands very easily,
FYI that is normal, there is no down pressure except gravity so the arms can float up.
 

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Discussion Starter #6
KennyD, no I did not use a power beyond equipped valve with a separate return line, just a single SCV open center valve from Northern Tool. I figured I could use the existing power beyond lines to power the SCV. See my setup below. To power the SCV , I disconnected the looping hose and took the male end to one side of my valve and brought the other hose from the valve and put it back into the female.Currently, I have the power beyond unhooked from the SCV and back in it's normal loop and still no 3PT working. Loader, power steering, transmission all working fine.

20180211_122432 (2).jpg
20180211_122417 (2).jpg
 

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Is the tractor making any unusual and strange noises? Can you make the hydraulic system go into relief? You should be able to hear the relief valve lift when you max something out like the loader.
 

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I fear that some backpressure may have been created back towards the rockshaft/3PH valve and damaged it, this is the concern when not using PB equipped valves.

When everything was working, and the new valve plumbed in, did the blade see any unusually high forces while operating?
 

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I fear that some backpressure may have been created back towards the rockshaft/3PH valve and damaged it, this is the concern when not using PB equipped valves.

When everything was working, and the new valve plumbed in, did the blade see any unusually high forces while operating?
I'm thinking the same thing Kenny. I would also want to check the rock shaft draft feedback control linkage to make sure it's neither disconnected nor jammed.

If the SCV plumbing was causing a restriction the hydraulic fluid may have become overheated and caused a lift piston or spool valve to score or seize. An piston seal or o-ring may have been damaged.
 

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Is that the Nortrac 45462? If so, you would have needed to also purchase the optional power beyond plug. Otherwise from what I see you were trying to run the rockshaft on the tank return of the valve.

Can you make the hydraulics go into relief as dieselshadow mentioned? Just move your loader joystick all the way in one direction and you should here the tractor grunt. I'd kinda like to know if your system is still making pressure on the implement side.
 

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Discussion Starter #11
Is the tractor making any unusual and strange noises? Can you make the hydraulic system go into relief? You should be able to hear the relief valve lift when you max something out like the loader.
No, the tractor is not making any unusual noise. I can hear the relief valve and tractor grunt a little when I max out the loader.
 

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Discussion Starter #12
I fear that some backpressure may have been created back towards the rockshaft/3PH valve and damaged it, this is the concern when not using PB equipped valves.

When everything was working, and the new valve plumbed in, did the blade see any unusually high forces while operating?
No, I didn't impose any high forces on it. Actually,I hardly even used the hydraulic angle at all while I was plowing for that morning.
 

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Discussion Starter #13
I'm thinking the same thing Kenny. I would also want to check the rock shaft draft feedback control linkage to make sure it's neither disconnected nor jammed.

If the SCV plumbing was causing a restriction the hydraulic fluid may have become overheated and caused a lift piston or spool valve to score or seize. An piston seal or o-ring may have been damaged.
Does the 2720 have rockshaft feedback? I looked but didn't see any.
 

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Discussion Starter #14
Is that the Nortrac 45462? If so, you would have needed to also purchase the optional power beyond plug. Otherwise from what I see you were trying to run the rockshaft on the tank return of the valve.

Can you make the hydraulics go into relief as dieselshadow mentioned? Just move your loader joystick all the way in one direction and you should here the tractor grunt. I'd kinda like to know if your system is still making pressure on the implement side.
Aw crap, yea, that is the valve I ordered. I didn't know I needed that and I saw that as an option when I ordered the valve. What is the purpose of this plug? Sounds like I may have learned a good lesson on hydraulics, unfortunately, the hard way.
The tractor does still grunt when I max out the loader, hopefully that is a good thing.
 

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Discussion Starter #15
Can one of you explain the purpose of this power beyond plug and how it is installed? I was thinking I didn't need it. Apparently, I was wrong. Is there another line that needs to be run back? To where on my tractor?
Thanks in advance.
power beyond plug.jpg
 

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Does the 2720 have rockshaft feedback? I looked but didn't see any.
It doesn't have an external feedback linkage like some of the other tractors have. It does have a Rockshaft Sensitivity adjustment which is somewhat similar to a feedback adjustment. The sensitivity adjustment screw is located on the cover just behind the rate of drop knob.
 

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Can one of you explain the purpose of this power beyond plug and how it is installed? I was thinking I didn't need it. Apparently, I was wrong. Is there another line that needs to be run back? To where on my tractor?
Thanks in advance.
Some links to a few threads explaining this:

http://www.greentractortalk.com/forums/hydraulics/53594-1025r-rear-selective-control-valve-addition.html

http://www.greentractortalk.com/forums/hydraulics/130946-adding-3-spool-valve-2032r-couple-questions.html


Since you said it was not worked hard, I would not have expected any damage though...

This may be a longshot but have you verified the handle is actually moving the valve?

MP40986________UN12MAR08 (1).jpg


ROCKSHAFT CONTROL VALVE LINKAGE
CartkeyPART NO.PART NAMEQTYSERIAL NO.REMARKS
1M803245Knob1
2LVU802644Lever1
319M7139Cap Screw2M8 X 20
412M7065Lock Washer28 mm
5AM879705Lever Kit1(A)
6AM879400Lever1(A)
7AM879711Arm Kit1(A)
8LVA800363Pin Kit1(A)
9AM879709Pin Kit1(A)
10AM879402Control1(A)
CartkeyPART NO.PART NAMEQTYSERIAL NO.REMARKS
11AM879707Shaft Kit1(A)
12......O-Ring1(A)
13M807727Lever1(A)
14AM879396Pressure Relief Valve1(A)
..LVA800359Rockshaft Unit1(INCLUDES PARTS MARKED (A))
..LVA802505Seal Kit1(INCLUDES PARTS MARKED (B))
 

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Discussion Starter #18
Thank you all for the help and input. I did end up taking it in to the dealer after I tried all suggestions. Unfortunately, it ended up being the rockshaft control valve. They had to replace the whole unit because there is not parts for the valve itself. The mechanic surmised that possibly something from my new SCV got into the valve preventing it from working, possibly something during manufacture of the SCV. I learned an expensive lesson. Always make sure all added parts to the hydraulic system should be thoroughly cleaned and inspected before install. I did question him on the use of the SCV without using the power beyond port of the new SCV and he said it should be fine without running a separate line for tank return, but after all your input here, I think I will be adding the return to tank port, just to be on the safe side. Again, thank you all for your input.
 

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