4720 3rd, 4th & 5th hydraulics

SwLWildcat · Jul 13, 2012

arlen4720 said:
Does it have the "creep to reposition" feature? If so, can you reach through the window to run the loader up and down? I have an open station, I could probably use a stick or something. One thing that disturbed me a little bit after seeing how the hydraulics are plumbed up (on mine), is that it appears that the power beyond will disable ALL rear hydraulics when the hoe is on. I was aways under the impression that the PB was plumbed AFTER the rear SCV's but BEFORE the rockshaft. It actually is BEFORE all of it. I thought it would be nice if the grapple would still work at least (3rd EH SCV). I could see wanting to dig up a stump, then carry it off with the loader/grapple.
How is yours plumbed? Mine is: Pump, PTO clutch, Mid SCV, PB, 4th & 5th Lever SCV's, 3rd EH SCV, then Rock Shaft.

I had the creep to reposition feature but I returned it before I installed it. I ran another one with that feature and it was a bit of a pain. I found it was just easier to hop off and move the machine. You can't open the rear window when your sitting on the backhoe. It might be OK with a cabless model... You are correct on the plumbing, and mine is currently that way as well, but I am going to change it. I am going to put it all back in series as if the PB/485 is just like another valve bank. This will allow the 3 & 4/5 valves to work. They are just dumping the oil back to sump after it goes through the 485, but I am going to route the return oil back to the other valves. I did start to build a thumb today. This is what I have so far. I also ordered up a hydraulic cylinder which should be here this weekend.

arlen4720 · Jul 13, 2012

SwLWildcat said:
I had the creep to reposition feature but I returned it before I installed it. I ran another one with that feature and it was a bit of a pain. I found it was just easier to hop off and move the machine. You can't open the rear window when your sitting on the backhoe. It might be OK with a cabless model... You are correct on the plumbing, and mine is currently that way as well, but I am going to change it. I am going to put it all back in series as if the PB/485 is just like another valve bank. This will allow the 3 & 4/5 valves to work. They are just dumping the oil back to sump after it goes through the 485, but I am going to route the return oil back to the other valves. I did start to build a thumb today. This is what I have so far. I also ordered up a hydraulic cylinder which should be here this weekend.View attachment 273147 View attachment 273148 View attachment 273149

I would think it would be better to replumb the location of the PB loop, to put it after the 3rd SCV and before the rockshaft. Then, the rockshaft would be disabled, AND you would still have the unrestricted dump back to the tank.
Are you going to put a relief valve on the thumb so it will have "give" when bearing down on it with the bucket? Just curious if that's an issue.

SwLWildcat · Jul 13, 2012

There are a lot of steel lines to do that... I don't think it will be an issue to let the oil go back to the rock shafts...? Once the 485 is on and the rock shafts are up I just leave them up all the way anyway. I guess I could soft hose the PB in after the 3rd as well, or better yet after the 3, and the 4/5. Then I could still use all 3 if needed.

I will check pressures once I have the thumb installed. I may need to pull the plug on the dump side of the bucket section and pop in a relief. I'll tee in a gauge on the bucket and see what happens, as well as on the thumb cylinder.

JD 4520 · Oct 8, 2012

I have a 2006 JD 4520 with the 3rd function. What is the best way to add a 4th & 5th function?

Furu · Oct 14, 2012

You can obviously do the JD kit for 4th/5th SCV or you can do a modification on your own which I did. Unfortunately on this not so smart phone I do not know how to give you a link. I will repost when I have access to a real computer. Post is titled adding additional hydraulic control valves.

JD 4520 · Oct 14, 2012

Thanks I shall do some checking.

Furu · Oct 15, 2012

Furu said:
You can obviously do the JD kit for 4th/5th SCV or you can do a modification on your own which I did. Unfortunately on this not so smart phone I do not know how to give you a link. I will repost when I have access to a real computer. Post is titled adding additional hydraulic control valves.

Here is a direct link to the thread. http://www.tractorbynet.com/forums/hydraulics/260184-adding-multiple-hydraulic-control-valves.html

We have the same or close year model on our 4x20 models.

jloven · Dec 12, 2022

jd110, I know it s a long shot, but do you have a similar hydraulic diagram for the 4720 open station?

I already have the 3rd SCV and PB kits installed on my 2013 open station 4720. I picked up the LVA26037 kit for the 4th and 5th last weekend. Tried to hook it up last night, but the oil lines in the kit don't line up. The line going from the 4th / 5th scv to the control valve already has a line that feeds the PB loop. Am I missing a hardline and if so, where does it go? Is it LVA17082? Do I need LVA16839 as well?
Thanks