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Discussion Starter · #1 ·
Working with my 4520 today and lowered the hitch and it stopped working without warning. Checked the cable and shaft that it is connected to on the rockshaft housing and both are working or turning. So it isn't a cable issue, maybe a sheared split pin internally? Anyone else have an issue like this?
 

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Steve:

By chance do you have a Power Beyond kit on your rig? I had something similar happen when the I raised the 3PH and the top-link brushed up against the QD just enough to disengage the connector on the hose. It wasn't immediately noticeable on first glance; but a double check found the loose connector. I plugged it back in tight and all is well.
 

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Discussion Starter · #3 ·
No power beyond circuit on this tractor. Thanks for the suggestion though.
 

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Sorry to hear... is it the rockshaft won't lift, lower or both?
 

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Discussion Starter · #5 ·
It's down and won't come back up, doesn't try to lift at all. Thinking I am going to have to take it apart.
 

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Dang, I was hoping it would be something simple for you Steve.
 

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Discussion Starter · #7 ·
Well I picked up the landplane with the 110 and brought it home yesterday since I can't load both on the trailer if the 3ph won't raise. Will bring the tractor home today and look at it more closely and order the cd for the technical manual. Right now the 820 and 110 will have to substitute for the 4520.

Won't do much of anything until I have the cd but suspect I will have to remove the top of the rockshaft to access the linkage inside. Siince it is out of warranty I will perform the repairs myself.
 

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First would check the feedback linkage on the left rockshaft arm. #29 in first picture. Make sure it isn't broken or disconnected. Then if all linkage on outside of rockshaft is ok, then the control valve is probably at fault. It is # 31 in second picture. Rockshaft housing needs to be removed for access.
 

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I had a similar issue with my 3320, from the drawing posted it isn't identical but I'll offer you my advise anyways. After making sure it wasn't a linkage disconnected or sheared pin I went after the rock shaft valve body. I removed it and blew compressed air in the ports on the tractor side. This should raise the hitch(without load on it of course). So from that point I knew the piston that pushes on the lift arms was ok. In my case I had the PB sintered filter break apart and small pieces ended up lodged in rockshaft valve it self. I was able to take the valve apart and clear the debris. Hope this helps you.

Matt
 

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Discussion Starter · #10 ·
Matt,
Thanks for the reply, with the holidays and work I haven't had a chance to look at it yet. I do think it is very likely to be a linkage issue or valve issue.
 

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Rockshaft issues

I had the same problem with my 955. The Rockshaft would lose all hydraulic pressure and was so loose and floppy as to appear like the shaft was broken. In my case I did rebuild the rockshaft control valve the first time it happened but the real problem was twofold: it was low on hydraulic fluid. The dipstick arrangement on my Deere just does not tell you the amount of hydraulic oil in the system..way too much dipstick tube oil to accurately tell. As it turned out mine was quite low. Secondly I was running a log splitter off the rear hydraulics...this thieved so much oil as to not charge the rockshaft system until all the oil had been utilized by the splitter. You mention nothing about the circumstances related to losing rockshaft lift, so I thought i would throw out there the log splitter issue.
Also are other hydraulics working, like the loader or the power steering? Is this a ehydromatic or manual transmission 4520?
Take lots of digital pix as you tear down, it really helps on re-assembly, which is typically about 2-3 weeks after disassembly, way beyond my short term memory:flag_of_truce:
 

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Discussion Starter · #13 ·
Everything works but the rockshaft on the tractor, no change is sound when the lever is moved back and forth. The lever is operating and turning the shaft that comes out horizontally as it should. The sensor linkage on the left side seems to be okay. The "rate of drop control valve" is set properly but I did check it to be sure.
I am still suspecting the internal linkage came loose somewhere and still intend to take the top housing off to see whats up. Thanks for the suggestions.
 

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Discussion Starter · #14 ·
Thought I would post and let you guys know what the problem was. The two bolts numbered 27 worked loose and fel out. One was laying where I could reach it and I suspect one is in the lower case. Will find my magnetic stick to locate it.

This was a fault of Deere assembly not being tight enough. If you look at the second drawing on page one the bolts numbered 27 are the loose culprits. Not a big deal but two hours work anyeay.

At any rate cheap to fix thank goodness.:thumbup1gif:
 

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Thought I would post and let you guys know what the problem was. The two bolts numbered 27 worked loose and fel out. One was laying where I could reach it and I suspect one is in the lower case. Will find my magnetic stick to locate it.

This was a fault of Deere assembly not being tight enough. If you look at the second drawing on page one the bolts numbered 27 are the loose culprits. Not a big deal but two hours work anyeay.

At any rate cheap to fix thank goodness.:thumbup1gif:
Did you have to pull off the housing to find that? I'm assuming so but thought I would ask.
 

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Discussion Starter · #16 ·
Yes, that was the two hours for the most part. To put it back by myself I applied the gasket to the front half and slid the cover back in place on two pieces of cardboard and lined it up started two bolts at the front. Then raised up the rear, removed the cardboard and applied sealant the rest of the way around. Eased the cover back down and bolted everything in place. Changing out the fluid tomorrow and see how I did.
 

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Yes, that was the two hours for the most part. To put it back by myself I applied the gasket to the front half and slid the cover back in place on two pieces of cardboard and lined it up started two bolts at the front. Then raised up the rear, removed the cardboard and applied sealant the rest of the way around. Eased the cover back down and bolted everything in place. Changing out the fluid tomorrow and see how I did.
That was some really good thinking to do it that way. I will have to remember that if I ever have to do it. Thanks for the good tip.:thumbup1gif:

Let us know how it all goes. By the way did you find the other bolt?
 

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Good work Steve! Glad it was an inexpensive repair! I wonder if this was a fairly common issue?
 

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Discussion Starter · #19 ·
Good work Steve! Glad it was an inexpensive repair! I wonder if this was a fairly common issue?

It worked out okay for me but I shudder to think if the bolts fell out and wedged in the gears it could have been very bad. As far as being a common problem, well it was common for me. Haven't heard of anyone else having this problem though on any of the other forums.

I should mention that having an assortment of 18mm sockets, short 1/2" drive, flex socket and 18mm stubby combination wrench would speed the process up. If I am going to do much mechanical work on this tractor I will have to add a better assortment of metric tools than I currently have.


Rob, if I were to do this again I would make a small slide plate out of tempered masonite with a cleat on the rear end to prevent the masonite from sliding forwards. Still it was easier to reinstall than I anticipated, sometimes you just have to geturdone.
 
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