620 jd hydraulics

[KENWORTH]

hi, i need some help figuring out what happened to my hydraulics on my 620 row crop. i have a #45 j d loader on it. works great. i added a 3 point set up. i started moving the three point lever back and forth, to lower and raise the arms. the engine pulled down hard. every time i tried to lower the loader, it kept raising higher. the 3pt.arms would not lower either. i shut the tractor down and tried to lower the loader and 3 pt. arms, but nothing happened. i disengaged the hydro. pump and then i can lower the loader and the 3 pt. arms. when every is thing lowered and i re-engage the pump everything is fine. when i go to raise the loader, the 3pt. arms begin to raise again, without any input on the 3 pt. lever. the situation returns again. any i deal what is wrong or what happened? thanks so much. bruce

 

[Rusty wheel]

It sounds to me like your problem is in the valving. If the valve doesn"t provide a path for the oil to return to the tank, you"re getting trapped oil in the system. rw

 

[Mike M]

On a 620 the loader and 3pt. rockshaft should not have any effect on one another. Is your lever free on the shaft where they are hooked together ?

Do you have the large spring on the rockshaft arm down to the left hand cast iron support ( elephant ear ) If you don't have this spring and your system isn't worn out the rockshaft will want to go up and stay up even with a 3pt. arms attached.

 

[KENWORTH]

hi guys. i took off the seat/batt.box and took the hydro. cast cover off. pumped the oil out. the linkage all appears to be ok. everything moves and seems to be fine. the piston that goes up and down, that controls the rockershaft is all the way down and appears to be stuck. how free should this be? i wonder if the 3 point not being operated for quite sometime may have caused the piston to bind up some how. maybe the packing/oring got rolled some how. what are you thoughts? the drop adjusting screw is screwed out all the way. would that have anything to with my problem? thank you!!!!!!!!!!!!/bruce

 

[Mike M]

There was a VERY good service manual made on those units SM2022 should be the number.

I'm not quite able to understand what you have going on ?

That piston is to be tight in there as high pressure oil lifts it. It will pull out by hand with something to catch inside of the lip to lift it with,but the suction has to be relieved by removing the rate of drop valve.