4720 steering is jerky

[qstott]

I’ve searched and expected to find some answers, but no luck. My JD 4720 cab tractor is a 2008 and now has about 1350 hours. The past few times while using the rear finish mower, I could feel a little jerking at times in the steering. At first it was just occasionally, bit seems to be getting worse. Today I used it for about two hours and it got progressively worse. It was a hot day, around 91 degrees. The a/c was cooling fine and the gauge didn’t show hot. If I turned slowly it didn’t do it as badly, but quick sharp turns was much worse. I think I know what i need to do, but I’m just seeking advice.

 

[LouNY]

I am assuming that you have checked the level of hydraulic fluid and the filters have been changed.
Does your tractor have a dual pump setup with one pump for the steering and a second pump for the remotes and 3 point.
Looking at the specs it appears to have a 5.1 gpm pump for the steering.
Have you checked the pressure of the steering circuit or the flow.
When that occurs with the steering it is normally an interuption of the hydraulic flow to the steering motor.

 

[arlen4720]

I’ve searched and expected to find some answers, but no luck. My JD 4720 cab tractor is a 2008 and now has about 1350 hours. The past few times while using the rear finish mower, I could feel a little jerking at times in the steering. At first it was just occasionally, bit seems to be getting worse. Today I used it for about two hours and it got progressively worse. It was a hot day, around 91 degrees. The a/c was cooling fine and the gauge didn’t show hot. If I turned slowly it didn’t do it as badly, but quick sharp turns was much worse. I think I know what i need to do, but I’m just seeking advice.

There is a sintered metal filter on the pressure side of the power steering circuit. It is on the left side. It often gets overlooked during maintenance. Have a look at that. The operator manual has more info.
Just take it out and clean it up.

 

[qstott]

The owners manual shows an inline hydraulic filter that has a direction of flow arrow on it. Is that the steering pressure side filter? They don’t show a specific steering circuit filter. The fluid level is fine. Thanks!

 

[arlen4720]

The owners manual shows an inline hydraulic filter that has a direction of flow arrow on it. Is that the steering pressure side filter? They don’t show a specific steering circuit filter. The fluid level is fine. Thanks!

Yes, that's the one. I believe the fluid flows from the pump, to the steering valve, then through the oil cooler, then through that filter, then it goes to the eHydro for lube/charge pressure.
If you've never cleaned it, you are certainly due at 1350 hours. I usually do mine every other fluid change or so.
You just take it out, and clean it with some brake parts cleaner. There have been a few cases like yours over the years, and that filter was the culprit. No guarantees though

 

[qstott]

So, if I take this apart, I’m assuming fluid will pour out. Is there a way to get around that? Btw, I was searching for a technical manual as was flabbergasted that one from Deere as $511.00. I found one on ebay in printed form for a little less than $200 and ordered it. I just didn’t trust the $26 one from Russia I could download.

 

[beenthere]

Is this the inline filter you are referring to here?
key # 16.

 

[qstott]

That’s the one!

 

[arlen4720]

So, if I take this apart, I’m assuming fluid will pour out. Is there a way to get around that? Btw, I was searching for a technical manual as was flabbergasted that one from Deere as $511.00. I found one on ebay in printed form for a little less than $200 and ordered it. I just didn’t trust the $26 one from Russia I could download.

you won't lose much fluid, maybe an ounce or two. Once it's off, the filter body comes apart. I might of been able to help you out on the tech manual

 

[qstott]

Thanks!