3pt hitch dropping

[jrschremser]

I posted this in the JD forum and haven't gotten a response. Maybe someone here will provide some info.

THe 3 pt. hitch on my 4600 with 470 hrs. has been dropping and returning. These drop and return cycles occur about every minute or so. The drop is about 1 to 2 inches at the tail wheel on the rotary cutter. It weighs about 850 lbs. There does not appear to be any outward side of damage, bent linkage, etc. I changed the transmission/hydraulic fluid and filter and cleaned the screen at the first 50 hours. I'am about due for the 500 hour service. This is a shuttle shift geared trans tractor.

Any information/suggestions?

 

[Bully]

The hydraulic fluid could be leaking by at the valve or the cylinder. You could have some slop in the adjustment to raise the three point, and it's taking that 1.5 - 2 " to raise. With the three point all the way up, and the tractor turned off, will the mower fall at the same speed? Gary

 

[RoyJackson]

Seems to me there was a post on this a while back...it that case, the tractor was a 4300 or 4310.

The symptoms sure sound like a bad checkvalve.

 

[Soundguy]

I agree with the others.. either an internal leak.. or bad valve / leaky valve.. and you are seeing the circuit regeneration.. It's probably only a 1/4 to 1/2 inch at the arms.. but way out at the end of the mower it is magnified to 1" to 2"...

Soundguy

 

[jrschremser]

THe dealer just picked up the machine for a ROPS recall. After explaning the symptoms to the store manager he said he would call back and let me know the fix. He repeated what you all had suggested as to the cause. He also reminded me, thru their computer records, that I had the machine in for the same problem at 220 hrs. (Getting older and memory doesn't stay at the top sometimes either.) If it is too complicated they will make the repair otherwise I'll do it.
My concern now is if there is metal working around in the system causing stuck valves or damaging seals or o-rings where is it coming from and what other things are going to fail before their time.

 

[jgh]

20051128

And I would certainly plead repeat problem with the dealer (and factory rep if necs) in the likely case you are out of warranty. Many times that will get you some add'l consideration if not a free repair.

Your success there may depend on whether that original 220 hour repair was within the warranty period.

And for those new tractor owners/members out there--this kind of problem is why you NEVER depend on the hydraulic system to hold dangerous weights up for working under--ALWAYS securely block the work in place after raising it.

Jim

 

[jrschremser]

Thanks for the advice on my hitch problem. The local dealer says most likely the rockshaft control valve is the culpret at 470.40 plus labor. Access is from the top once the seat is removed. There goes that new bow I was looking at.