Implement on 3 point "bounces" when at transport height?

[Sandroost]

When I have my rotary cutter all the way up, it will slowly, almost imperceptibly, lower about an inch or less, then suddenly "catch itself" and go back up abruptly, bouncing the whole tractor just a bit alarmingly. It'll happen about every 7-8 seconds. Doesn't seem to make a huge difference what RPM the engine is spinning, though maybe it is more subtle at higher rpms. Doesn't seem to do it when at cutting height though.
What's up?? New and new to me 574, fwiw.

 

[oldnslo]

Have you tried stopping the lever a little ways before full height to see if 3 point still drifts down? Suspect it will but just a check to see if possibly feed back link is slightly out of adjustment.

Other option is you have an internal leak either on lift piston seals or 3 point valve allowing arms to drift down, position feed back senses out of position so raises back up and cycle repeats.

 

[Sandroost]

oldnslo- yes I did try it on about half way down and it still did it, though the interval may have shortened to 10-11 seconds. And oddly at a lower setting/cutting height I couldn't detect it jumping/dropping/jerking. So it seems the higher it is, the worse it is? Do you think a (dealer installed) third function valve for the grapple that feeds from back there could be implicated?? Grapple works fine FWIW.

 

[3gunr]

When i am going any distance with my cutter on back i lock my 3 pt valve closed so the implement is not bouncing and forcing backpressure into the system, You might check which rear remote your grapple is connected to , One will have a detent , Make sure the lever are in the middle,

 

[oldnslo]

Sandroost
Doubtful 3rd function is having any affect on this.
Sounds like potentially leaking seal on the lift piston for 3 point. When pulsing stops is the rear wheel of the cutter on the ground supporting some of the cutter weight.

Does your tractor have a rate drop control valve for the 3 point. Trying raising the 3 point and closing that valve. This should isolate the leakage to the lift piston seals.

 

[Sandroost]

When it stops bouncing, the rear wheel is still off the ground by about a foot. It does have a rate drop valve, which I'd set to a "slow drop" as opposed to a plop. Next I'll set to a stop up there!

 

[oldnslo]

I reread my previous post and saw that I wrote should isolate vs could isolate cylinder leakage to lift cylinder. Some tractors the rate drop is before the position control so it does isolate the cylinder. I do not know how your tractor is made.

Is this a new tractor or a new to you older tractor? If new don’t turn any wrenches before contacting your dealer since there should be some warranty on this.

 

[LD1]

How many hours?

Different tractor but my MX does the same thing. I have 1300hrs on the clock now.

Its a hydraulic system not unlike any other. Heavy cutter out back, either the cylinder or the valve leaks off a little. Just like a loader or backhoe when raised "can" slowly leak down over time.

The issue with the 3PH is its a position control valve with feedback system.

So its just like driving an old loader tractor where the bucket slowly leaks down and you constantly have to pull the valve to raise it....only with the feedback of the 3PH it does it automatically.

You have two options.....either live with it, or try and isolate it to either the valve or the lift cylinder. And that decision could be made easier if it happens to still be under warranty

 

[oosik]

I bought a brand new Ford 4WD 1700 in 1982. After about ten years or so it started doing the "bouncing thing" when raising/lowering the rear blade. Like it had the jitters.

I stopped the tractor - engine rpm at 2000 - spent 15 minutes or so - raising/lowering the rear blade. As fast as I could make it go. Solved this problem and it never returned. I never had a visible leak in the hydraulic system.

I think there was air in the hydraulic system. Somehow.....

 

[Sandroost]

Tractor has 12 hours on it, so yes definitely still under warranty. The arms will leak down overnight even without a load on them also, which doesn't concern me as much.
Being low on hydraulic fluid or having air in the system crossed my mind as well. Probably ought to at least check the level.
Thanks for the insight, guys.