Hydraulic top link issues

Kodiak45 · Jan 22, 2017

Take a look at the attached video. My hydraulic top link is floating. Shouldn't this cylinder stay fixed, as that is the primary purpose of it...
https://youtu.be/RHpf12SP8ow /URL]

Kodiak45 · Jan 22, 2017

Top link - YouTube
Not sure if the link posted correctly in tapatalk..

Gordon Gould · Jan 22, 2017

You are right - it shouldn't do that. If you just installed it did you cycle it several times full extend to full retract with weight or opposing force on it in both directions to get all the air out. Air can be compressed and can cause that.

gg

94BULLITT · Jan 22, 2017

Disconnect the hoses from the cylinder and see what it does.

RNeumann · Jan 22, 2017

Gordon Gould said:
You are right - it shouldn't do that. If you just installed it did you cycle it several times full extend to full retract with weight or opposing force on it in both directions to get all the air out. Air can be compressed and can cause that.

gg

Second this post. The very distant second is a problem with the valve....unlikely though based on the way it springs back. It's acting like it's compressing air and springing back.

Kodiak45 · Jan 22, 2017

It must be air. . I did cycle it numerous times, but there still must be some air in there. It started raining on me, so I'll have to play with it tomorrow. I didn't think that disconnecting and reconnecting the hoses would introduce air. To be updated tomorrow.

RNeumann · Jan 22, 2017

Typically the hoses connect to the machine with QDs which shouldn't allow any air.

ovrszd · Jan 22, 2017

Curious to see what the fix is. Don't have a clue. Sorry.

bcp · Jan 22, 2017

The way the rod sort of "springs" out when the implement pressure is off sure makes me think it is air.

Hose connections on the side leave air in the top that can be harder to get out. I would remove the cylinder, turn it with connections up, and work it back and forth 10-20 times. Then re-install and test it again.

Bruce

ovrszd · Jan 22, 2017

Bruce, I agree. Curious to how the air is getting there?

bcp · Jan 22, 2017

New cylinder and hoses may have a quart of air to work out. I just think it isn't all out yet. The oil and air isn't circulating, just going back and forth. It may just take more time.

Bruce

ovrszd · Jan 22, 2017

Possibly. We'll see.

Leejohn · Jan 22, 2017

The best way to get the air out is get cyl all the way end. Then remove rod end hose then run the cyl all the way out. After all the way out just bump the control valve in to fill the unhooked hose with oil.

If you had done that when it was new there would not been any oil in the rod end. Now there is oil in it might get a little messy. You can take the rod quick connect couple then put the hose in a bucket to catch the oil.

MtnViewRanch · Jan 22, 2017

For sure air is the problem. Completely cycle (full strokes) in each direction 10-20 times. If you have a problem after that, then you have a real problem.

LD1 · Jan 22, 2017

^^^^agree. It's just air that hasn't been bled all out yet.

npalen · Jan 23, 2017

I had some issues with air in my top link cylinder and found, after Brian at MtnViewRanch suggested checking, that the weight of the implement was causing the cylinder to extend too fast. The pump was apparently unable to keep up with the demand of the cylinder.
Brian sent me a restrictor fitting which solved the problem for the most part.

Edit: For clarification, trying to get air out of the system by cycling the cylinder "up and down" was seemingly pulling air into the cylinder as the load was dropping too fast.

MtnViewRanch · Jan 23, 2017

npalen said:
I had some issues with air in my top link cylinder and found, after Brian at MtnViewRanch suggested checking, that the weight of the implement was causing the cylinder to extend too fast. The pump was apparently unable to keep up with the demand of the cylinder.
Brian sent me a restrictor fitting which solved the problem for the most part.

Edit: For clarification, trying to get air out of the system by cycling the cylinder "up and down" was seemingly pulling air into the cylinder as the load was dropping too fast.

In reality, the full stroke cycling should be done with zero load on the unit. After a few different situations, what I have found is that over all, it has worked out best to have the flow restrictors on both ports.

Kodiak45 · Jan 24, 2017

Well... I had a few minutes today and I cycled it numerous times and it is still happening. I'll take the cylinder off and try that route

ovrszd · Jan 24, 2017

I've had this problem on my Kubota for four years.

I got a pair of restrictors from Brian and tried them. They slowed my top link movement to the point of causing a slight squeal what activating that valve. Same problem existed.

I thought it might be a problem in the cylinder. But I've been "scolded" for suggesting it's possible for the cylinder to act like that.

Talked to a friend that's a tractor mechanic. He asked me if my "tank" line goes into the tank below the oil level? I don't know if it does or not. He said that's the only place it could be sucking air from.

I've just accepted it.

Curious to hear a solution for yours. Be sure to post any outcome.

MtnViewRanch · Jan 24, 2017

ovrszd said:
I've had this problem on my Kubota for four years.

I got a pair of restrictors from Brian and tried them. They slowed my top link movement to the point of causing a slight squeal what activating that valve. Same problem existed.

I thought it might be a problem in the cylinder. But I've been "scolded" for suggesting it's possible for the cylinder to act like that.

Talked to a friend that's a tractor mechanic. He asked me if my "tank" line goes into the tank below the oil level? I don't know if it does or not. He said that's the only place it could be sucking air from.

I've just accepted it.

Curious to hear a solution for yours. Be sure to post any outcome.

Richard, a couple of things. First, because you don't like how slow the unit worked with the size restrictors I provided, drill them out to .070. Second, did you try feathering the valve at all?

I have had 1 customer that I know of where it took 30 complete cycles to get all the air out of the cylinder and hoses. Typically it should only take 5-10 complete cycles. I have had a few customers where it was 15- 20 complete cycles.

If air is getting in, then something some where is wrong.

When the rod springs back as in the Op's video, that is a vacuum and most likely from the cylinder getting pulled out faster than the oil can get in and will continue to happen until either he starts feathering the control or restrictors are installed, at a minimum of on the rod side of the unit.

These cylinders should be close to rock solid, next to no movement at all, after all they should be full of oil.

On a side note, my top links do move in and out on their own, typically about 1/8" due to the flexing (expansion) of the hoses when additional working pressures are put on the links.