Partial Failure of curl down

[CincyFlyer]

It's not air in the cylinder. All my deeres have done this. Get the bucket where you want it but put some pressure on it. Let off the loader control valve. If you start back dragging, it'll curl up right? Get back on the curl and hold it to curl it down. You'll feel it start to move the tractor. When it'll support the tractor your good to go. I can send you my number and walk you thru it. I'm not doing a good job articulating it but it's very simple. When it stops curling back, stop and do it again. It'll be good to go.

Brett

Yep, it literally cannot be air, or you'd see a bunch of hydraulic fluid all over the place. My bucket sometimes "free falls", and I want to investigate why.

 

[LD1]

It's not air in the cylinder. All my deeres have done this. Get the bucket where you want it but put some pressure on it. Let off the loader control valve. If you start back dragging, it'll curl up right? Get back on the curl and hold it to curl it down. You'll feel it start to move the tractor. When it'll support the tractor your good to go. I can send you my number and walk you thru it. I'm not doing a good job articulating it but it's very simple. When it stops curling back, stop and do it again. It'll be good to go.

Brett

Thats air in the cylinder. No ifs ands or buts. IF the fluid aint leaking out, and the cylinder is still compressing....air is the ONLY possibility. Cause a cylinder full of fluid aint gonna compress.

What you describe, by putting it where you want it, hold it into the ground and stay on the curl til it moves the tractor.....you are purging the air out. Same thing I described by just dumping all the way to the stops and holding it for a few seconds longer. Something has to PHYSICALLY stop the loader from moving. Otherwise its just the air in the cylinder compressing a little bit and moving the loader just like an air cylinder would.

With the bucket physically stopped, the air compresses SO much that its purged out of the cylinder.

 

[LD1]

Yep, it literally cannot be air, or you'd see a bunch of hydraulic fluid all over the place. My bucket sometimes "free falls", and I want to investigate why.

Why would you say its not air. Why do you assume that if there is air in the system that their would be hydraulic fluid all over?

 

[rustyshakelford]

I have 70 hrs on this tractor. Prolly 350-400 on the other ones and they all have done this. It's something with the loader control. Air would be purged out long ago. You have to do this every time you reset the bucket. It's a Deere thing. Wish I knew how to explain it better. Once you know what to do, it's second nature. Something about the curl??? I'm obviously making the explanation sound like it's a in depth thing. Really only take a few seconds to get it going. I'll be home wed morning and will try and take a video

Brett

 

[LD1]

I have 70 hrs on this tractor. Prolly 350-400 on the other ones and they all have done this. It's something with the loader control. Air would be purged out long ago. You have to do this every time you reset the bucket. It's a Deere thing. Wish I knew how to explain it better. Once you know what to do, it's second nature. Something about the curl??? I'm obviously making the explanation sound like it's a in depth thing. Really only take a few seconds to get it going. I'll be home wed morning and will try and take a video

Brett

Everytime you dump, gravity is dumping the bucket faster than it can fill with oil. This sucks air in EVERY time.

ITs not about purging air out from new. Yes its an every time thing. A regen valve would solve that problem. But yes, its air

 

[oldnslo]

LD1 is correct, there is air in the system.

Some people have installed a orifice in the rod end line of the curl cylinders. Correctly sized this reduces the "freefall" and prevents the vacuum / air from entering the blind end of the cylinder.

I installed a counterbalance valve on my Branson since the Counterbalance valve operates on pressure it works under all dumping speeds and conditions.

 

[LD1]

Hydraulics aint rocket science.

Counterbalance valves are used in alot of industrial applications, like large vertical presses. Prevents gravity from wanting to pull down faster than fluid can enter.

Dont know why everyone always things the physics of these things changes magically when you start talking about tractors. Its hydraulics 101.

To illustrate the point.......have you ever used one of them lever action barrel pumps???

Notice how if you go slow and steady that you get alot of flow with each cycle. But if you try to cycle as fast as you can, how each cycle is only pumping out about half of full volume? Especially on an older wore out pump?

Thats because you are physically moving the piston inside the pump faster than it can fill with fluid. Creating an air pocket and that "squishy" feel. And you are only pumping the amount that could enter in the short time.

Same thing with curl. Gravity is physically actuating they cylinder/piston faster than fluid can enter.

Regen would solve this
Counter balance would solve this
A restrictor or flow control on the rod side would solve this
Or just dumping the bucket against a hard stop (edge into the ground or full dump against mechanical stops) and give it a few seconds to purge/fill would solve this.