FEL wont stay up

[Deere Dude]

Just cycle the loader and bucket several times it will work the air out.

I replaced the seals in my bucket tilt and changed the hyd. oil. For quite a while everything was sluggish and didn't seem to work right. It seemed to me it took many days of using the fel and using the tractor a half hour a day before the sluggishness stopped. Maybe it just needs to work the air out and may take time. That may go beyond reason because I would have thought that moving the cylinder one time would take the air out or driving for 50' would fix it, but that didn't seem to be the case with mine.

 

[stan33]

Brian
For boom to settle lift cylinder piston must move into barrel of cylinder. """""""Where does the extra space come from that cyl rod will occupy that must displace the oil?????""""" If rod seal isn't leaking and control valve is holding a leaking piston seal will not cause FEL boom to settle because there's not sufficient area in cyl bore for trapped oil plus the rod. This principle is the same as a single acting cylinder on a combine platform or Mo-Co lift cyl. as in parts photo only snap ring in single acting cyl acts the same as piston(if packing is leaking) & nut in double acting cyl and just keeps rod from coming out of cyl bore. Piston packing on boom cylinder allows cyl to put down pressure on boom. In parts photo hyd oil pushes cyl rod out of bore but snap ring stops travel when header is lifted.
Thanks,Jim

Are you saying that regardless of whether or not the cylinder seals are leaking, unless either the system after the valve relies on air plus oil to operate the cylinders which would provide some empty space for the rod to collapse into OR the valve is leaking...it only depends on the extent of wear in the valve as to how quickly it will release oil backwards or there would be nowhere for the oil to go even if the cylinder seals are leaking?

I guess that both may be leaking especially given their age. How this will effect the usage of a loaded bucket, I have yet to find out.

 

[stan33]

I replaced the seals in my bucket tilt and changed the hyd. oil. For quite a while everything was sluggish and didn't seem to work right. It seemed to me it took many days of using the fel and using the tractor a half hour a day before the sluggishness stopped. Maybe it just needs to work the air out and may take time. That may go beyond reason because I would have thought that moving the cylinder one time would take the air out or driving for 50' would fix it, but that didn't seem to be the case with mine.

The shouldn't be any air in the system, as the hydraulics have not been opened up yet.

 

[LD1]

3 kinds of cylinders.
Double acting (DA)
Single acting with piston seals and an air space and breather vent on the rod side. Like taking a DA cylinder and only hooking 1 hose to it and putting a breather in the other port.
Single acting displacement type. Uses a packing seal around the rod and a snapring to keep the rod from coming out. TX Jim describes this well in post #17

In a DA cylinder, there is no air and fluid on both sides of the piston. It can NOT compress/retract with bad piston seals alone. It has to be a bad valve, or a leak somewhere for it to move.

In a displacement type SA cylinder, same thing as there are NO piston seals. You simply cannot push a solid steel rod into a cylinder cavity that is full of oil UNLESS that oil has somewhere to go (displace) via a leak or bad valve.

SA cylinder with breather. This type absolutly can retract and oil just gets transfered to the air space on the rod end. Then next extension cycle it will blow out the breather port and is a pretty obvious sign of seal failure. But again, the oil has somewhere to go.

Oil does NOT compress. Unless it has somewhere to go, things just aint gonna move period.

 

[Tx Jim]

Using a SA cyl with bad piston seals, and weight on rod, where do you think the fluid will go.

It will transfer to the air space in the rod end. If you cycle the SA cyl many times with leaking piston seals, fluid will come out the rod side vent hole.

In the parts photo I posted earlier there is no air space or vent for oil to relocate that you speak of.

I bought a used Krone disc cutter this Summer mounted on a Vasser caddy. The cutter bar wouldn't raise straight up(90 degrees). I disassembled lift cylinder and oil was trapped on butt end of cylinder because vent would not let oil on backside of piston out. I cleaned out vent & oil installed new seal kit and now cutter bar raises straight up.

How can a double acting cylinder that has been cycled several times have any air space to allow for relocated oil to occupy from failed piston packing so boom can settle?????????

Now that's my story & I'm sticking to it!!

 

[J_J]

You could be sucking air in your hyd system via a simple little pin hole in suction hose.

Fluid is going to move if there is pressure and a place to go.

 

[stan33]

3 kinds of cylinders.

Any idea what type this is? It has a top and bottom hose and a large nut at the base ( on the underside in this pic).

View attachment 440683

 

[Tx Jim]

Cylinder in photo is double acting type

 

[Tx Jim]

You could be sucking air in your hyd system via a simple little pin hole in suction hose.

Fluid is going to move if there is pressure and a place to go.

But just because a packing seal is leaking on a cylinder does not indicate that fluid has a place to go. If suction hose was leaking and pump was sucking air would not hyd oil be FOAMY????????????

 

[LD1]

Any idea what type this is? It has a top and bottom hose and a large nut at the base ( on the underside in this pic).

View attachment 440683

Yep. Standard DA cylinder.

With no air trapped and no external leaks, if that cylinder is retracting under just the weight of gravity, the valve is the issue