Loader curl leak down

[CalG]

So how is the valve the problem when the lines are disconnected?

It is a bit of a puzzle as to where the volume of the collapsing ram goes as it slowly enters the cylinder while the bucket uncurls.

Strange that a system that should follow a PV relationship with the fluid building supporting pressure, just "disappears".

That is why we look to the valve, and why the OPs comments regarding no leaks are significant.
Where does the fluid go? Expanding the steel and flex lines?

Of course the cylinders could be sucking air as they extend. That would make the explanation easier. ;-)

 

[lexluther]

I think with the lines disconnected it should act like two separate closed systems one for up and one for down. With no leak it wouldn't budge. The only place for the oil to get from one side to the other and hence move the cylinder is in the cylinder itself.

... I thought it could be sucking air too, but I think it would also be leaking oil on the reverse stroke

 

[Big Wave D]

My L35 was having a similar issue, but not near as dramatic in the speed, at which the bucket was letting down as you're experiencing.

Turns out, that my 25 year old hoses were letting air in, but no fluid out. Now, since I have had to replace 2 because of fluid containment failure - It's made a large difference in resolving my droop issue.

I figure what little let down I still have is likely due to still running off of 2 original hoses on that circuit, maybe/maybe not. Anyway, since they aren't that expensive, I might go ahead and replace both prior to complete failure like the others.

Just my experience. Your issue may be totally internal to the cylinders. Kind of sounds like that to me.

Hope you get things resolved,
B.W.D.

 

[LD1]

It is a bit of a puzzle as to where the volume of the collapsing ram goes as it slowly enters the cylinder while the bucket uncurls.

Strange that a system that should follow a PV relationship with the fluid building supporting pressure, just "disappears".

That is why we look to the valve, and why the OPs comments regarding no leaks are significant.
Where does the fluid go? Expanding the steel and flex lines?

Of course the cylinders could be sucking air as they extend. That would make the explanation easier. ;-)

The rod is pulling out of the cylinder. It sucks air around the gland seal to compensate and/or puts the cylinder under vacuum.....which like air.....acts like a compressible gas.

Curl cylinders drifting is a whole different animal than lift cylinders drifting. With curl, it indeed could be the cylinder or valve. By uncoupling the connectors, it isolates the two and tells you exactly where the problem lies.

The poster that said it was a valve issue, either missed that part in the original post....or doesn't know hydraulics

 

[Rocky J]

It is a bit of a puzzle as to where the volume of the collapsing ram goes as it slowly enters the cylinder while the bucket uncurls.

Strange that a system that should follow a PV relationship with the fluid building supporting pressure, just "disappears".

That is why we look to the valve, and why the OPs comments regarding no leaks are significant.
Where does the fluid go? Expanding the steel and flex lines?

Of course the cylinders could be sucking air as they extend. That would make the explanation easier. ;-)

When the seal that divides the two sides fails there is no up side and down side, they connect and become one with a little restriction . Bypassing around the seal. The seals went bad in the Power Steering cylinder on my Jinma and you had to slowly keep turning the steering wheel to keep it straight. Real pain in road gear meeting a car. Pictures shows the seal fail .

 

[CalG]

When the seal that divides the two sides fails there is no up side and down side, they connect and become one with a little restriction . Bypassing around the seal. The seals went bad in the Power Steering cylinder on my Jinma and you had to slowly keep turning the steering wheel to keep it straight. Real pain in road gear meeting a car. Pictures shows the seal failView attachment 488011View attachment 488012.

Rocky

You still need to account for the ram volume. In or out, plus or minus, there is no free lunch, moving oil from one side of the piston seal to the other is not enough.

Although it's a lot easier to explain when pulling things apart. Every material has a vapor pressure.

 

[kennyd]

It is a bit of a puzzle as to where the volume of the collapsing ram goes as it slowly enters the cylinder while the bucket uncurls.

Strange that a system that should follow a PV relationship with the fluid building supporting pressure, just "disappears".

That is why we look to the valve, and why the OPs comments regarding no leaks are significant.
Where does the fluid go? Expanding the steel and flex lines?

Of course the cylinders could be sucking air as they extend. That would make the explanation easier. ;-)

I understand the logic...but the fact is there are 100's of post's and pictures documenting the fact that when cylinders have bad internal seals, the bucket drifts-did it on my machine once so I have first hand experience.

Also remember that there are two cylinders in parallel in most FEL setups, so that contributes too.

Edited to add:
Here is one such post from a local freind...one 0-ring was torn and the loader wouldn't stay up-rebuilding (in pairs is suggested) fixed it. Sometime real world experience trump's logic and books text's. I can reference more if needed.

http://www.tractorbynet.com/forums/...nders-deere-420-a.html?highlight=#post2314993

 

[CalG]

It can be very difficult to separate science (physics) from magic.

But we can, if we try. An example without an accurate explanation is a poor learning tool.

 

[kennyd]

It can be very difficult to separate science (physics) from magic.

But we can, if we try. An example without an accurate explanation is a poor learning tool.

Ok, I'll be sure to remind Wayne when I see him next that rebuilding the cylinders really didn't fix his problem, the science said so. Oh yeah my loader must still be broken too, darn.

 

[hawkeye08]

Should be a good learning experience replacing the seals. take your time, take some pictures, ask for help when needed.