Hydraulic Cylinder Leak Down on Box Blade???

[LD1]

Is there a reason you won't share that information??

I have many times.

Leaky piston seals would equal the same result as one of those piston valves leaking. That your are correct about.

You are unsure what the results will be....

The piston won't drift (in the retract direction), as a result of either of those scenarios. For the exact same reason that a crossover relief won't work on a DA cylinder

 

[Piston]

You guys are hilarious

Why don't one of you do an experiment? You know, actually prove something? I would, but I really don't care the reasons.

I'm just happy it's all still working perfectly. Didn't drift at all playing in the snow today.

 

[muddstopper]

You already proved it. You rebuilt the cyl and got rid of the air and it started working.

 

[ovrszd]

Since a small shaving was stuck in the piston valve it is feasible that the shaving was holding the valve "cracked open" so the fluid exited through this valve slowly. Air space on the back side of the system allowed this fluid to escape. That is my opinion or gut feeling as to why the cylinder retracted slowly along with simple friction.

Very possible.

 

[ovrszd]

You already proved it. You rebuilt the cyl and got rid of the air and it started working.

Yep...

 

[ovrszd]

I'm just happy it's all still working perfectly. Didn't drift at all playing in the snow today.

Me too.

 

[LD1]

You guys are hilarious

Why don't one of you do an experiment? You know, actually prove something? I would, but I really don't care the reasons.

I'm just happy it's all still working perfectly. Didn't drift at all playing in the snow today.

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Shouldn't have to do an expired the to prove what is already a known and proven fact.

Someone who wants to disprove what is a known and proven fact....The burden of proof is on them.

But even if I attempted an expirement to prove a point, I am sure there will be those that still wouldn't believe. There was a perfect example a few posts ago, where someone linked a computerized model province the same thing I have been saying. What more can be done???

Some don't believe me and many others that a cylinder won't drift....That's fine. But stop spreading the false information as gospel when you clearly don't know.

Take it upon yourselves, to learn something. Take a cylinder and remove the piston seals. (Or even easier, just connect the two ports together after filling with oil.) Then see if you can. Compress the cylinder.

Or...Many are familiar with snow plows. Well,the single acting cylinders are nothing more than a rod with a pair of c-clips to keep the rod from extending out the end of the tube. No piston, no piston seals. Ever try to angle the plow manually with the lines uncoupled? Since there is no piston or seals, shouldn't the oil just freely bypass the keeper rings? And be free to collapse?

 

[LD1]

Yep...

At this point, I still haven't a clue where you stand on this subject.

Sometimes you say some things that I agree with and makes me think you understand, other times not.

 

[ovrszd]

At this point, I still haven't a clue where you stand on this subject.

Sometimes you say some things that I agree with and makes me think you understand, other times not.

I fully understand. I also carefully read posts and base comments on the details offered. Whether those details are fact or not isn't for me to judge. In this case Piston only did one change. He plugged the bypass holes. His drift problem went away. I accept that as fact. Why would he lie about it.

 

[npalen]

This is another article in regard to this thread:
The Root Cause of Hydraulic Cylinder Drift

I replaced the seals in one of the lift cylinders on my FEL several years ago because of an external leak at the gland. I noticed, at the time, that the piston o.d. seals consisted only of a pair of flat rings one on top of the other. There were no o-rings or backup rings like I expected to see. I didn't understand how this would keep the lift cylinders from leaking down fairly fast as it was definitely not a positive seal. The lack of a positive seal on the pistons makes more sense to me now after reading this current thread. Kubota was (is) apparently relying on the valve to prevent/minimize down drift and if the valve has some leakage it won't matter anyway if the piston isn't a positive seal. Make sense?

http://www.tractorbynet.com/forums/hydraulics/266499-cylinder-drift-fel.html

I started a thread regarding this (URL above) which turned out to be very interesting. Post #6 was of particular interest.