dex3361
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I use a 6 foot rotary cutter and thats about the rate mine drops as well.
Kubota Top N Tilt problem
- Thread starter PSDStu
- Start date
Bird
Epic Contributor
Yeah, I think they'll consider that to be "within specs".
J_J
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I don't believe I have ever heard of anyone doing a bypass test on cyl seals on a cyl.
I think everyone knows that over time cyls will leak down, Some just faster than others.
One just has to assume that the valve is doing it's job of holding the fluid in place, and if it does, and the cyl descends, then the fluid has to be byassing to the other side of the piston.
I also have not seen a chart for leak down rates to classify a leak as acceptable or unacceptable or go /no-go.
Some leaks are based on what one can tolerate from a component.
I have heard about some leak down rates on valves, and I believe it was about 10 drops per minute before the dealer would replace a valve.
Now, is this external or internal leaks. How can one check for an internal leak on a valve? One should be able to measure the volume of fluid from the OUT and PB port.
One could figure out how much a cyl would drop at a particular leak down rate, by computing the volume of the drops in a given time and then compute the movement of the rod when that fluid has been removed from the cyl cavity.
You could also do it backwards, by determining the distance the rod had moved in a certain size cyl.
One can easily see that a certain volume in a small cyl would move the rod more than in a large bore cyl.
The load pulling down on the piston will affect the leak down rate also.
Will a check valve help?
If the leak is from the valve , maybe.
The check can not stop a piston seal bypass leak with a heavy load.
Here is an excerpt from Hydraulic Machinery.
In hydraulic cylinders, cylinder rod drift or creep and the cylinder’s inability to hold the designed load would be identified by increased leakage. The excessive leakage is the result of the fluid bypassing a piston seal either through a worn seal or a worn cylinder barrel (Figure 1).
In spool valves, excessive internal clearances between the spool and the valve body decrease control and stability of the hydraulic circuits and their functions. Profit-robbing energy loss is the result of energized fluid that is allowed to escape back to the reservoir through a spool valve that has an out-of-specification clearance problem. Relief valves or other spring offset valves with a weak spring or a jammed open condition will have the same effect of fluid energy loss by allowing the pressurized fluid to bypass the working circuit.
I think everyone knows that over time cyls will leak down, Some just faster than others.
One just has to assume that the valve is doing it's job of holding the fluid in place, and if it does, and the cyl descends, then the fluid has to be byassing to the other side of the piston.
I also have not seen a chart for leak down rates to classify a leak as acceptable or unacceptable or go /no-go.
Some leaks are based on what one can tolerate from a component.
I have heard about some leak down rates on valves, and I believe it was about 10 drops per minute before the dealer would replace a valve.
Now, is this external or internal leaks. How can one check for an internal leak on a valve? One should be able to measure the volume of fluid from the OUT and PB port.
One could figure out how much a cyl would drop at a particular leak down rate, by computing the volume of the drops in a given time and then compute the movement of the rod when that fluid has been removed from the cyl cavity.
You could also do it backwards, by determining the distance the rod had moved in a certain size cyl.
One can easily see that a certain volume in a small cyl would move the rod more than in a large bore cyl.
The load pulling down on the piston will affect the leak down rate also.
Will a check valve help?
If the leak is from the valve , maybe.
The check can not stop a piston seal bypass leak with a heavy load.
Here is an excerpt from Hydraulic Machinery.
In hydraulic cylinders, cylinder rod drift or creep and the cylinder’s inability to hold the designed load would be identified by increased leakage. The excessive leakage is the result of the fluid bypassing a piston seal either through a worn seal or a worn cylinder barrel (Figure 1).
In spool valves, excessive internal clearances between the spool and the valve body decrease control and stability of the hydraulic circuits and their functions. Profit-robbing energy loss is the result of energized fluid that is allowed to escape back to the reservoir through a spool valve that has an out-of-specification clearance problem. Relief valves or other spring offset valves with a weak spring or a jammed open condition will have the same effect of fluid energy loss by allowing the pressurized fluid to bypass the working circuit.
Last edited:
TripleR
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No, that is I am sure well within specs. Mine was leaking several inches in under an hour, cylinder was rebuilt by dealer. I haven't checked rate lately, but it isn't a big issue.
I don't think 1'' in 4 hours is much to worry about. That is 1/4" a hour, a 1/16'' every 15 minutes. How heavy is your rotary cutter?
You could always chain or strap it to stay in place for rotary cutting.
A sidelink with check valves will not allow for a float function.
You could always chain or strap it to stay in place for rotary cutting.
A sidelink with check valves will not allow for a float function.
npalen
Elite Member
Something to consider when fluid is leaking past the piston seals on a cylinder is there can be a huge increase in psi if the fluid is leaking from the base side of the piston to the rod side. This is true when the cylinder is in compression (being pushed together) This condition can have various detrimental effects on other cylinders and/or valves in the hydraulic system. Cylinders plumbed in series and those plumbed in parallel will be affected differently. It can become a real "head scratcher". I noticed the Kubota in one of the pictures of a related thread has external twin cylinders operating the 3PT as many newer tractors do.
OP
PSDStu
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What I think is happening in my case is that the oil is leaking around the area where the coupling is inserted into the Rear Remote. If it's not seated properly this area will leak internally..... I think this may be what is going on for me.
I have a hydro top link on my JD. Mine has never moved up and down smoothly... I have to tap my joystick button to move it up and down. It's really jerky. The implement usually bounces as I'm moving it. It always stays where I put it but today when using my brush hog, it just "fell down." The rod just dropped out of the cylinder. Are these TnT kits always this finicky?
MtnViewRanch
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All I can say is that the ones on my tractors are as smooth as can be. Sounds like yours is operated with an electric valve? Open or shut. These types of controls tend to be a bit more jumpy. Do you have a flow restrictor on it? That would really help with controlling it.
As far as your rod falling out, sounds like the nut that holds the piston onto the rod came off.
Should be able to take the cylinder end off and put the thing back together again. You know, like Humpty Dumpty.
As far as your rod falling out, sounds like the nut that holds the piston onto the rod came off.
Should be able to take the cylinder end off and put the thing back together again. You know, like Humpty Dumpty. All I can say is that the ones on my tractors are as smooth as can be. Sounds like yours is operated with an electric valve? Open or shut. These types of controls tend to be a bit more jumpy. Do you have a flow restrictor on it? That would really help with controlling it.
As far as your rod falling out, sounds like the nut that holds the piston onto the rod came off.
Yup, is does have an electric valve...open and close. I don't have a flow restricter on it. How do they work and where do they mount?
After the rod fell out, it started working normally. I want to say that happened a while back when I had my brush hog on. Would it ever slip down on its own? Or should I take the cylinder end off?