Proof that leaking piston seals will not cause a hydraulic cylinder to drift down!

Demonstration video made by Kubota showing that leaking piston seals will not cause a cylinder to drift in the collapsed position (provided there is no external leak).

[@turb0nasty887]

I think your stretching that "myth" ive heard 1000 times. Its refering to the seals that hold the oil in the cylinder. Not sure where you heard it only being the INTERNAL piston seals. But when people in the midwest talk about there bucket leaking down the conversation usually starts with "well there was a puddle under the machine today..." i think you were sly to specifically say piston seals but no single person ive heard out in the field say that has specifically said or been talking about the piston seals.

[@JimMackHeavyEquipment]

I totally agree with you that if there is an external leak, it can leak down. However, in my experience when there is an external leak the complaint is not "my bucket drifts down", instead the complaint is "there is a puddle of oil under my machine". This demo was meant to address the cylinders that drift down without an external leak.

[@alexanderson9171]

Makes sense!

[@johnp3427]

I have a question, will you reply if i ask. Its about a hydraulic cylinder that seems to have pressure on both sides.

[@JimMackHeavyEquipment]

Yes, I will reply. What is the question? Do you think it has leaking piston seals?

[@johnp3427]

Thank you for the reply and the help. I received the top portion of a bucket grapple and mounted it to my tractor. I had to change my 2 spool to a 3 spool to be able to control the grapple. The lift and tilt work fine with the new controls, however the grapple cylinders will either only open and stick or if i switch the quick connect close and stick. If i bleed off the cylinders they will open all the way and close all the way. Then only half way then stop moving. Seems like pressure on both sides of the cylinder. Any help? Suggestions?

[@johnp3427]

@JimMackHeavyEquipment I figured it out, nothing wrong with cylinders, the quick coupler is bad. Bypassed it and everything works fine.

[@JimMackHeavyEquipment]

That is awesome to hear and thanks for sharing the fix. I knew it probably wasn't the cylinder but I was pondering if it could be some type of problem with the auxiliary valve you added. It does makes sense that it was a faulty quick coupler. It was working like a check valve and letting pressure into one side of the cylinder and not letting oil out. Glad you figured it out.