LD1
Epic Contributor
Maybe. Did he replace the gland seal? I don't know?
Sorry I didn't put a ? At the end, but you never answered my question at the end of post 57. What do you think his issue was?
Hydraulic Cylinder Leak Down on Box Blade???
- Thread starter Piston
- Start date
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Maybe. Did he replace the gland seal? I don't know?
Sorry I didn't put a ? At the end, but you never answered my question at the end of post 57. What do you think his issue was?
npalen
Elite Member
Something to keep in mind is that a faulty piston seal will create a pressure intensification on the rod side of the cylinder if the weight is trying to retract the cylinder. This higher pressure may cause oil to bypass a valve spool that wouldn't leak much under normal circumstances. Not saying that was the case here, just something to keep in mind.
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LD1
Epic Contributor
Sometimes they come in a cylinder rebuild kit.
wdchyd
Elite Member
Maybe I missed something in this thread but I recall Piston said his box blade was leaking down........in his pics of the unit it shows his cyl is a pull cyl, so that to me would mean his cylinder rod is drifting out when the box blade is "leaking down" (his words)......He never said the cylinder was drifting in (IIRC)
The same setup as most bucket/tilt cylinders on FEL. If the piston seal or a check ball was not pressure tight on the piston head it would drift out like Piston said......so Yes his problem was directly the check/valve ball if it was off the seat......maybe that curl was a piece of a spring that got mashed between the hyd rod and the cyl base
The same setup as most bucket/tilt cylinders on FEL. If the piston seal or a check ball was not pressure tight on the piston head it would drift out like Piston said......so Yes his problem was directly the check/valve ball if it was off the seat......maybe that curl was a piece of a spring that got mashed between the hyd rod and the cyl base
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LD1
Epic Contributor
I thought the same thing too when i watched the video. But post 9 and 10 clear it up better and I think Piston did say somewhere that the cylinder does indeed retract when the rippers drift down.
There is a linkage in there that makes the cylinder retract when the rippers drift down. The cylinder extends to raise the rippers. SO this would be just like loader arms drifting down.
There is a linkage in there that makes the cylinder retract when the rippers drift down. The cylinder extends to raise the rippers. SO this would be just like loader arms drifting down.
wdchyd
Elite Member
Yep, missed that pix......I was thinking it was the top cyl lifting the whole box blade
OP
Piston
Elite Member
Wd,
I did say what you wrote, but I made a mistake. When the scarifier bar would bleed down, the actual cylinder was retracting, so bleeding "in".
On this box blade, in order to raise the scarifier bar, you fully extend the cylinder. And in order to lower the scarifiers for ripping the ground, the cylinder is fully retracted.
I wasn't going to post anymore because this thread seemed to take a turn, but it seemed you were genuine in your reply. Thank you.
npalen
Elite Member
Hydraulic Cylinder Myth - Exploded!
This is some good info on what happens when the piston seal leaks. I realize that a leaking piston seal was not the culprit in this thread but thought some might be interested nonetheless.
This is some good info on what happens when the piston seal leaks. I realize that a leaking piston seal was not the culprit in this thread but thought some might be interested nonetheless.
npalen
Elite Member
True that.
LD1
Epic Contributor
Leaking bypass valves were not causing the cylinder to drift. Just the same as leaking piston seals wont cause it either
muddstopper
Veteran Member
I started to not jump into this, but what the heck. a cyl can drift because of bad seals. I dont care what the video showed. the guy didnt take into account the possible variables. While it is true, that the cyl cant retract because of the rod adding volume to the cyl. The rod can extend, creating a vacuum. Water boils at 212F at sea level. increase altitude decreases pressure. At 10in mercury, water will boil at 192 f and at 29in mercury, water will boil at 32degrees. The same is true for oils, altho the mercury numbers might be different. Now with that said, a cyl carrying a suspended load, should be able to hold that load up to the point of mechanical failure. If there is no way for the oil to escape the cyl, there is no room for movement of the rod. If the seals are bad on the piston, (mechanical failure) it is possible for the oil to bypass from one side of the piston to the opposite side of the piston. While this wouldnt allow the rod to retract, it would allow the rod to extend. If the weight being suspended is great enough, the extending rod would create a vacuum inside the cyl. This vacuum would increase the mercury readings and the oil would boil. The boiling oil would release gas which would expand allowing the cyl to drift, outward. If this occurs often enough, the cyl could create a cushion of air (foaming oil),and allow the cy to extend and retract as the air is compressed and decompressed. This would be a extreme set of circumstances, but to say a cyl cant drift if the oil cant leave the barrel is just wrong.
ovrszd
Epic Contributor
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What's interesting to me in this particular case is the speed at which the cylinder retracted. If it retracted because of an abundance of air in the system wouldn't it have been "bouncy" like sitting on a large rubber air filled ball?? In this case it retracted at an even steady pace until the scarifier was resting on the ground. Then after the bypass holes were plugged it no longer retracted. Still can't quite figure that part out???
Luke'sScreenName
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Yup.
Seems clear that either volume (air or fluid) left the system fairly rapidly OR there was one heck of a vacuum in the system to start OR the syatem is very compliant like a water balloon.
My money is on the first option. :2cents:
LD1
Epic Contributor
Just pointing out that the result would be the same. Never laid claim to what that result would be.
I guess we really don't know what that is yet.
Some of us know what the result will be.
^^^^ This
jenkinsph
Super Star Member
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.
