bucket drops

[LD1]

True, it can create a vacuum. But gets progressively harder the more vacuum is reached. and soon an equilibrium will be reached where the drifting stops, or air is pulled in. And with an empty bucket, I wouldnt think there would be enough force to suck air past a good gland seal.

And air getting sucked in is the last thing you want on hydraulics. Air causes erratic behavior, and also will suck in dirt, water and other contaminates.

Still betting its a leaky valve

 

[Tx Jim]

LD1
Thanks for correcting my mistake. This just goes to prove you can teach an "old dog new tricks"
Jim

 

[LD1]

LD1
Thanks for correcting my mistake. This just goes to prove you can teach an "old dog new tricks"
Jim

Thats why we are here.:thumbsup:

 

[kennyd]

Here is a published spec from JD for some older loaders, this is probably what they are using to say it's "withing spec". Mine has done it since new, and most sCUT's and CUT's will to some degree.

 

[mach1rider]

Spoke with service mgr and after long debate on its within specs crap I told him there is a problem with the control valve of this model.
Having all four rams leak down from an internal seal at the same time is not probable.
process of elimination leads to valve problem as the longer I use it the faster it leaks down both tilt and loader.
Just to insure my tests of drop rate and curl are getting quicker with every added hour of use I have been testing it daily after use and logging it.
Talked him into trying it on one of the 3032E on the lot, AND it leaks down.
They are picking it up today for ram testing and most likely a control valve replacement under warranty.
Just a heads up for those who have same trouble.

 

[LD1]

Glad they are gonna fix it for you.

Not sure what "ram" testing they are going to do. ITs a waste of time, the rams arent the issue. But its warranty, so no worries. If it wasnt warranty, And I was paying the bill, I'd be a little upset if they spent time (and charged me) for "testing" the rams.

 

[J_J]

Probably whenever the first hydraulic cylinder was invented.

The piston seals could be completely removed and it still wouldnt drift if the valve is good.

The rod end and base end of the cylinder hold different volumes of fluid. So for a cylinder to collapse, the fluid on the base end is greater than the rod end, and since the fluid dont compress, it has to LEAVE the body of the cylinder via external leak or leaking past the valve. Otherwise NO movement will happen even if piston seals are completely removed.

For whatever reason, this topic has come up many times in the past few months. Leaking piston seals causing a loader boom to drift is a VERY popular but unfounded myth, that many that dont understand hydraulics seem to keep propagating.

If you are a mechanically inclined individual, picture this:

Take a cylinder and totally remove the piston and seals all together. Now re-assemble, fill with oil, and put plugs on the cylinder ports. Do you think you can collapse the rod into the cylinder full of oil?

If you believe you can, where does the oil go that the rod displaces?

Again, this seems to be a popular myth here as of recent, but it is false. For a cylinder to move, oil has to exit or enter the cylinder. It cannot simply just bypass the piston. and the only way to enter and exit is a faulty valve or leaking fitting, or leaky gland, or something else in the hydraulic system not doing what it is supposed to.

There is an exception to your theory, and that is, if there is a pulling load on the cyl it will extend the rod if the seals are leaking. .

Same thing if there is a load pushing on the rod, it will leak down if the seals are leaking.

Either valve or cyl can be tested to verified which one or both are leaking and how much.

To test the valve, just remove the work port hoses and start the tractor. If any fluid comes out the work ports, then the valve spools are leaking.

Your vacuum theory is correct with a good seal. Again, a load is necessary, and the bucket provides the load.

 

[LD1]

Same thing if there is a load pushing on the rod, it will leak down if the seals are leaking.

Assuming you are talking about the piston seals leaking and not a gland/capseal....

Where does the fluid go that the rod displaces as you press it into the cylinder?

Simply bypassing the piston seals dont cut it. There are different volumes of fluid, and the fluid dont compress.

Now if we were talking about an air cylinder I would agree with you. But we are talking about uncompressable hydraulic fluid.

 

[SPYDERLK]

The most a cylinder with piston leak will resist extension is 14+/- PSI times the area of the rod. ... plus seal friction of course.
larry

 

[LD1]

The most a cylinder with piston leak will resist extension is 14+/- PSI times the area of the rod. ... plus seal friction of course.
larry

That is the most it will resist. Once it moves (if at all), unless it sucks more air in from somewhere, the resistance increases as vacuum increases on the cap end of the cylinder.

What is your position on retracting