front bucket dropping overnight

[RickB]

A directional control valve leaking internally won’t be repaired by replacing seals. The spools meter and control flow by sealing directly against the valve body. Some internal leakage is necessary because the parts have clearances so the spool will move in its bore. Excessive leakage will require that hard parts be replaced. Replacing a spool won’t fix wear or a flaw in the valve body.

 

[Lockport]

As per the original question; it's thermaldyamics at work. Once the pressure created by the pump is removed from the equation your hydro oil will "relax"contrary to the illusion that our implement might remain elevated without any system leaks. Maintaining the bucket at height fighting gravity should imply that you've created an authentic perpetual motion machine. Cheers!

 

[jimglassford]

Seals in a valve don't help? I rebuilt the control valve on my John Deere Backhoe front bucket. The seal kit was expensive but it greatly reduced the bucket drop to almost none.

 

[jimglassford]

Lockport,

I am not sure I understand your point and how you call this thermodynamic. The pump pressure creates movement, it does not hold the load. As long as the cylinder is not at either extreme, The pressure in the cylinder should be the same whether the pump is in the loop or not. The pressure in the cylinder is proportional to the load it must support. If the load is constant and the pressure increases, the load would raise to equalize pressure again. I am also lost on the perpetual motion reference. The goal is to create a static system, not dynamic.

 

[LD1]

The only seals I have ever seen in a valve are the o-rings or quad-rings that seal the spools to the casting. That isolates the tank-port passages from atmosphere, and prevents the valve from leaking externally. But does NOTHING to seal the tank port from the work ports. There are NO SEALS for that. As RickB said, Spools seal direct to the casting. Metal on metal. With tolerances in the 0.0001" range. So NO, a bucket leaking down will NOT be solved with simply changing case seals in the valve casting

 

[Diggin It]

Safest answer ...... don't leave the bucket raised. Put everything on the ground before you leave the machine.

 

[RickB]

Safest answer ...... don't leave the bucket raised. Put everything on the ground before you leave the machine.

Winner!

 

[RickB]

Seals in a valve don't help? I rebuilt the control valve on my John Deere Backhoe front bucket. The seal kit was expensive but it greatly reduced the bucket drop to almost none.

Not likely.