builtin check-valves in directional valves - sufficient for top&tilt drift?

[orangetree]

Many directional valves advertise built-in load checks. Are these as effective as the standard double-pilot operated check valve typically hard-lined directly to the cylinder of top & tilts?

Obviously putting the check at the directional valve will introduce a minor amount of bounce to the system (elasticity of the lines) - but that would be moot (or a positive as it absorbs & reduces peak loads); this isn't eactly a precision system.

But if the built-in checks are quality poppet one-way valves, we don't need to extra DPOCV, right? I'm thinking about Summit's monoblock valves in particular.

Thanks!

 

[oldnslo]

Yup Load checks are not in the work ports but are in the valve to prevent flow from load back into the pressure lines. Long way of saying they will not prevent cylinders from drifting due to valve leakage.

Some special valves do have work port checks but these are common.

 

[orangetree]

Yup Load checks are not in the work ports but are in the valve to prevent flow from load back into the pressure lines. Long way of saying they will not prevent cylinders from drifting due to valve leakage.

Some special valves do have work port checks but these are common.

Interesting, i read it the opposite, need to call in:

From Monoblock Hydraulic Directional Control Valve, 1 Spool, 11 GPM
> Anti-drop load checks on each spool

Maybe "drop" here is referencing mkre of safety "if this cheap valve fails with engine off, load cant free-fall"?

 

[oldnslo]

If you look at the valve schematic and it shows the check valves in the pressure lines. This prevents the load from dropping when you are trying to feather the control and lift very slowly.

 

[orangetree]

If you look at the valve schematic and it shows the check valves in the pressure lines. This prevents the load from dropping when you are trying to feather the control and lift very slowly.

Ah you are right. They are tiny with no boxes drawn around them, i looked, and completely missed. Thats pretty definitive.

Now, for the betting pool on ratio of:
- days to get an informed answer on TBN
- days to get the same from the oem/vendor

thanks for your help!

 

[Tinhack]

But if the built-in checks are quality poppet one-way valves, we don't need to extra DPOCV, right?

Wrong. Tell me what you think will happen in the valve if a hose or connector fails. The cylinder will drop if the failure is on the high-pressure side. That won't happen with pilot operated check valves. The pressure is contained in the cylinder.

 

[orangetree]

Wrong. Tell me what you think will happen in the valve if a hose or connector fails. The cylinder will drop if the failure is on the high-pressure side. That won't happen with pilot operated check valves. The pressure is contained in the cylinder.

what you're referencing is not relevant to my question, which per the title is specifically about drift.

It is also of questionable relevance to the rear hydraulics in general - having nothing to do with why the DPOCV is commonly spec'd on top&tilt cylinders - but since I didn't ask that I see no point in debating it here.