Hydraulic filter and cooler placement

[bmklawt]

Long time lurker first time poster, can not find an answer to my question.
This is on a mini excavator, it is my understanding that the return line to the hydraulic tank should ideally be zero PSI but could be up to 100 PSI, does this mean my filter and cooler should be no higher than the return line output on control valve and no lower than the Return line into tank?

 

[Harry in Ky]

That's a confusing question, and why would you be concerned about it? I would expect to see zero AT the tank, but depending on a number of variables the pressure after the last control valve (but before any coolers or filters) would of course be slightly higher. 100 PSI? I rather doubt that. I would think 30 to 50 more likely.

 

[bmklawt]

I was reading on the internet that the return line should ideally be zero PSI but in some cases could be up to 100 PSI, i really have no clue about this.
I was thinking if the return line has no pressure, gravity feed, then all the plumbing the cooler and filter should run down hill from control valve to tank. I guess I would like to know can the cooler and/or filter be above the outlet on control valve or below the tank, will it push the fluid uphill?

 

[Harry in Ky]

I think you're way overthinking this. The system is no doubt capable of 2000+ PSI on the pressure side (when the load requires it) so the return side (again, after the last valve) needs to move oil uphill a few feet if/when necessary to reach the reservoir that's not going to create a problem. After all, it's that same pump pushing the oil isn't it?

 

[WranglerX]

THE pressure on return line to filter and cooler has no relationship as to height/location as to outlet of control valve or height of inlet to tank .... IT will either have pressure or not, pressure is caused by resistance to flow (in the sense-Plumbing) ...There has to be "some" pressure to have flow, but its actually a "free flow" after last work control valve.... Be more concerned about getting good air flow through cooler...