Friction in hydraulic system

[Ranur]

Hi

I need some help on a hydraulic system I´m working on. Im new to world of hydraulics so please keep an open mind
this is a hoisting system with a plunger cylinder and some wire rope sheaves.

We have constant friction in the system that is not depended on the load.
if the load is 130bar the friction is 25bar. If the load is 180bar the friction is still 25bar.

We have looked into all mechanical parts to make sure the problem is not coming from there.
We checked followed the temperature of the cylinder stuffing box and the sheaves as well but saw nothing out of the ordinary.
the alignment of the system is not perfect but not bad enough to explain this friction, and mechanical friction is always directly related to the force, right?

Is it possible the friction comes from the hydraulics? Can a faulty safety valve cause this constant friction?
Or a faulty fitting?

 

[LittleInch]

Please attach a diagram or photos as it is difficult to understand your system.

Please use engineering language.

Load is normally a force, not a pressure.

where are these pressures being measured?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[bimr]

The three main causes of excessive friction in hydraulic systems are:
[ul]
[li] Extremely long lines.[/li]
[li] Numerous bends and fittings or improper bends.[/li]
[li] Excessive velocity from using undersized lines.[/li]

Where are you using to measure the "friction"? Is it possible that the "friction" consists of static head from fluid elevation differences?