IO540 :
Quote:
pressures in the 6000psi region are common in hydraulic machinery.
Very true; however the 6000psi is not present 24/7 for 2 years, and it is not present anyway without leaks. Leaks are common (which is why the fluid needs topping up periodically) and are ignored unless significant.
The vast majority of hydraulics are pressurised transiently.
I would -much- prefer to design a system that had a static 6000psi pressure than one with dynamic pressures.
Think about the postulated O ring, with static pressure it will deform once at get squished (technical term that) into all the tiny bumps and nicks.
With a dynamic load it will have to do this many times, each cycle will result in (very tiny) degradation, with microscopic amounts of salt water getting a bit farther in each time.
BTW: There are many methods other than O rings to seal something that does not require frequent, if any, access.
Lastly on leaky hydraulics: Most of the leaks are at sliding seals, if you think sealing an enclosure is hard ponder a shiny rod moving in and out past the seal.
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For BearFoil and others on the search process:
I usually find things in the last place I look, of course if you keep on looking after you find it your mental status may be in question.
Looking back it is easy to see a better way but overall I would say a fairly rational plan.
There could have been different even better plans but it is important to have a single coherent plan.