Join Date: Jul 2007
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Pressure low or high?
Yes I am talking about bladder pressure, but there is no bladder in the reserve tank, they simply mounted a pony dive tank upside down, so when there is both hydraulic fluid and N2 in the tank the N2 is up above the fluid pushing it down (and out to the cylinder).
I am not sure about high and low pressure. When the keel is down, the hydraulic cylinder is full extended. Which means, I think, that the fluid has been pushed back into the reserve tank and that would raise the pressure of the N2 head. When the keel is retracted the cylinder is compressed (shortest) and is full of hydraulic fluid. So that if the keel should drop, from the raised position, it would have to force the fluid thru the flow control valve back in to the reserve tank. That restriction is what would slow the keel from just dropping freely. It does not stop the keel or help raise it, because it will always bleed away, it just slows it as it drops.
the original owner, 20 years ago, had this installed because he did just as I suggested, ran over a reef that brought the keel up and it dropped on the other side damaging the keel swing pin area and it had to be rebuilt. That all seems fine now (no leaks) and I can avoid the issue by not running over any shallow reef's. But the system does provide another safety feature in that if the raising line should run free and the keel drops fast, someone could get tangled in that line and hurt, much like a heavy anchor line. We certainly take all precautions to avoid this, but this system is installed and I would like it to work. The original owner only recalls that the system had low pressure reading on a gauge (there is a pressure gauge measured in line with the reserve tank).
thanks for your thoughts.