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In a message dated 3/27/2010 8:10:29 A.M. Pacific Daylight Time,
vbra676539@aol.com writes:
What creates the oil displacement? The piston rod? And if you are compensating, why go through all the grief to reinforce the housing? With the same pressure inside and out, it seems that the unit would operate normally. Hi Vance. The bellows contracting will create oil displacement. There's a
little more as the rod enters the body but the net effect isn't much as the rod
just fills with oil anyway.
On the fiberglass housing, it's as much to seal the wires as anything else.
The aluminum casing is extruded so has no seams but the little end plates just
have a little paper gasket on them and the rod "bearing" is really just a
plastic or nylon bushing. Not very waterproof. The aluminum casing is about 3/16
inch thick at it's thinnest point so a little extra strength won't hurt. Like I
said, by encasing the body in fiberglass I have a 3/8 inch PVC female
fitting bonded into the fiberglass casing at the end where the wires come out.
This fitting gets a 3/8 inch hose barb fitting screwed into it with the wires
coming through. The hose barb gets a piece of clear vinyl hose and the thru-hull
has the same barb fitting on it. With the epoxy "stop" at the thru-hull, the oil
can't get into the sub.
This makes the whole assembly from the thru-hull to the bellows oil filled.
A small tube leading to a bladder assembly made from a PVC reservoir and a CV
Joint Boot will give the extra oil some where to go, and the CV joint boot will
act as the bladder.
Frank D.
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