Vance,
John Holt use to employ tons of Bimba cylinders on the JSL submersibles. After short time he would just change them out and put new ones in they were so cheap. Corrosion use to get to them real quick (they have stainless steel ones now that probably hold up better).
Have employed Porta-Power and Blackhawk hydraulic systems underwater for a variety of salvage jobs. Would have to have them rebuilt after each time they went in the water due to saltwater intrusion. Then we found Chinese knock-offs that cost less than a rebuild so we would just throw them out at the completion of the job.
Most hydraulic steering units for small boats have double acting cylinders. This means that one side sees pressure and the other doesn’t for them to act. Saltwater intrusion will occur. Can send images of a typical setup and the steering wheel hydraulic unit if anyone that is interested. The powering side usually sees about 800 psi. Many more things here to fail and how do you fit a boat-sized steering wheel into a K-boat? The simple seal for a mechanical linkage steering will be MUCH easier to build and maintain.
R/Jay
Respectfully,
Jay K. Jeffries
Andros Is., Bahamas
It is the mark of an educated mind to be able to entertain a thought without accepting it.
- Aristotle
Good point about the compensator. From my days as a manufacturing engineer (title only - not degreed) I remember Bimba as a supplier of air and hydraulic servo cylinders. You might check them out on the web. I think they can provide very nice tidy cylinders for most applications.
----- Original Message -----
Sent: Saturday, February 17, 2007 8:40 AM
Subject: Re: [PSUBS-MAILIST] through-hulls
Jim, A spring loaded compensator can be installed to raise the internal system pressure above maximum ambient. If we can just find all the parts. Vance
The hydraulic positioner sounds like a good idea. Just keep in mind almost all slave cylinders are designed to hold internal pressure only. You will probably need to create an external seal on the slaves to assure that the water does not infiltrate your system.
----- Original Message -----
Sent: Friday, February 16, 2007 6:14 PM
Subject: Re: [PSUBS-MAILIST] through-hulls
Joe. As I remember, the two way master cylinder ( which would be inside the hull) looked like it had a piston moved either right or left in a tube, and the hydraulic lines on either end of the tube went directly to the positioner ( in our case, outside the hull) and there was no pump.
As far as adapting it for a wet application, it seems to me that the addition of a hydraulic oil reservoir, pressurized to just over ambient, would be enough to keep the water out of the positioner.
You might leak a little oil into the water but clean hydraulic oil isn't a pollutant, and any leakage would be minimal.
As I was e-mailing Vance, I saw this in an old catalogue I had, and I will do a google search to see what I can find. Frank D.
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