[PSUBS-MAILIST] air compensation

[vbra676539@aol.com via Personal_Submersibles]

 Brushed DC motors swimming in light (red) Shell dielectric transformer oil.Vance
    On Tuesday, August 1, 2023, 04:03:18 AM EDT, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  
 
  Vance, you just described a modern day submersible well pump, that run for many years.  Did these motors have brushes and what type of oil did they use?Hank
    On Monday, July 31, 2023, 07:09:26 PM MDT, vbra676539 at aol.com via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  
 
  Alan,
Pardon me for butting in, but I can shed at least a little light on this
The HYCO Hymak thrusters were oil compensated, and about as simple as you could get. The nose you see in the pictures is actaally a free flooding fiberglass cap and flange retainer for a Haldex rubber diaphragm screwed down to the forward end of the motor cyleinger. Fill and spill valves were top and bottom about mid-way down the motor housing, and the seals were rudimentary as there was effectively no pressure differential internal to external. No tubing. No seperate bladders. As a side note, the stators were cast in epoxy and machined to tolerance to reduce internal turbulance. Also, the motors were custom wound with square wire, which gave us a very compact 120 volt motor drawing about 50 amps to produce 5 horsepower. And just for base information, this hard-hearted little monster fed straight into a planetary reduction gear set that let us turn that 14 X 14 prop in a Kort nozzle. Very beefy for its day.
You want a little contrast now to then, have a look at the ring thrusters on Pisces VI. They produce 50# more thrust for fewer amps at the same voltage, and weight 17 pounds apiece. The Hymaks weigh over a 100# apiece. Meaning that  the current propulsion system on P6 (4 thrusters, cables, and controllers) all added together weigh less than a single original Hymak thruster.
Vance
    On Monday, July 31, 2023, 05:47:59 PM EDT, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  
 
 Jon, can you describe a reasonable & cheap oil compensation system?All the commercial units & X navy literature describe an over-pressure system that is not easy to build.I would consider the air used in an air compensation system to be minimal compared with blowing your ballast tanks every dive. Scuba systems seem to have very few failures so, that shouldn't be an issue.Alan
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  On Mon, 31 Jul 2023 at 9:36 pm, Jon Wallace via Personal_Submersibles<personal_submersibles at psubs.org> wrote:   _______________________________________________
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