[PSUBS-MAILIST] Motor modification

Mon Dec 5 16:03:16 EST 2016

Some compensating thoughts.
On James Cameron's sub they used IV drip bags. I am not sure what they were compensating.
These come with various means of hose attachment.
   With regard to the wrap around hose method; I did some calculations on a standard pvc hose, & surprisingly
the colapse pressure was around 100psi. I am sure one of Nuytco's technicians told me they crimped the hose 
that was compensating their lights, to initiate the collapse of the hose for compensation.
   The industry standard for thrusters seems to be around 4psi internal overpressure,
but the compensators they use for this are relatively expensive. Hugh came up with
the novel idea of using a releiving regulator set at 4psi (Parker PR364). Cliff is using this.
This could be used for air or oil compensation.
   The seals need oil for lubrication, & I have read that they can use about a teaspoon a day. Based
on that I would have some sort of reservoir.
   Depending on the motor it may be tricky to get all the air out. If you have a bearing in a bore
followed by a seal, the air / oil would have to move through the bearing which may be a sealed type
or packed with grease. The Minn kotta diagrams I have seen show 2 seals; so how do you get oil or
ambient pressure between those? One will fail when you exceed it's pressure limit.
Alan

      From: James Frankland via Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
 Sent: Tuesday, December 6, 2016 4:44 AM
 Subject: Re: [PSUBS-MAILIST] Motor modification

Hi Antoine\Hank.
Thanks guys.  drinking bladder looks good.  I was thinking of a furniture lift bag, which is very similar.  I use a hot water bottle for the aft motor. Hank, what do you use for a bladder? ThanksJames  
On 5 December 2016 at 13:18, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

James,I put my fill plug under the prop, in the flat end cap,  and it works like a dream. Hank 

    On Monday, December 5, 2016 5:37 AM, Antoine Delafargue via Personal_Submersibles <personal_submersibles at psubs. org> wrote:

 Hi frankI have done something like that for my prop shaft seal oil filled compartment.  But first i removed the hose and filled with a serynge with long steel needle. Then put the tube and filled it with the serynge. The tube is flexible and transparent, from endurance sport platypus drinking bladder
Works wellRegards Antoine 
On Monday, December 5, 2016, James Frankland via Personal_Submersibles <personal_submersibles at psubs. org> wrote:

Hi All I have been talking to Rick about motor compensation which has got me thinking. I originally did my motors like other psubbers have done with the rubber tubes around the sides, but have found them a real pain to fill.  Problem is the location of the tube, plus the tiny bit of protruding pipe nipple on the inside. So, I modified the motors by drilling a hole in the top part of the aluminium endcap and use that now as the vent\final fill.  Its better, but still awkward. I have suggested to Rick this idea, which I am tempted to adopt myself.  Blocking off the existing side mounted pipe nipples and filling\venting\compensating all from the one top hole.  There would be a rubber bulb of some sort on the end of the pipe.  2x pictures show filling and operation.  Appologies for rubbish drawings, im at work. What does everyone think? 

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