[PSUBS-MAILIST] Motor modification

Wed Dec 7 16:38:16 EST 2016

Alan,

I am embarrassed to say that I am still not getting this concept. You
mentioned in your email about the clear hose that people wrap around there
Minn-Kota motors and mention about collapse pressure and also mention about
lighting systems. Maybe we are talking about two separate things?
My question was based on wondering about that same clear tubing that wraps
around the motor pods to allow for when the oil gets hot from use and
expands.
Taking any air out of the equation, I got the impression that you could
completely fill a motor with dielectric oil (or any liquid for that matter)
and then take it to any depth and since you basically can't compress a
liquid, there would be no water ingress to the motor (except for the small
space between the two prop shaft 0 rings.) So now when you add a slight
internal increase in pressure from the oil being heated from use, people
use the clear tubing that wraps around the outside of the motor (which is
also 100% filled with the same oil) as a place for the oil to go to expand
rather that spitting out the prop shaft 0 rings. Am I correct so far?
So my question was, the clear hose wall must be flexible enough to allow
for expansion before placing enough pressure on the prop shaft 0 ring to
dislodge? And then if you don't get all the air out of the motor or clear
hose or bladder, don't you have the water pressure trying to compress that
bubble from not only the bladder or tube but past the shaft 0 ring as well?

Rick

On Mon, Dec 5, 2016 at 11:03 AM, Alan James via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> 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?
>
> Thanks
> James
>
> 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
> <personal_submersibles at psubs.org>> wrote:
>
>
> Hi frank
> I 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 well
> Regards
> Antoine
> On Monday, December 5, 2016, James Frankland via Personal_Submersibles <personal_submersibles at psubs.
> org <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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