[PSUBS-MAILIST] Minn-Kota Shaft Seals

Mon Apr 10 19:30:32 EDT 2017

Is it possible to drill and port a channel to the inter-seal volume on one of those motors?

Sean

On April 10, 2017 5:12:04 PM MDT, Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>I think this could work Alec and it does fit the KISS principle but I
>don't
>think it an optimum solution.  I like the feed back I got to day from
>the
>Parker seal guy to pull both seals and reset with the inbound set to
>resist
>high internal pressure and the outbound seal set for higher ambient
>pressure and grease  in place of the dead air space.  This is going to
>be
>the arrangement I try next.
>
> I don't have a good feel of how much  differential pressure across a
>backward facing lip would cause it to leak air.  I really think we need
>to
>put one of the Minn-Kota 101 units in a controlled test chamber and try
>out
>some of these variables, test them to depth and then tear them down for
>inspection.  Seem with psubs, there is always one more thing to
>research.
>
>Cliff
>
>On Mon, Apr 10, 2017 at 4:57 PM, Alec Smyth via Personal_Submersibles <
>personal_submersibles at psubs.org> wrote:
>
>> That's a good conundrum. Let's assume the pressure compensation is to
>a
>> very small pressure above ambient (one could also compensate slightly
>below
>> ambient, but I suspect everyone goes above). With the seal in the
>direction
>> to keep water pressure out and in the wrong direction for the
>internal
>> pressure, it could leak air - but the question is how many psi it
>would
>> take for that. On the other hand, if you were below whatever
>threshold that
>> is and there isn't any leak, I actually still like the idea of having
>the
>> seal oriented to keep water out, as it's better than nothing in the
>case of
>> a compensation failure.
>>
>> I still have both seals in and am scheduled to test Shackleton later
>this
>> week. These are going to be very shallow dives, so the air gap
>between
>> seals isn't an issue I've bothered with yet. But I think at the end
>of the
>> day, if all is working well and we've got some dives in, I'm going to
>go
>> ahead and drill the outer seal of one of the thrusters and just see
>if any
>> bubbles escape. My pressure compensation is set at 5 psi over
>ambient. If
>> that turns out to be below the reverse blowout threshold, I like the
>idea
>> of drilled outer seals for its simplicity.
>>
>> Best,
>>
>> Alec
>>
>> On Mon, Apr 10, 2017 at 5:29 PM, Cliff Redus via
>Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>>> Inbound functioning seal will be facing the wrong direction for a
>>> pressure compensated unit if you left the seal set in place that
>comes with
>>> the unit.
>>>
>>> Cliff
>>>
>>> On Mon, Apr 10, 2017 at 3:17 PM, Alec Smyth via
>Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>>> What if we just drill a little hole in the outer seal, and leave it
>in
>>>> place?
>>>>
>>>> Best,
>>>>
>>>> Alec
>>>>
>>>> On Mon, Apr 10, 2017 at 3:11 PM, Alan via Personal_Submersibles <
>>>> personal_submersibles at psubs.org> wrote:
>>>>
>>>>> Jon,
>>>>> just be careful you don't damage the seal seat ( bore) or future
>>>>> seals may leak.
>>>>> You could try threading an over sized bolt in to it & pulling on
>the
>>>>> bolt with a hammer. Maybe hit the bolt in to get it started.
>>>>> You could also heat the housing around the bore first.
>>>>> There is a plethora of tools if you google on image search; but
>>>>> these are on the small size.
>>>>>  I have said before that there is a use to the outer seal as a
>"dust
>>>>> cover" function to keep muck away from the more important inner
>seal.
>>>>> A cheap protective seal that is easy to replace!
>>>>> Alan
>>>>>
>>>>> Sent from my iPad
>>>>>
>>>>> > On 11/04/2017, at 2:32 AM, Jon Wallace via Personal_Submersibles
><
>>>>> personal_submersibles at psubs.org> wrote:
>>>>> >
>>>>> >
>>>>> > Ok, what's the secret here?  Poking around one of my MK101 lower
>>>>> units to get familiar with it and I have hacked up the outer seal
>trying to
>>>>> remove it.  I assumed these things were entirely rubber fabricated
>and just
>>>>> fit tightly into the cylinder that surrounds the shaft.  However,
>it looks
>>>>> like they are rubber over metal and press-fit into the aft section
>of the
>>>>> motor housing.  Anyone removed these things?  I can't find
>anything on the
>>>>> internet with instructions on how to remove them.  I can't just
>pull them
>>>>> out with plyers...tried that and now I'm going to have to purchase
>new
>>>>> seals.   :)
>>>>> >
>>>>> > Jon
>>>>> >
>>>>> >
>>>>> > _______________________________________________
>>>>> > Personal_Submersibles mailing list
>>>>> > Personal_Submersibles at psubs.org
>>>>> > http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Personal_Submersibles mailing list
>>>>> Personal_Submersibles at psubs.org
>>>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Personal_Submersibles mailing list
>>>> Personal_Submersibles at psubs.org
>>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>>>>
>>>>
>>>
>>> _______________________________________________
>>> Personal_Submersibles mailing list
>>> Personal_Submersibles at psubs.org
>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>>>
>>>
>>
>> _______________________________________________
>> Personal_Submersibles mailing list
>> Personal_Submersibles at psubs.org
>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>>
>>
>
>
>------------------------------------------------------------------------
>
>_______________________________________________
>Personal_Submersibles mailing list
>Personal_Submersibles at psubs.org
>http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.whoweb.com/pipermail/personal_submersibles/attachments/20170410/851ae38a/attachment.html>