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Re: [PSUBS-MAILIST] RimTec Magnetic Clutches



Hi Byron.
 
You are right. I should have seen it before I asked the question!  What I was thinking was if you put a minnkota motor in a metal or pvc pod and then filled the pod
 
with oil or water that would stop the outside water pressure from trying to get into the pod. What I failed to take into account was that the minnkota motor would still
 
have air inside of it that the outside water pressure would be trying to get to even though the minnkota was surrounded by water INSIDE the pod. So then the outside water pressure
 
would still implode a pod that didn't have very strong walls as you mentioned it couldn't have for the magnetic clutch assembly to work. You definately made sense and I must
 
have been having a blonde moment! Lol. The only way my idea would work would be to first fill the minnkota with transformer oil or the mystery "Jesus water" I have heard mention of,
 
and THEN fill the pod with water. That would work. But there would be no reason to do that. Because once we filled the motor with oil it would be equalized and there would be no need
 
for the pod or the magnetic clutch anymore. I totally see what you mean't. I guess the answer would be to have a strong enough magnetic clutch that would go thru a thick strong pod's walls
 
so the pod could withstand the outside water pressure and as you mentioned 6mm would not be enough wall strength. Perhaps in the future they will come out with a stronger magnetic clutch
 
that would go thru thicker material. Thanks for keeping me straight.
 
Bill.
 
  
----- Original Message -----
Sent: Sunday, October 23, 2005 7:13 PM
Subject: Re: [PSUBS-MAILIST] RimTec Magnetic Clutches

Bill, if I understand what you are thinking...I think I see a  potential problem.   A "waterproof" motor housing still has air inside it.    The motor is not spinning in liquid, right?   But water proof  casings may not be the same as pressure housings. If this is the case, ( no pun intended) then surrounding the motor with  a liquid wouldnt work at any depth greater than that at which the motor housing is rated.   The ambient pressure of the outside water would just be  transferred via the liquid to the motor housing.    It would still flood/leak at the same depth as it would if you just sank it alone. 
 
the method you mention is used by lots of sub people to  pressure compensate external battery banks, to thousands of feet.  They use a flexible membrane on the top of the battery box and fill it with mineral oil.   However, the batteries themselves are liquid filled, and not limited by psi.
 
I hope that  makes sense,  and if  not, then I probably misunderstood in the first  place!
Byron
 
From: Akins
Sent: Sunday, October 23, 2005 7:04 PM
Subject: Re: [PSUBS-MAILIST] RimTec Magnetic Clutches

Hi John.
 
I was wondering if this idea might be practical for your applications.
 
Suspose you rigged your motor to work with the RimTec magnetic clutches.
 
Then suspose you filled the inside of the enclosed casing holding your already waterproof say...minnkota
 
motor with either oil or water before you sealed it. Then when you were at depth, the outside water pressure
 
would not push against the sealed casing holding the motor. Then you would not need a thick
 
barrier between the mag plate and the clutch. Would that work?
 
Bill.
 
 
----- Original Message -----
Sent: Sunday, October 23, 2005 6:04 PM
Subject: Re: [PSUBS-MAILIST] RimTec Magnetic Clutches

Hello fellow Psubbers,

 

I have looked very closely into RimTec magnetic clutches about a year ago. I encourage everyone else to check it out for themselves but I found they were very limited by the type of barrier that one could have between the shaft mag plate and the mag clutch. Less than 6 mm in most cases which was not practical for my application and the pressure I was looking to work with. The barrier has to be non-magnetic of course.

 

There is also a significant limit to the torque they can transmit through a barrier this thick.  Since they are custom made, they are also very expensive. Much more expensive than building a good quality shaft seal. I was very hopeful at first but do not feel they would be successful for a 1 AMT psub. Be sure to check them out for yourself.

 

John

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