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

To: personal_submersibles@psubs.org

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 -----

From: John Gaertner

To: personal_submersibles@psubs.org

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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