[PSUBS-MAILIST] Rotary oil seal question

[hank pronk via Personal_Submersibles]

Hi Alan,I have used both seals that you mention, I never retained the seals, they are a press fit.  If you go with the low pressure seal first and want to change to the higher pressure seal later, you can just make a bushing to adapt your housing (I had to do that) .  Your enemy is RPM, if I recall your motors run real fast.  For that reason, I would try the low pressure seal first and I would air compensate them, that low pressure seal is perfectly happy at 3,600 RPM.  I have a feeling that high RPM will create a lot of drag in oil and your brushes will struggle to make contact.  I like oil compensating for the ease of it all, but think air compensating is better.  Hankmagnetic couplers is best though 


     On Wednesday, October 14, 2015 9:11 PM, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
   

 Hi,am working away on my brushless thruster.I am looking at 2 different options for rotary oil lip seals on a 10mm shaft.Both are viton one is rated for 6-7psi the other is 145psi.They have different O.D.s so I need to machine for one or the other.I am either oil or air compensating, so the seal will be seeing less than the rated pressure on the low pressure seal.My thoughts are that the H/P seal may give me a bit more longevity if it wears, & acomfort margin. However I am not sure whether the extra pressure on the shaft would be a problem or how much the H/P seal would impede the turning of the shaft.Also I haven't resolved how I am going to fit it. Options are to press fit it externally from the propellerend with or without a circlip to retain it. Or alternatively a bolt on plate to retain it.If I don't go with any form of retaining & rely on the press fit, am I best to glue it in?The other alternative is to fit it from inside the housing against a shoulder, with an internalcirclip retaining it.Any thoughts & opinions on this thanks.Alan
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