Accumulation Grooves

[Brian Coat]

hmm ... That's not a lot of pressure.

Not suggesting either of the following are "the solution" but they may inspire the right solution ...

1) Modern no-weep stern tube seals on boats use radial lip seals, often with some kind of pressure balance port behind, as suggested by GG.

2) Modern water pump seals hardly weep at all despite higher temp/pressures than you need.

Hope this is helpful.

[flynfrog]

[Brian Coat]

I think the illustration above may be an 'old-style' stern gland box with packing bushes.

They certainly work (and I may be wrong here) but I believe they drip?

My understanding is that the pressure balanced type with lip/face seals was developed as an improvement over this type?

As I say, I may well be wrong, I'm only a land lubber!

Anyway, back to F1, eh?!

[PlatinumZealot]

Thanks for the suggestions.
Had looked at packing.. Depending on the final position of the rotor.. (above or below the bearing) the space available will affect this decision.
Still waiting on a reply from NSK and lubron on their self lubricating bearings.

Ok i might create another topic in the projects section for this...

Ok back to accumulation grooves...

[riff_raff]

A good quality commercial lip seal will easily handle a 5 psi pressure delta. And as long as it uses corrosion resistant materials for the case and garter spring, exposure to seawater should not be present a problem. However, what will be an issue is surface corrosion of the mating shaft surface the seal contacts. It should be chrome plated and finish ground for best result. You might also consider using two lip seals in series. The inner seal will keep the grease in place, and the outer seal will keep the seawater out.

Forget packing type shaft seals. They are an obsolete approach.

[Tommy Cookers]

in the days when packing type aka rope type crankshaft seals were common the Matra F1 engine had such a (rope type) seal
because, it was stated, the friction was far less than with the more modern type of seal
iirc 1 hp for rope and 4 hp for the others
though 4 hp seems implausible, it's a lot of heat

since then we seem to have discovered that the Matra engine was BRM-designed below the cylinder head ? and BRM made ???
the early Rover V8s had rope seals (presumably from the Buick design)
a book on modifying the Rover wrongly captioned the photos and made people think their engine had rope when it didn't

[PlatinumZealot]

A good quality commercial lip seal will easily handle a 5 psi pressure delta. And as long as it uses corrosion resistant materials for the case and garter spring, exposure to seawater should not be present a problem. However, what will be an issue is surface corrosion of the mating shaft surface the seal contacts. It should be chrome plated and finish ground for best result. You might also consider using two lip seals in series. The inner seal will keep the grease in place, and the outer seal will keep the seawater out.

Forget packing type shaft seals. They are an obsolete approach.

Ok. Yes.. the lip seals I see just say "steel spring" so I am not sure if its stainless or not.

Double lip seal is something I am definitely considering.

Also considering a plastic bushing. The plastic that was recommended to me is something called Ketron (PEEK) 30% Carbon fibre filled. This bushing should have a good PV value comparable to metal bushings but is self lubricating and low wear and corrosion won't be an issue.

So that is where I am. I like the idea of the plastic because it is less complicated.

I will start the drawings this weekend. Will be doing 2 designs. The ball bearing with seals and then the one with Ketron bushing.

[riff_raff]

You can order a seal like this with both a stainless steel case and garter spring.

http://www.skf.com/iecng/productimage?p ... anguage=en