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-   -   Prop Shaft Packing Gland (http://www.sailnet.com/forums/gear-maintenance/30543-prop-shaft-packing-gland.html)

Alden68 03-21-2007 10:15 PM

Prop Shaft Packing Gland
 
The packing gland/shaft seal on my boat (1968 Alden 32 m/s) has a grease reservoir with a cap threaded onto it. I am assuming that tightening the cap squeezes grease into the gland to slow the rate of water ingress. Does anyone know the proper use of this device (or is it as simple as it sounds) as well as the recommended grease type?

Thanks

sailingdog 03-21-2007 10:19 PM

If this is what I think it is, the cap is for a grease gun nipple, to add grease to the fitting without disassembling it. A photo of it would go a long way to clarifying exactly what you've got.

tigerregis 03-21-2007 10:23 PM

What you've got mr. KIA is a troll named Wilbur Hubbard . He just loves ya.

Alden68 03-21-2007 10:24 PM

The cap is solid i.e. so opening or fitting to insert grease. I had previously removed the cap and dug out the grease in search of a nipple but there was nothing but the open end of a line which ran from the reservoir down to the packing gland. ??? Didn't we send someone to the moon 2 years prior to this being built?

I agree a pic would help and I will get one as soon as possible.

Goodnewsboy 03-22-2007 06:44 AM

You have a fitting called a grease cup. It is both a reservoir and a means of injecting grease into the shaft log. The cap which you turn is meant to protect the grease in the cup and to provide a means to compress it so that it will flow into the shaft log. It allows you to grease the packing without a grease gun.

Properly used, it is a very nice thing. I would keep it full of waterproof grease (boat trailer wheel bearing type) and give the cap a half turn or so every time you put the boat up. It will help to stop the water drip during periods at the mooring or slip and will also keep the shaft well lubricated.

A grease cup should be completely filled with new grease whenever you find that you have turned the cap fully down in the threads and it cannot be turned further. After filling, you should replace the cap, but do not turn it down more than a complete turn or so. You just want to have it contact the new grease so that each future turn will feed some into the log. Each time you turn the cap, the packing gets a little new grease.

These are also found on rudder post bushings where they provide similar "no grease gun" advantages.

sailingdog 03-22-2007 08:55 AM

Cool... thanks for the info... I've seen the grease nipple-type fittings, but haven't really run into what he was describing...

Goodnewsboy 03-22-2007 06:23 PM

One thing I do not think I made sufficiently clear is that when you fill a grease cup, you first remove the cap and then put the new grease into it, not into the fixed half of the cup (It will still be full). When you put the cap back on, grease will start flowing within the first few turns of the cap.

Alden68 03-22-2007 08:12 PM

Ahhhh....thank you. That would make a lot of sense. Well maybe this season I can give my bilge pump the season off!

Goodnewsboy 03-23-2007 08:43 AM

For those interested, here are links that show various grease cups:

http://www.magnetoparts.com/grease_cups.htm
http://www.simrantools.com/lubricati..._cups_nut.html
http://www.lubedevices.com/06701.htm

and even grease selection guidance from Moyer Marine:
http://www.moyermarine.com/faq/6.2.html

sailingdog 03-23-2007 08:49 AM

Thanks for the links GNB.


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