[TowerTalk] Hy-Gain HG70HD thrust bearing

[Ken Alker]

Thanks to everyone for the help and suggestions!  I was pretty convinced 
that there should be some kind of rolling bearing assembly in the gap 
between the bottom of the collar and the "seat" inside the receptacle at 
the top of the tower.  The "inner flange" of the collar sticks down exactly 
0.250" into the receptacle and the seat in the receptacle is 0.450" deep, 
so there is a 0.200" gap just waiting for SOMETHING to be sandwiched 
between the two surfaces.  Perhaps it was put there in anticipation of some 
type of roller bearing assembly, or otherwise.

So, it sounds like this bearing is simply metal on metal, which seems odd 
(is that really a "bearing"?), but upon further inspection I see that the 
mating surfaces are not very sloppy (except that the face of the receptacle 
has been worn a little), and that there is dirt resting on the "seat" of 
the receptacle as if nothing has ever been in there (and no wear marks in 
the horizontals surfaces where a roller bearing would go). I've rebuilt a 
few engines in my day and I recall that the main bearings are 
metal-on-metal (well, there is disposable piece of metal in BETWEEN the 
crank and rod, which is the bearing), so I suppose this makes the 
metal-on-metal scenario more plausible.  Perhaps the types of metal 
involved are of import.  Curious.

In any event, this was my first post and I really appreciate the help, and 
thanks to Steve for hosting the list.  Now I have to let the previous owner 
and her relatives know that I sent them on a wild goose chase.

Ken
KA6KEN

--On Saturday, May 15, 2021 9:59 PM -0700 "kj6y (null)" <kj6y at aol.com> 
wrote:

>
> That is the whole bearing. The collar sits on top of the plate.  Use some
> grease between the collar and plate.
>
>
> Skip, KJ6Y
> 818-522-5421
> Communications Service Co
>
> Sent from my IPad
>
>On May 15, 2021, at 7:56 AM, Ken Alker <ka6ken at alker.net> wrote:
>
>Hi,
>
>I recently acquired a Hy-Gain HG70HD tower.  I hired a crane operator to 
lift the mast/antenna assembly off the tower and then had the tower lifted 
out of the back yard and placed horizontally on a boat trailer to haul it 
away.
>
>When I got home, I removed a "collar" from the mast that appears to be 
what might sit on top of a thrust bearing (or, perhaps, *is* the "top" of 
the thrust bearing assembly).  Here is a picture:
>
>http://www.alker.net/albums/ham-tower-thrust-bearing/IMG_6986.sized.jpg
>
>This collar rested in a "female" circular mating piece that is bolted to a 
plate on the very top of the tower.  See following pictures:
>
>http://www.alker.net/albums/ham-tower-thrust-bearing/IMG_6984.sized.jpg
>http://www.alker.net/albums/ham-tower-thrust-bearing/IMG_6985.sized.jpg
>
>I am assuming there was some kind of bearing "pack" sitting in between the 
collar and the mating surface on the top of the tower that was stuck to the 
bottom of the collar and fell off when the mast was lifted off the tower, 
or it stuck to the mating surface on the top of the tower and fell off when 
we tilted the tower over (or when I drove off).
>
>That said, I'm not totally convinced there was ANY type of bearing between 
these two items.  Maybe they are meant to be lubricated and swivel against 
each other?  I don't think so, but I have no idea, as the manual I found 
doesn't show any pictures of the optional thrust bearing assembly.  There 
is enough space between where the collar sits on the top of the tower, and 
the inner "shelf" mating surface for some type of bearing assembly (I'm 
thinking of the circular exposed, but captured, ball bearings that I found 
in my Schwinn bicycle hub when I disassembled it as a child in the 1970's).
>
>Can someone please enlighten me?  I'd really like to see some pictures!  I 
can't find anything via Google.
>
>If there is a bearing that gets sandwiched between these pieces, does 
anyone know where I can get one?
>
>Thanks!
>Ken, KA6KEN
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