[TowerTalk] question on thrust bearing

[J.Gordon Beattie, Jr., W2TTT]

Alex,
Naw...it will be fine if your mast is going through the top section sleeve.


Thanks & 73,
Gordon Beattie, W2TTT
201.314.6964


-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Alex Malyava
Sent: Wednesday, November 17, 2010 8:13 PM
To: towertalk
Subject: Re: [TowerTalk] question on thrust bearing

Reviving this, 3 years old, subject...

I am about to install 30' of Rohn 25 tower with MQ-26 (5 HF Bands 2 element)
on it rotated by Yaesu G-450.
I understand that antenna itself is pretty light and it will never become
anything bigger than MA5B, so it is an easy job for the rotator..
The top section of tower is "Rohn 25 top section"... I am planning to use 4'
long "military surplus aluminum green mast" for an antenna mast.

How exactly I skip thrust bearing step? Do I just feed antenna mast through
that top pipe and that's it?
Wouldn't it be scratching and squeaking up there?

Thanks,
Alex K2BB




On Thu, Dec 20, 2007 at 12:32 AM, Dino Darling <dino at k6rix.com> wrote:

> A thrust bearing provides two functions...
>
> 1.  Vertical load support (not really the right bearing for this
> application for most thrust bearings).
> 2.  Lateral support (exactly what most thrust bearings were designed to
> do).
>
> The simple answer to your question is NO, as the vertical load of the
> MA5B is minimal.  The lateral support is an advantage and will
> protect the aluminum from long term wear.
>
> If you can afford the bearing, buy it, but its not a "concern" in
> THIS application.
>
> "This is just MY opinion, I could be wrong."
>
> Dino
>
> At 07:08 PM 12/19/2007, Mikemedic130 at aol.com wrote:
>
> >I will be looking to add a cushcraft m5ab mini beam (35lbs, and 3.35sq
> >windload) along with a
> >yaesu g-450a rotor to my 7-40 universal aluminum tower.  Question is
> should I
> >be concerned
> >with using a thrust bearing?  I wont be looking to add anything more
later
> >since I have a small
> >city lot and want to be nice to my neighbors. I currently only have a
> 2meter
> >vertical on the tower now.
> >I guess I am asking do I really need a thrust bearing or not?  Any and
all
> >replies would be appreciated.
> >
> >
> >
> >
> >           Thanks mike kc8unr
> >
> >
> >
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