[TowerTalk] Best mast location? now multiple thrust bearings

[D Calder]

I agree with Steve and have been in the tower business for 20+ years.

Well said, if I don't have enough rotor to hold what I have up there, it's
time to put up something larger that will. I don't use them, won't,
salt air just eats them up over here.

I have seen people go crazy with them and just cause more maintenance in
the end. I use two pieces of 1/4" angle bolted together to hold up masts
to do a rotor swap.

73 Dave n4zkf


-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of K7LXC at aol.com
Sent: Saturday, May 15, 2010 4:54 PM
To: towertalk at contesting.com; jim.thom at telus.net; grants2 at pacbell.net
Subject: Re: [TowerTalk] Best mast location? now muliple thrust bearings

 
In a message dated 5/15/2010 12:01:22 P.M. Pacific Daylight Time,  
towertalk-request at contesting.com writes:

>  For various reasons (some inherent in bearing  manufacturing tolerances) 
three spaced bearings are almost never done in  machinery - it's just too 
hard to get them/keep them aligned.   

And this is in more precision machinery  than you'll ever find in tower 
components. The purpose of the middle "bearing"  is to capture the mast so
that 
you can do a rotator swap on a top-heavy mast  and antenna array. A simple 
plate with a hole in the middle (e.g. AS25G, 45G,  Trylon, etc.) is PLENTY. 
It's not going to go anywhere. Lacking a middle  plate, you can still 
capture the mast with some angle iron and U-bolts. It's  not difficult to 
fabricate and use. 
 
    And I still think that top mounted thrust  bearings are a ham radio old 
wive's tale and not necessary. All you want  to do is hold the mast against 
horizontal wind forces - the vertical forces  can go to the rotator in most 
cases with no problem. 
 
Cheers,
Steve     K7LXC
TOWER TECH -
Professional tower services for hams
and author of UP THE TOWER - The Complete Guide To Tower  Construction
available from _www.championradio.com_ (http://www.championradio.com)  
Cell: 206-890--4188



 
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