[TowerTalk] Rohn TB-3 Warning

[Gary R. Hosler]

A more basic question would be, is the TB-3/TB-4 designed to relieve
lateral thrust, downward thrust, or both?  Are there any specs for this
product?

de Gary  W0AW




w7ni@teleport.com on 10/28/97 11:31:05 AM

To:   k0gug@juno.com
cc:   towertalk@contesting.com (bcc: Gary R. Hosler/MIPP/Imation)
Subject:  Re: [TowerTalk] Rohn TB-3 Warning




>This may not be what you wanted to hear......but you were lucky.    Those
>thrust bearing centering bolts were not intended to hold the vertical
>weight
>of a steel mast and maybe some beams mounted on the mast.    They are
>simply meant to center the mast inside the "hole" of the thrust bearing.
>
>I have stacks of monobanders mounted on a 24' mast  (14' above the tower)
>I use two muffler clamps above each of the two thrust bearings.   I mount
>them
>one on top of the other facing opposite directions.    The bottom muffler
>clamp then puts the weight of the system onto the thrust bearing.    My
>guess
>is that the weight of the mast and etc could have been  ""released""  at
>any
>time and you could have had major damage or injury.    I 'm glad that did
>not
>happen to you.
>
>73,  Jerry Liley,  K0GUG,  Holts Summit,  Missouri
This is an interesting observation.  As a Rohn Dealer, I have noticed that
those bolts do not seem to be the right type to "bite" into mast and still
keep the threads in good shape.  They are defineitely not "set screw" type
bolts.  I have never seen any mention of any of this in any Rohn
literature,
however.  So, I was wondering how you came to the conclusion that the Rohn
TB3 bolts should not be relied upon to support the mast and antenna weight?
Just your own observation or did you read something from Rohn about this?
I
don't disagree with your conclusion, I just wonder if Rohn ever said
anything about using other clamps above and below the bearings to support
the weight.
Stan  w7ni@teleport.com

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