[TowerTalk] installing monster masts in towers(and ? twothrustbearings?)

[JC Smith]

OK, I asked the original question, but as the thread has wandered a bit, let
me throw in .02 here.  The thrust bearing I have on my TX-472MDP is plenty
HD enough to support just about any mast, but the "locking collar" that sits
on top of the bearing only has one small set screw to clamp it to the mast.
It definitely is not designed to support ANY vertical load.  I believe the
THRUST in these radio tower thrust bearings means the lateral force applied
by wind, etc, and not the downward force of gravity.  That's not to say that
some bearings don't support load, but the one that came with this TX-472
sure isn't designed to do it.  I suspect most others we see on towers are
the same way.  Check your rotor specs... I suspect any rotor sized to turn a
particular array will also support its weight.  Mine supports 1800#.  That's
four or five times the load that will be on it.

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com]On Behalf Of Alan NV8A (ex. AB2OS)
Sent: Wednesday, June 08, 2005 7:43 AM
To: towertalk at contesting.com
Cc: David Robbins K1TTT
Subject: Re: [TowerTalk] installing monster masts in towers(and ?
twothrustbearings?)

On 06/08/05 10:04 am Alan NV8A (ex. AB2OS) tossed the following
ingredients into the ever-growing pot of cybersoup:

> On 06/08/05 07:37 am David Robbins K1TTT tossed the following
> ingredients into the ever-growing pot of cybersoup:
>
>
>>>    *Don't rely on the bearing's set screw to support any of the dead
>>>weight of the mast/antenna/coax.
>
>
>>Ummmm, it wouldn't be much of a 'thrust' bearing if the set screws
couldn't
>>hold the weight of the mast.
>
>
> The thrust bearings I have seen are almost capable of supporting a heavy

Oops! I meant " . . . almost *certainly* capable . . ."

Alan


> load, but they had no integral means of clamping the mast: there was a
> separate "collar" secured to the mast by set screws, and this collar
> then rested against the center part of the bearing.
>
> In normal operation, wouldn't the rotator itself support most of the
> downward force?
_______________________________________________

See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.

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