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[TowerTalk] Stacking 105CA & 155CA on T2X rotator

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Subject: [TowerTalk] Stacking 105CA & 155CA on T2X rotator
From: (Pete Smith)
Date: Tue, 09 Mar 1999 15:00:30 +0000
At 04:59 PM 3/8/99 -0500, Mark wrote:
>A muffler clamp? I don't understand. Is a muffler clamp designed to do
>what a thrust bearing has been doing all these years ? I guess my
>installer ripped me off for another hundred bucks. Shame on me for
>listening to a professional. I didn't mean that all the weight was
>removed by having the two, but I guess I have just been lucky that's

Hey Mark, I wrote to you privately, but since you copied the reflector I've
done the same.  (For other readers, my suggestion was that an accessory
shelf and muffler clamp on the mast could accomplish the same maintenance
benefit as a second thrust bearing, by allowing the mast to be jacked up
and still held securely when rotator maintenance is needed).

 The muffler clamp just holds the mast up off the rotor so you can pull it
out, once it has been blocked up off the rotator top.  It's removed once
the system is operational again.  For that matter, my pointy-top has a
tapped hole for a set-bolt to accomplish the same thing.  My professional
(a ham, who regards anything under 300 feet as a "small tower") argued
against thrust bearings as an unnecessary expense.  Subsequently, on this
reflector, others have noted that some rotators are specced for a certain
minimum amount of weight to preload the bearings properly.

Properly installed, a thrust bearing takes all the weight on the vertical
shaft passing through it, or else it's not acting as a thrust bearing.  If
you let the weight rest on the rotator and then tighten the bearing on the
mast, all you have is an expensive sleeve bearing.  I'm not saying that
your installer ripped you off, only that he may have been working on the
basis of some folklore that resulted in some unnecessary expense. 

73, Pete Smith N4ZR 

Loud is.

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