[TowerTalk] refurbish a Thrust bearing ?

[Guy Olinger, K2AV]

From: T A RUSSELL <n4kg@juno.com>
Subject: Re: [TowerTalk] refurbish a Thrust bearing ?


>
>Yes,  TWO bearings relieves the rotor of the undesirable
>side forces.  That is the way to go for a tall mast above
>the tower.  With a short mast and a single antenna,
>it is overkill but won't hurt anything.
>
>

There are some complications if you do this, especially if your thrust
bearings are fairly tight (very little side-to-side play).

*Without* the lower thrust bearing, and the rotator down a ways from the top
bearing, there are two adjustments where approximate adjustments (+/- 1/4
inch slop) are ok.

1) whether the rotating center of the mast is shimmed out to coincide with
the exact rotating center of the rotator.

2) whether the rotatating center of the rotator is dead center under the
upper bearing.

With the lower bearing in the picture, the system will not tolerate the mast
at the bottom traveling in a small loop because it's not centered over the
rotator. Unless you have the "matching" pipe size, you will have to shim the
mast, so that it only rotates, not oscillates, when the rotator turns.
Further you will then have to have a variable rotator mounting scheme to
place the rotator in the exact horizontal spot now dictated by the two upper
bearings.

Further, as described in quite a few earlier posts, it appears that the
bearing races were designed to be optimally employed with the vertical
weight loads specified by the manufacturer. Although noone quoted a
manufacturer's statement, this certainly appeared the case in times I have
had mine apart.

The great use of the lower bearing is for removal of the rotator. But I
would leave it unstressed when the rotator is in the system.

73, Guy.
Guy L. Olinger
k2av@qsl.net
Apex, NC, USA



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