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Re: [TowerTalk] US Tower Crank-Up Tower Thrust Bearing

To: towertalk@contesting.com
Subject: Re: [TowerTalk] US Tower Crank-Up Tower Thrust Bearing
From: Mac <libbysales@austin.rr.com>
Date: Sun, 28 Jul 2019 16:30:55 -0500
List-post: <mailto:towertalk@contesting.com>
That was not enough answer,  ok so you know the thrust bearing ID  now you need your mast to closely match this size 2-1/16" size.  A 2" od mast is not really acceptable, if you still have the eccentric collar presuming this bearing is eccentric, the collar can be hand fitted to the bearing and then locked with the set screw. For ham applications this works, due to the limited rotation speed, but in the real mechanical world using eccentric bearings and collars are most often intended for one direction only.

Another list member has offered he shimmed his mast to make up the difference, that is not how i was taught or shown the 1/16" difference is to be accommodated, the difference should be made up for by the bearing proper being eccentric whereby using a perfectly round collar will find the small misalignment point and most often rest in that position, but at our rotation speeds it is a small point of significance, but to shim the difference is not normally the preferred or acceptable technique, using a bigger OD mast is. Or of course a smaller ID bearing

Its a crap shoot, all 2" pipe is not equal, but presumed you have a non 2" galvanized mast then have it galvanized, your 2" od mast just grew in OD size by some thickness of the galvanizing process and how many times it might or might not have been dipped.

I am sure a better answer will be proffered by someone here and it will make perfect sense to you.

mac/mc  w5mc

On 7/28/2019 4:02 PM, Mac wrote:
This measurement is near insignificant, it needs or should comport with the mast size O.D. not all mast are equal in size by a long shot.

By its self is not enuff answer.  The mast and thrust bearing are near symbiotic in their relationship.

best:  mac/mc  w5mc

On 7/28/2019 1:06 PM, W3OA wrote:
A buddy and I are doing some work on a US Tower crank-up with an unknown history.  He measured the inside diameter of the thrust bearing as 2 1/16 inches.  Does this sound right or is it possible the bearing has been replaced with one that is not the same size as the original?

73 - Dick, W3OA

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