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Re: [TowerTalk] TB3 Thrust Bearing Binding

Subject: Re: [TowerTalk] TB3 Thrust Bearing Binding
From: "Roger (K8RI) on TT" <>
Date: Fri, 31 Jul 2015 02:22:46 -0400
List-post: <">>
What material is the mast? If it's Al the expansion may cause binding with the mast pushing up. I believe you said the second bearing was used only for removing the rotator.

With 2 TB3s tight on an Al shaft they could be pushing against each other. Normally the bottom bearing would have the bolts locked with them just touching the mast. The Ham series including the tail twister are designed to run with a positive load.

The problem could be the rotator, or bearings.  Lots of choices.


Roger (K8RI)

On 7/30/2015 5:17 PM, Kenneth Goodwin wrote:
 From all indications with the outside temps reaching 100 degrees F, one or
both of my two TB3 thrust bearings seems to be binding.  All TX2 Tailtwister
rotator electrical data measured from the ground matches my baseline
(resistance), I can hear and feel the brake release and the voltages applied
to the TX2 motor windings are normal but until this morning when it got into
the 80's - it wouldn't budge at all.  I use one thrust bearing on the top
platform and a second as a means to remove the rotator if ever needed and
keep the tangential loads off of the TX2 rotator.  I believe this happened
the day before and it was in the same position (332 degrees).  Usually when
the 40 meter beam fails to rotate, the TX2 brake mechanism is binding even
with the Green Heron RT-21 rotation algorithm (small rotation the wrong way
before rotation to the commanded setting).  Is heat a feasible failure
mechanism for a Rohn TB3?   Anybody else ever run into this problem?  Ken

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