>I have had 2 tb-3's at 150' above peru mass for 22 years without touching
> them. At least 4 others also up for periods from 20 to 7 years, never a
> failure here. Never a drop of lube.
Mine was new when it went up. Left it dry. After about 5 years the top race
now sets right down on the bottom race. I haven't had it apart yet to see
what it looks like inside.
Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com
>
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt@arrl.net
> web: http://www.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
>
>
>> -----Original Message-----
>> From: towertalk-bounces@contesting.com [mailto:towertalk-
>> bounces@contesting.com] On Behalf Of K8RI on Tower talk
>> Sent: Saturday, July 08, 2006 02:19
>> To: towertalk
>> Subject: Re: [TowerTalk] Mast and Thrust Bearing questions
>>
>>
>>
>>
>> > Chris: Rule of thumb is 1/3 of the mast inside the tower...it is a
>> > rule
>> > you should follow. Rohn TB3 thrust bearings will last a very long time
>> > if you DONOT lubricate them. If you do, then expect failure. They are
>>
>> Mine lasted about 5 years and it's completely shot. OTOH it was beat to
>> death from having a lot of antennas well above it. When the antenna work
>> is
>> done and the TB-3 replaced (with another TB-3) the top arrays are not
>> going
>> back up. Just the tri-bander and the 7L 6-meter Yagi.
>>
>> > designed to run dry and unless you rotate the beams constantly ie 24
>> > hours a day every day then it should last you a lifetime. It is a good
>> > idea to put a boot on the mast to keep water out of the bearing....look
>> > for a rubber collar in the plumbing section. If you don't have ice
>> > don't worry about it.
>> >
>> > A second lower thrust bearing is a good idea if you ever need to pull
>> > the rotator. It need not be a thrust bearing tho. You want to
>> > eliiminate side movement is all. If you use a second TB3 then do not
>> > tighten the capture nuts except when you are lifting the mast to pull
>> > the rotator. It is almost impossible to get two thrust bearings
>> > aligned
>> > such that there is no twist. Leaving the lower one loose keeps lots of
>> > trouble from happening.
>> >
>> > A second rotator plate with the mast running through the hole and a
>> > piece of oak with a hole drilled about 1/8 inch larger than the mast
>> > and
>> > bolted to the shelf will do the trick for far less money. When you
>> > need
>>
>> That's a good idea. The only things I'd do differently would be to soak
>> the
>> Oak in hot oil for a few hours and to make the hole a "slip fit".
>> What'd
>> really work nice would be to do it in a "pressure cooker" that could be
>> sealed off while it was cooling. This would create a vacuum as it cooled
>> and
>> drive the oil deeper into the Oak when the air was let in. OTOH if you
>> have
>> a wife this might be better done in secret, but she still might wonder
>> why
>> things out of the cooker are now tasting strange.
>>
>> I belive Ash is another good wood for bearings.
>>
>> Roger Halstead (K8RI and ARRL 40 year Life Member)
>> N833R - World's oldest Debonair CD-2
>> www.rogerhalstead.com
>> > to pull the rotator just put a U bolt and saddle on the mast and
>> > resting
>> > on the top of the oak to keep it from slipping down while the rotator
>> > is
>> > out.
>> >
>> > Good luck and do it all safely. 73 bob de w9ge
>> >
>> > Christopher J Galbraith wrote:
>> >
>> > _______________________________________________
>> >
>> >
>> >
>> > _______________________________________________
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>> > TowerTalk@contesting.com
>> > http://lists.contesting.com/mailman/listinfo/towertalk
>> >
>>
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