[TowerTalk] Lube a Rohn Thrust Bearing?

[John Brosnahan]

At 05:49 AM 6/14/97 -0600, you wrote:
>Has anyone ever tried lubricating a Rohn TB for a Rohn 45 tower?  

Done it many times--not a problem.  Just a few minutes work.

>I tried to take one apart only to find that many ball bearings appear
>under the only set screw on the inside of the bearing.  It appears as if
>one could squirt some form of grease into that hole and saturate the
>bearing race but hard to tell.  It also appears one needs to remove all
>the ball bearings before the Thrust Bearing truly comes apart.

You figured it out.  Need to remove the set screw and let the little
balls fall out the hole before you can pull the two halves apart.

>The Rohn thrust Bearing has sounded like a metal to metal happening ever
>since I got it.  It does not seem to be a precisions piece of equipment
>but then maybe it doesn't have to be.  Mine worked for 13 years atop the
>tower and it still lookes like it did the day I opened the package.

It is not a precision instrument and the aluminum parts are pretty low tech
and soft.  Colorado weather is pretty kind to them.  Porbably just want
to add some grease in the races before you put it back together.  In any
case, I would take it apart for an inspection just to make sure everything
is OK inside before I would put it back up.

I have been making bearings out of UHMW (ultra high molecular weight)
polyethelene material--fairly cheap to buy--you can saw it to size on a 
table saw and cut a hole in the center with a hole saw.  Never needs 
lubrication and can't rust.  Just drill it out to fit the holes in the top
plate
for the TB-3.  Been running UHMW bearings on an 8L 15M Yagi (60ft boom)
and on the 4L 40M M-squared for many years now with no problems--other
than a minor amount of "checking" due to the high level of UV in Colorado.
Probably be worth the effort to add a top cover over the UHMW to keep it
in the shade!

>Any comments?

Hope this helps.

73  John  W0UN



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