For safety's sake ... a quality clamp (muffler type) very slightly above the
top --or for that matter, the one in the tower on its mounting plate
..thrust bearing will address that issue...
as to the come along, I use a pulley at the top, and run the line for
raising the mast from the tie-off at the tower bottom up and over the pulley
at the top .. then the raising "umphh" is addressed by the ground crew. I
inserted a large correct size pulley (upside down) in the bottom of the
mast --plan ahead, put the mast into the tower BEFORE you erect the whole
enchilada...
The advantage to this method is that you can install the beam/s/?? as the
mast is raised above the tower. Again, using a clamp on the tower for
safety ain't a half bad plan. Of course, super heavy arrays may not be
able to done this way .....
When all is in place, and the safety clamp above the top bearing is
tightened, you can simply put the rotator mounting plate and rotator in
place... worky worky .... YMMV.
Mark Nelson - AA6DX
mailto: AA6DX@ARRL.NET
----- Original Message -----
From: "Phil Camera" <kb9cry@comcast.net>
To: <towertalk@contesting.com>
Sent: Wednesday, February 21, 2007 9:21 AM
Subject: [TowerTalk] Thrust Bearing Screws & Fingers
If you are putting the second thrust bearing in so it can be run loose and
only tightened when you need to pull the rotor for maintenance that would be
O.K.
Excuse me, so you're going to depend on six little screws (three at the top
bearing and three at this second bearing) using friction binding into the
mast material to be strong enough to hold up any mast and the weight of the
antennas up above from slipping down and smashing your hands/fingers?
Not me. Those bearing screws are only designed to hold the mast in the
center of the bearing, not to keep it from slipping down.
What I do is take up two pieces of uni-strut or angle iron with a large pipe
clamp in the middle and attach these to the mast and extend the ends through
the tower rungs and allow those two to hold up the mast. Or on another
tower I attach a large mast clamp and use a come-a-long rigged internally to
pull up and hold the mast/antenna assembly.
I wouldn't want to chance what you're planning.
JMHO (and I like my fingers).
Phil KB9CRY
_______________________________________________
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|