[TowerTalk] installing monster masts in towers(and ?twothrustbearings)

[Kirk]

Dick,

This is a good point and one that I've also thought about.  I've just
purchase the mast raising fixture (MRF) for my TX472.  I have a top
thrust bearing but am wondering if I need another thrust bearing near
the rotator?  As you point out Dick, this will keep the mast centered
while rising.  I hate to purchase another thrust bearing and bearing
mount just to keep the mast stable while it's being raised into
position.  Is there any less costly way to accomplish and maintain mast
stability?  The mast I'm using is 20 feet in length and near the top of
the mast will be the STEPPIR four element.  Lots of weight to control
while the mast is being raised and then lowered onto the Orion rotator!!

Kirk, K6KAR
Niceville, FL


-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Dick Green WC1M
Sent: Saturday, June 11, 2005 2:08 AM
To: K7LXC at aol.com; towertalk at contesting.com; jerry at k0tv.com
Subject: Re: [TowerTalk] installing monster masts in towers(and
?twothrustbearings)

I'm a total novice at this, so pardon the dumb question. I can see where
the
middle thrust bearing adds no value and may be more trouble than it's
worth,
but isn't a middle bearing shelf useful for when you need to remove the
rotor for repair? I would think it better to have a collar around the
mast
in two places (top and middle plate) to keep it from wobbling around as
you
raise it. Also, with a middle plate you can distribute the weight of the
mast between two plates while the rotor is removed (using muffler
clamps, of
course.) Does this make any sense?

73, Dick WC1M

> -----Original Message-----
> From: K7LXC at aol.com [mailto:K7LXC at aol.com] 
> Sent: Friday, June 10, 2005 1:31 AM
> To: towertalk at contesting.com; jerry at k0tv.com
> Subject: Re: [TowerTalk] installing monster masts in 
> towers(and ? twothrustbearings)
> 
> 
> In a message dated 6/8/2005 7:29:19 PM Pacific Daylight Time, 
> towertalk-request at contesting.com writes:
> 
> 
> >  Thrust bearings normally only need to handle side to side 
> forces. The
> rotors
> can bear the weight of the antenna(s) and mast with no 
> problem. KC1XX tells me that the locking bolts should all be 
> removed from thrust bearings. Let the rotor hold the vertical 
> load and let the thrust bearings take the horizontal. My 
> thrust bearings have no locking bolts whatsoever. No 
> problems. When I need to take the rotor out, I put some U 
> bolts on the mast.
> 
>     Amen to that, brother. My personal opinion is that mast 
> vertical thrust 
> bearings are highly over-rated and don't really contribute 
> anything of value to 
> the rotating system other than a being a nice mast bushing. 
> 
>     IMO the amateur need for a special thrust bearing is sort 
> of like the 
> amateur perceived need for use of  the 1-foot long "torque 
> arms" that hams have 
> put great value in for decades but in reality add little or 
> nothing by its use. 
> (The Great Ham Radio Urban Legends?!?)
> 
>     Rotators are designed to have some preload on them and 
> their bearings. 
> Why do you think all those bearings are there in the first 
> place?!? The T2X has 
> NINETY-SIX of them. 
> 
>     For the reasons posted previously, a mid thrust bearing 
> is just a total 
> waste of money. (Unless you really did need that expensive 
> bushing - hi.)
> 
>     People SCREW UP bearings in different ways. If they'd 
> have just left them 
> off, they'd have been in better shape! And that's not 
> speaking to the bind 
> that can be easily introduced to the rotating system. And I 
> take my hard-hat off 
> to anyone who can measure 0.01" with an instrument on top of 
> a tower. Both of 
> you. 
> 
>     And don't get me started about the yucky eccentric collar 
> TB that US 
> Tower uses. They are really useless. 
> 
>     Hey - that was fun!
> 
> Cheers,
> Steve    K7LXC
> TOWER TECH 
> Steve    K7LXC
> 
> 
_______________________________________________

See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with
any questions and ask for Sherman, W2FLA.

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