TT:
I did the same thing for a top and middle plate clamp with my recent
Trylon installation, except I used muffler clamps. I cut off about 3/8 inch
of the tips of each clamp, cleaned them with degreaser, then sprayed with
cold galvanizing. I used two long carriage bolts instead of the u-bolt to
fasten two facing clamps onto the mast above the top bearing. I fastened a
second set a couple of inches above the middle plate; this way it's there
when I go to remove the rotator and I don't have to look for it.
N3RR and I also used the clamps temporarily to support the mast as it
was being hoisted by a come-along through the three plates. I rested a
clamp on the middle rotator plate and top bearing and tightened them before
Bill released tension on the come-along to reposition it. When he was
ready, I loosened both clamps and he pumped on the handle again.
73 de
Gene Smar AD3F
-----Original Message-----
From: Jerry Kincade <w5kp@swbell.net>
To: Chuck Lewis <clewis@knology.net>; W8JI@contesting.com
<W8JI@contesting.com>; towertalk@contesting.com <towertalk@contesting.com>
To: <towertalk@contesting.com>
Date: Monday, December 17, 2001 7:27 PM
Subject: Re: [TowerTalk] Hink and Kinks
>
>If one wants to relieve the vertical weight, back-to-back galvanized U-bolt
>saddles fastened with a couple of grade 5 bolts is a much easier (and maybe
>much safer) solution, and doesn't weaken the mast. All you need to do is
>grind off their tips to allow for pulling them tight without hitting each
>other. I used this setup on the upper thrust bearing. The lower bearing is
>left "loose" and will only be used for mast stabilizing for future rotator
>pulls. It worked like a charm with a pair of Rohn bearings. I wanted the
>weight off the rotator so I could easily pull it when needed without having
>to mess with the mast first.
>73, Jerry W5KP
>
>----- Original Message -----
>From: "Chuck Lewis" <clewis@knology.net>
>To: <W8JI@contesting.com>; <towertalk@contesting.com>
>Sent: Monday, December 17, 2001 1:19 PM
>Subject: Re: [TowerTalk] Hink and Kinks
>
>
>>
>> I had the same reaction when I read it, and also the same question
>regarding
>> editorial review of QST articles.
>> Furthermore, the previous hint, from the same submitter, has us drilling
a
>> hole in the mast just above the thrust bearing in order to transfer
>vertical
>> loads to the bearing so we don't have to rely on the jam-nutted bolts
>> normally used through the bearing upper collar. I can't think of a worse
>> place to weaken a mast: right at the point of maximum bending stress.
>Sure,
>> we've argued over drilling and pinning masts to rotator upper brackets,
>but
>> that's in a relatively safe spot. I can see it now...hundreds of ten-foot
>> lengths of two inch water pipe being drilled for a 3/8" bolt right at the
>> prime failure point.
>>
>> This brings up a pet peeve: Why are we so determined to remove the
>vertical
>> load from rotors unless it exceeds the makers specs? I'm an EE, not a
>stress
>> guy, so my credentials are questionable, but my intuition tells me that
>> rotors DEPEND on some vertical preload to obtain lateral (radial?) load
>> reaction from their bearing races, and to maximize bearing life. Sure,
>each
>> rotor design will treat this a little differently, but their specs will
>> account for it, and they all seem to be clear on the allowable vertical
>load
>> for the size of the rotor. My Rohn "thrust" bearing is set up with the
>> jam-nutted screws just clear of the O.D. of the mast, so the "thrust"
>> bearing is reacting against RADIAL thrust loads and reducing the
>overturning
>> load applied to the rotor (NOT the weight of the mast plus antenna). My
>> total "stack" weight is well within the allowable vertical load as
>specified
>> by the rotor manufacturer; and is constant, so there was no good reason
to
>> reduce it. On the other hand, wind-induced overturning moments could
>> conceivably exceed the capability of the rotor, and the "thrust" bearing
>is
>> there to add additional protection against excessive bending loads at the
>> rotor. The bending load becomes zero-ed out by the "thrust" bearing, and
>the
>> rotor races are subjected to lateral (radial) forces instead. Having a
>> vertical pre-load ensures that these races have a chance to do their job.
>> When I check things at the top, I make sure the bearing collar will
rotate
>> around the mast and that the jam-nutted screws are still just clear of
the
>> mast OD. AND...there are never any alignment problems.
>> Now...had I placed a BIG stack up there, with a vertical load which
>exceeded
>> the allowable for the chosen rotor, a thrust bearing that shared some of
>the
>> vertical load would have been appropriate. In that case, however. the
>> hint/kink we're bashing becomes even scarier!
>>
>> Chuck, N4NM
>>
>> ----- Original Message -----
>> From: "Tom Rauch" <w8ji@akorn.net>
>> To: <towertalk@contesting.com>
>> Sent: Monday, December 17, 2001 12:28 PM`
>> Subject: [TowerTalk] Hink and Kinks
>>
>>
>> >
>> > Re: Add Safety and Comfort Jan QST page 67
>> >
>> > This seems like a death wish!
>> >
>> > I can't imagine standing on a rubber hose that was slit and installed
>> > over a tower rung....even if it is RTVed in place!! All it needs to do
>> > is spin, and woops...there go your feet out from under you
>> >
>> > Does this concept bother anyone else, or am I paranoid about
>> > having a solid foothold?
>> > 73, Tom W8JI
>>
>>
>>
>>
>> List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
>> Trylon Titan towers, coax, hardline and more. Also check out our self
>> supporting towers up to 100 feet for under $1500!!
>http://www.anwireless.com
>>
>> -----
>> FAQ on WWW: http://www.contesting.com/FAQ/towertalk
>> Submissions: towertalk@contesting.com
>> Administrative requests: towertalk-REQUEST@contesting.com
>> Problems: owner-towertalk@contesting.com
>>
>>
>
>
>
>List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
>Trylon Titan towers, coax, hardline and more. Also check out our self
>supporting towers up to 100 feet for under $1500!!
http://www.anwireless.com
>
>-----
>FAQ on WWW: http://www.contesting.com/FAQ/towertalk
>Submissions: towertalk@contesting.com
>Administrative requests: towertalk-REQUEST@contesting.com
>Problems: owner-towertalk@contesting.com
>
List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 100 feet for under $1500!! http://www.anwireless.com
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
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