[TowerTalk] LM 470 towers

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I have had three different LM-470 towers over the years and each has a  
balance overlap or extension when completely retracted.  It is true that  when 
all the way down it is not possible to service or install a rotor, the  
solution was to not lower it all the way.  This meant working a little  higher 
up, but not very much.   
 
am surprised that there has been an adjustment of the lifting cables that  
allows the last two sections to be more extended when the tower is  lowered. 
 The cabling system uses a pair of  cables connecting the  bottom of a 
section with its preceding mating section. Only the bottom moveable  section is 
lifted directly on the cable tied to the winch.  Other sections  are slaved 
to each other, coupled as I previously described.   Given  this arrangement 
then, for two top sections to not be fully nested suggests the  lifting 
cables have been shortened at least twice (cables must go up over a  pulley and 
then back down) the distance of the deviation from the full nested  
position.  
 
More important is the fact if these top cables are shorter, then the  total 
travel of the other sections has to match that length as well.    This 
means the other two moveable sections can not travel more then the top two,  and 
since they are already extended in the "nested" position they have less to  
travel to be fully extended, which limits how far the lower two sections 
can  travel.  
 
This means that some form of travel limit has to be set for the lower  
moving section, and that will be less then its full travel capability (has to  
equal the travel of the top section).  So if the top cables are shorter,  
then the fully extended height will be reduced because the bottom sections  
travel is limited.  
 
I would find this an undesirable arrangement - I would also check to see if 
 a section is hanging up and not dropping all the way.  A clue is that one  
of the cable sets will be come very slack -  be careful as what ever is  
restricting the motion could suddenly release allowing the sections to  drop.
 
Norm W4QN
 
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Date: Fri, 08 May 2009 21:02:26 -0700
From: "Bob Selbrede, K6ZZ"  <k6zz at ccis.com>
Subject: [TowerTalk] LM-470 Cable  Question

Folks,

When fully nested, the top two sections of my  LM-470 are
extended about 30" each verses the roughly 8" to 10" I  would
expect.  The third section from the top (second from  bottom)
nests properly.  In other words, when the lowest  moving
section reaches the lower limit, the top two sections are
extended  more than they should be.  I suspect the cable
system isn't adjusted  correctly.  The LM-470 documentation
is very lacking when it comes to  explaining how to properly
install and adjust the cable system.  Does  anyone have a
better set of instructions on how to replace and adjust  the
cable system?  Is this an adjustment issue or are the cables
on  the upper two sections too short?

73, Bob  K6ZZ
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Message: 3
Date: Fri, 8 May  2009 21:18:44 -0700
From: "Mike" _noddy1211 at sbcglobal.net_ (mailto:noddy1211 at sbcglobal.net) 
Bob,

I  asked this question of Karl at Tashjian Towers when I was there a few
weeks  ago.  He told me that this is the way that it is designed to  allow
people to install Rotators when in the crank down position, otherwise  when
fully cranked down it was too difficult to find a spot to get a Rotator  in
between the V braces when the tower is vertical.  

The cables  that control those two sections cannot be adjusted, se if it
really worries  you, you would have to get a couple of cables made 18 inches
or so  shorter.

I agree with you thinking that the two top sections should stop  on the
welded stops, but as I say that is not the way it is designed now. I  am
guessing this was a kind of work around after complaints.

Mike,  K6BR




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