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@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
------------------------------
Message: 3
Date: Fri, 8 May 2009 21:18:44 -0700
From: "Mike" _noddy1211@sbcglobal.net_ (mailto:noddy1211@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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