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[Towertalk] crank up "fit"

To: <towertalk@contesting.com>
Subject: [Towertalk] crank up "fit"
From: dhearn@ix.netcom.com (dan hearn)
Date: Sun, 15 Dec 2002 16:03:04 -0800
The 2 UST crankups I have are not tapered and the looseness between
sections is needed so they don't jam up, particularly when you try to
lower it and a side wind is present. My 472 does not have a winch and
power pulldown. I use a floor block and my tractor to lift and lower it.
The last thing you want is a tight fitting crankup tower.
  The sections are supported by the cables. My 131 ft UST has 3 cables
at each section. This gives triple redundency and centers the tower
lifting. My TX472 uses single lift cables between sections and there is
a slight tendency for the sections to tilt a tiny bit during lift since
the cables are pulling on only one side of the section. It was used when
I got it and once it stuck on the way down since the section weight is
what makes it come down. When I finally got it down, I did a little
hammer work on the guide angles to loosen the fit. I also attached a
cable to the bottom of the top section which hangs down the center in
case it sticks. It has not happened in the last 10 years. Both towers
use a single lift cable on the bottom section with multiple passes, back
and forth, for mechanical advantage. 
  I use a 2 section ladder against the bottom secton to work on the
tower and antennas. I recently replaced the cables on the 472 and the
bearings in the pulleys by blocking the sections being worked on and
working from the ladder.

rpb wrote:
> 
> I'll ask this again since I really didnt get much of response before, and it 
> was buried in another lengthy post...
> Just bought a crank up, never thought i would but couldnt pass the deal up...
> 
> Im not sure how to posit this question...  On any of these crank-ups I 
> realize one can stop it anywhere in between fully extended and retracted, but 
> does the tower "lock-up" tighter when fully extended vs. wobble when ony 
> partially so ?  Or is the mechanical "fit" the same at all points on the way 
> up?
> 
> I realize that the entire load is held by the wire rope in any case, but what 
> about the "mechanical lockup" for lack of a better term.... does the tower 
> "lock up" better when at its full extension any better worse than at some 
> other partial setting ?  Is the "fit" of the sections tapered or identical at 
> all settings?  Im trying to describe the lateral inter-section mechanical 
> "fit"....
> 
> is the inter-section "wobble" a constant, or does it tighten up at full 
> extension?
> 
> tough to describe what i am thinking.....  all the same query, different 
> words....
> 
> what if i put my head inside one of the lower sections while cranking it up 
> to check the bottom of the rotor plate out ?
> 
> -bob
> 
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