Hmmm. This is a little hard to visualize. If I slip a pipe into the top of
the bottom section and lower the tower to allow the first movable section to
come to rest on the pipe, I can see that the wire rope will become slack.
But then, what's holding up the higher sections?
On my 71' U.S. Tower tubular (which can't be pinned this way), there are
three sets of cables for four sections. The main cable is wound on the
winch. One end goes under the first movable section above the bottom section
and is used to raise that section. The other end is attached to the top
section and serves as the positive pull-down cable. Each of the middle two
sections has a separate cable attached to the section above it and to a
pulley system at the top of the section below it. When the main cable lifts
the first movable section, this configuration automatically raises the top
two sections. Those two other cables would remain taut, even if tension was
removed from the main cable. Is a similar arrangemnt used on the triangular
towers?
73, Dick, WC1M
-----Original Message-----
From: David L. Thompson <thompson@mindspring.com>
To: towertalk@contesting.com <towertalk@contesting.com>
To: <towertalk@contesting.com>
Date: Thursday, June 11, 1998 11:08 AM
Subject: [TowerTalk] Guying crank up towers
>
>Much has been said about not guying crank up towers. I can't speak for the
>other brands of towers (some of which are gone or are going) but my Tristao
>can be guyed. It is designed as a totally self supporting tower, but at
the
>time Tristao made a series of guyed crank ups (TRi-Ex did too) and the
>design of the rope/pully system for my tower (same design was in the
>Towermaster and now US Tower design) allowed you to pin the bottom section
>with a steel pipe (actually crank the tower down slightly so the bar
>supports the tower not the pully ropes.) The pully sections are dependent
>on each other so the tension on the rope becomes slack (not loose).
>Slipping 2 or 3 inches would tighten them back up.
>
>Lou Tristao gave talks at hamfests and Dayton on this subject but my copy
of
>his talk has long since disappeared. I did have Lou put guy rings on my
>tower and I have used the Rohn guying sets ever since altho I plan to go to
>4000Lb Phillystran soon for the top two guys (6 total).
>
>Look at your tower (If not one of those listed above) and better yet ask
the
>question of the manufacturer. I do know several who guyed the Rohn crank
>ups. The secret of long life to quote Lou is "Take the weight off the rope
>and pully system once the tower is fully extended whether guyed or free
>standing." I will throw in that guys don't hold up a tower. They "steady"
>the tower from falling a certain direction in the force of wind. Don't put
>too much tension in the guys!
>
>Dave K4JRB
>
>
>
>--
>FAQ on WWW: http://www.contesting.com/towertalkfaq.html
>Submissions: towertalk@contesting.com
>Administrative requests: towertalk-REQUEST@contesting.com
>Problems: owner-towertalk@contesting.com
>Search: http://www.contesting.com/km9p/search.htm
>
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|