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Subject:
Re: [TowerTalk] Emergency Rohn 45 foldover help needed!
From:
"David Hachadorian" <K6LL@adelphia.net>
Date:
Thu, 10 Jun 2004 15:05:57 -0700
To:
"Towertalk Reflector" <towertalk@contesting.com>
----- Original Message -----
From: "Anthony Kapolka" <kapolka@wilkes.edu>
To: <towertalk@contesting.com>
Sent: Thursday, June 10, 2004 10:50 AM
Subject: [TowerTalk] Emergency Rohn 45 foldover help needed!
Hi,
I have a Rohn 45 foldover I was hoping to erect this saturday - I
have
a bunch of people coming over to help. Unfortunately, as I walked
through the pieces today, I found a large problem - the fold over
assembly does not match the engineering diagram I have! My diagram
is
from 1981.
I must have an older model.
The arm terminates in a bracket which has two holes:
------------------------------------
| |
----------------------------| |
| |
| O |
| |
| O |
|____|
presumably one is for a bolt/thimble to attach to the winch and one
is
to attach, somehow, to the tower leg.
I think you have the old-style boom assembly, like my 1978 version
Rohn 25 foldover.
The thimble goes in the hole near the end. When the tower is almost
upright, you can move it by hand, leaving some slack in the winch
cable. The thimble will slip past the tower leg, then you jam a bolt
or clevis pin through the second hole, behind the tower leg, so the
tower cannot fold over and all tension is removed from the winch
cable. I think it is a 3/4 bolt or clevis pin. You can put a nut on
the end of the bolt to keep it from slipping out (although I never did
put one on mine!). If you use a clevis pin, put a cotter pin through
the end.
The other big question is whether I should assemble this tower with:
27' below the hinge and 36' above (which is about what Rohn
suggests) or
37' below the hinge and 27' above (which sounds safer to me - but i
have a guy here vigorously arguing I need to follow Rohn's model)
I am guying this at the hinge and at the top.
Do it the way Rohn recommends. There is a LOT of asymmetrical tension
on the guys wires when the tower is folded over, and 37' (actually
39') between the ground and the first set of guys under those
conditions is probably too much. If it were ok, Rohn would have
marketed a 74' or 84' version of this tower. The non-approved way
would also leave your antennas 14' above ground, upside down, and
interfering with the lower guy wires when it was in the folded
position.
Also, with the old-style boom assembly, on the 64' tower, I think the
Rohn literature showed a pulley, about 10' above ground, just below
the point where the bottom of the boom comes down to the tower. The
lifting cable goes through that pulley and then runs vertically the
last ten feet down to the winch. I've lost my old literature on this
tower, and am going from memory on this part. Maybe someone with a
Rohn catalog from the 70's can verify that. If you have a spare pulley
in the tower parts kit, that's what it is for.
Dave Hachadorian, K6LL
Yuma, AZ