[TowerTalk] Torque Arms

Michael Tope W4EF@pacbell.net
Wed, 21 Apr 1999 18:58:38 -0700


Can anyone tell me what the length is for the Rohn TB25 torque bars that go with the 
GA25GD guy bracket? They are not shown in the catalog and I am wondering if they 
create a larger or smaller cross section than the TA25 torque arm stabilizer assembly. 

I am trying to rebuild a large HF stack (300 lbs/20 sqft) and am concerned about 
rotational inertia and wind induced torque being transmitted from the antennas thru
the rotator and into the tower. I have seen some broken welds on the current installation,
but this appears to be due to a faulty rotator installation (the rotator was attached to the
rungs instead of the tower legs as a quick "get on for the contest" kludge and was never 
fixed). Is it better to let the tower twist with the load, or stiffen the tower with the torque 
bars? And if I install the torque bars, how close should the rotator mounting point be to one 
of the torque bar augmented guy points?

BTW, this brings up another question, do Rohn specs quantify allowed torque loads on
25/45/55G anywhere in a manner similar to overturning moment? In other words, I know 
how to design Rohn tower for side load, but I do I quantify design margin for torque?

Thanks,

Mike, W4EF..........................


--
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