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[TowerTalk] crankup tower

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Subject: [TowerTalk] crankup tower
From: (Charles H. Harpole)
Date: Mon, 9 Jun 1997 21:27:07 -0400 (EDT)
Two important factors in crank-down towers during wind.  One is that the
tower must be rigged for POSITIVE PULL DOWN (as well as "pull up").
Otherwise, that is, unless the winch is actually PULLING the tower down,
the sidewise wind pressure will keep the tower from coming down.  And, if
operator persists to try to crank down, the upper sections will simply
hang there, the cables will get loose, and when the wind lets up for a
moment, the upper sections will come zooming down, likely overloading and
snapping the cables--disaster!  
Second, my experience with crank towers is that you will want to BE
PRESENT during any kind of cranking, down or up, despite automatic
devices.  Failure of any auto device, or the blowing of a dipole wire into
the works, or whatever, means a really nasty event.  
I had a winch to fail (main shaft snapped) and dropped the HD-70 with
fully loaded antennas.  Gives a real stress test to beams, and in the
wrong direction!  73, K4VUD

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