[TowerTalk] crank-up tower safety

[Al Williams]

I have winch safety questions that I hope TowerTalkers can answer and will
find interesting.

I have just tilted my new Triex LM470 motorized tower (now called SKY470) to
the vertical
position (still nested).  It took all of my strength applied to the winch on
the tilt raising fixture to get it off the ground and much of my strength
until the tower was up 45 degrees or so.

The winch is Fulton K1550/KX1550 and has, in addition to the rachet pawl, a
feature that
allows the winch handle to unwind i.e. lower the load without using a rachet
pawl.  The maintenance instructions advise checking the friction disks that
are in play when unwinding and has caution that the load can slip if the
friction disks are worn or if the locking nuts are not positioned properly.

I recently helped in the tilt-over of a 70' motorized USTower.  The winching
effort required was  far less (easy) than the Triex.  The major reason for
the difference appears to be that
the USTower uses double pulleys at both the tower end and the raising
fixture end, whereas the Triex uses only a single pulley (for a 2:1
advantage) on the tower end.

I suspect that the winch on the Triex may be overloaded and also feel that
the pulley system should be modified.  It has been many years since my
physics courses.  Are my assumptions and calculations valid?

1. The ~1200 lb tower is resting on the pivot bolts at the bottom end and a
log at the
other end.  The tilt-raising cable is approximately 8' from the bottom end
and the other
end is 16' from the cable.  For simplification I assume 600 lb of the tower
at each end although I know the bottom end is heavier.  Is it correct that
the force required at the
cable (8' from bottom end) is 600x24/16=900 pounds?


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