I see my last message needs a bit more explanation:
We thought we were going to save some time by taking the rotor
and mast out of the top section after the tower was lowered down
enough to reach them. This meant the top section was not fully down
and I guess the center of gravity of the tower was further out.
The raising fixture has two heavy arms that bolt to the tower
base ears. (For a lack of a better term I'll call them ears.) These ears
are vertical pieces of metal that are welded to the base. Holes
are drilled in them to attach the raising fixture arms. These ears
will fail in that they just can't hold the tower with the top section
extended out and a large rotor & heavy mast in the top section.
Don't try it. The system works well as it's designed to just raise
a tower that is fully collapsed inside each section.
Don't try to insert a rotor & mast while the tower is still in a
somewhat horizontal plane. I had US Tower make up two metal clamps
that attach to the mast (one at each end) and are tightened down to
the mast by a bolt. I use the top clamp for taking the mast out of the
tower using a boom truck. The bottom clamp is in place just above the
rotor and is used to raise the mast by a hand cranked winch bolted
to the top of the tower, then the rotor is removed.
Hope this is clear. I feel use of a boom truck is a safer way to go
for antenna & mast work (for crankups).