I won't bore the readers with the usual retread questions. Already did the
reading etc. and lowered the old beam a month ago. This is one on how to rig
the haul line to pull up the 110 lb SteppIr yagi.
The tram line is to be rigged about 3 feet above the top on the Rohn 45 tower
which has a flat top plate. The boom will be mounted right above the top
plate. The tram line is continuous in that it goes thru a pulley and down to a
'back stay point'. Trying to allow the tram line some ability to move but
direct most of the force down the mast to the rotor.
The beam will be hung from a sling that connects a pulley to the tram
line. The boom will hang about 18 inches below the tram line. A tiller/torque
arm will be attached 'behind' the boom, keeping the boom from rotating in two
The haul line is half inch polyester double braid and will be tied to the boom
close to the CG point. The bracket that holds the tram line above the tower
top has a place for a pulley to be mounted for the haul line, probably attached
with a snap link or shackle. The question I have is how to rig the haul line's
pulley such that I can pull straight down and not have interference with the
tower's top plate. The bracket for the pulley is about 3 inches out from the
mast and the tower needs about 9 inches clearance from the mast to go straight
down without rubbing on the edge of the top plate. I fear way too much
friction if I allow this. I lowered the prior beam this way and used the
friction to advantage but do not want such issues when pulling up the new beam.
If I rig the haul line pulley ( a CMI 2.375 inch 95% eff. rescue type) such
that it is hanging out far enough to clear the top plate, I end up pulling
sideways on the mast.
There must be a standard practice here but I have not yet read any postings
about this detail. I usually just 'go for it' and keep the fingers crossed. I
have way too many PhDs in the School of Hard Knocks and prefer to not get
If I can pull the beam up as far as it can get, to the haul line pulley, I plan
to relax the tram line and let it settle the boom down where it will rest on
the top plate until I can use other means to raise it the 6 inches to the boom
to mast plate.
Willing to call to talk about it.
Tnx in advance.
Yeah, I'm missing the CW test due to delay in getting this up.
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