[TowerTalk] Tram Pulley
K8RI-on-TowerTalk at tm.net
Wed Sep 24 01:18:00 EDT 2008
OK Guys, lets not get carried away. If some one needs the "good stuff"
then fine, I'd use it too. If you are lifting heavy antennas and your
tram line is going to stay out in the weather for years, then a SS
pulley/Marine hardware is great. It's also great for a SS tram (two
pulleys on bearings in a fitting). These fittings also have close
tolerances so you can use a smaller cable or rope, but why purchase a
large pulley for a small cable or rope? However, for the week or week
end to put up a 60, or even 100# tribander, or even 140 - 150# antenna
they just aren't necessary. Even for halyards to pull up wire antennas
using 3/16" - 5?16" poly rope they aren't necessary either. OTOH he
didn't say how much the antennas weigh only that they are "medium size".
5/16" "braided" poly rope, or 1/4" Phyllistran the less expensive
hardware pulleys work just fine (IF they have the proper rating) to
handle what you are lifting. With 1700# rated rope, or Phyllistran of
4000# test or greater That 1/2" (4" diameter) hardware pulley rated at
750# is more than enough for the antennas I have. I'd hasten to add that
although I'm back to climbing at my age, I'm limiting the maximum
antenna weight to the neighborhood of 100#.
For my halyards I use simple, inexpensive 90# rated *cheap* pulleys and
have never had one rust, corrode, or fail yet and if they did fail it'd
be no big deal.
If I were 30 years younger, still working and not on a pension plus SS,
and in the middle of the "Dot Com Boom", I'd have the very best up there
as well. Of course if the above criteria were met, I'd also have a
larger house, much more land, and multiple towers with mono-banders, but
I'd probably be too busy out flying airplanes to get on the air (except
airborne mobile) ... Been there and done that<:-))
Talked to my wife in her car just leaving the driveway and I was using
my HT running 5W at 22,000 feet over South central Ohio. She was
pulling into MBS's parking lot (Located in central lower Michigan) just
as we were touching down about 45 minutes later. Of course if I'm going
to dream it'd be 30 years younger, already retired and a healthy income
on the side. <:-))
HOWEVER I would caution any one to make sure every thing they use has
the proper ratings (with a healthy safety margin) and is treated
appropriately to its construction/materials. Remember that 750# rated
steel hardware pulley isn't going to hold near that much after it's been
left out in the weather for a year or two. Actually it probably wouldn't
after a month, particularly if the pulley is plastic out in the sunlight.
Remember too that a 100# antenna hanging on a 3 or 4" diameter pulley
can exert a lot more than 100# force on the cable or rope supporting the
pulley. Also that rope or cable is going to be under at least several
hundred pounds of tension in addition to the weight it supports.
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