[TowerTalk] Rope breaking strength vs working strength ???

[Don Moman]

I won't get into the safe vs breaking strengths, but to answer your main
question - I would use the 1/2 inch poly, or even slightly less, with
confidence. But I would prefer to use 3/16 or 1/4 wire rope, mainly from
an abrasion factor, plus the lack of stretch (comparatively) makes
tensioning easier. The tightness of the tram rope when you attempt to take
the sag out with the beam in the midpoint, is what will break the rope.
Saying that, there is no need to have the rope very tight at all, except
when the beam nears the tower - and by then the wight of the beam is much
nearer the end so the tension in the rope can be much less.

If the mast is skimpy, back guying is cheap safety factor if you have the
room. For heavier beams, I much prefer to tram up to just above the last
guy point on the tower, then transfer the beam to a chain fall type of
lift for the last few feet. Very safe and complete control of lift for
that crucual positioning. 

Good luck with the project Sam!

73 Don
VE6JY


On Mon, 21 Aug 2000, Sam Ferris wrote:

> 
> Towertalkers:  In the midst of building a short stack on 20 (3 over 3
> over 3 - all on 24 ft booms) and now that we are to the stage of
> tramming antennas up the tower, the question of strength of the tram
> line has arisen.  Refering to several internet listings and the March 92


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