[TowerTalk] Tower Guy Calculations

[Shawn Donley]

There are a few crank-up towers that were designed to be optionally guyed.  The one I'm familiar with is the old EZ-Way crank-ups that have beefy brake plates which flip in to hold the section above and thus take the loads off of the lift cables.  A quick web search for old EZ-Way Tower brochures will show some info.   I have an EZ-Way RBZ-75 which is guyed at the top of the first and the second sections.  Once I have the sections locked, I take most, but not all, of the tension off the winch cable.  The lower guys are preloaded (Loos gauge) at the normal 400 lbs for 3/16 EHS but I keep the set for the second section a little backed off, to about 250 lbs.

That said, the complex load paths through the brake plates onto the rungs at the next lower section would certainly make a FEM analysis of this setup quite difficult. 

After many years, I have not had any problems with this setup carrying an Optibeam OB9-5 and a dual band VHF/UHF vertical.  But I'm also surrounded by tall trees that significantly diminish the wind loads.  My biggest risk is one of those big trees falling on a guy line and pulling everything over.

If the crank-up does not have design features to lock the sections and the manufacturer's  instructions do not specifically say it can be guyed, then don't guy it.  The loads into the lift cable will be too much for it.  Final note ... even with these section locking features, I do not consider the tower safe to climb.  When it's maintenance time, the top and middle sections get lowered and a man-lift used.