[TowerTalk] Ginpole for 20 foot sections

[Kurt Andress]

n4kg@juno.com wrote:
> 
> 
> A gin pole for heavy loads can be configured by using
> a block and tackle BETWEEN the SUPPORT and the LOAD
> where there are MULTIPLE pulleys and one end of the rope
> is connected to one of the blocks.
> 
 
Hi Tom and all,

Remember, when evaluating the true effect of the "reduced load" on the
ginpole, that if the load is not directly below the pole, but creates a
small angle between the line and the pole, that the pole is not going to
realize any significant reduction in stress from the use of the mechanical
advantage.

Put a 10 degree angle between the pole and the load line, look at the
bending stress at the base of the pole, and it will become apparent. A 12'
Rohn ginpole lifting 250 lbs realizes a 1.3% reduction in stress when the
mechanical advantage (between load and pole) is changed from 1:1 to 4:1. 

The mechanical advantage should be viewed as an aid to those lifting the
load, but not much help for the pole.

-- 
73, Kurt, K7NV

List Sponsor: Are you thinking about installing a tower this summer? Call us
for information on our fabulous Trylon Titan self-supporting towers - up to
96-feet for less than $2000! at 888-833-3104 <A HREF="http://www.ChampionRadio.com">
www.ChampionRadio.com</A>

-----
FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com