[TowerTalk] multi-sheave pulley

[K9MA]

What I've done when lifting 100+ pound antennas is to run the lifting 
rope down to a pulley low on the tower, then back up to the top.  I then 
wrap two slings of smaller rope around the lifting rope with Prusik 
knots. One sling goes to the come along, which pulls UP on that section 
of rope to lift the antenna. The come along goes where I can reach it 
when working on the antenna. The other sling goes above the first one, 
attached to the tower with a carabiner, both as a safety and to secure 
the rope when it's time to let out the cable on the come along.

Note that the lower pulley sees twice the load on the lifting rope, so 
make sure it's secure.

I've used this scheme many times when assembling antennas on the tower. 
(Which I have to do due to space limitations.)

73,
Scott K9MA

On 11/14/2019 08:30, Jim Thomson wrote:
> Date: Wed, 13 Nov 2019 12:26:10 -0500
> From: Dave Sublette <k4to.dave at gmail.com>
> To: kj6y--- via TowerTalk <towertalk at contesting.com>
> Subject: [TowerTalk] multi-sheave pulley
>
>
> <The trouble is, at age 77 I no longer have the arm strength that I once
> <had.  So,  I would like to use a multi-sheave system to reduce the force
> <necessary to lift it off and reinstall it.  I have a two pully system which
> <would reduce it to half, but I think I had better go with a three or four
> <section system.
>
> <All this to ask what is a good three or four sheave fully?  It only need be
> <a two inch diameter. Or, a one inch would work also.  If you have any
> <knowledge which one and where to get it, it would be appreciated.  In the
> <meantime, I will do my own searching.  But, I thought it would be good to
> <have the input of someone who has actually used what they recommend.
>
> <As always, I look forward to the excellent advice that comes from this
> <group.
>
> <73,
>
> <Dave, K4TO
>
> ### Use a ....cumalong.    Easy, and  much better  control  vs a lawn  tractor.
>
> http://ds-studio.co/cumalong-tool/    The  1st  pix, is  the  version  I have. It  has
> the  2nd  hook  option.....  so you   double  up  on  the  cable....so  its  only  half
> as  long,  but  capacity  increases  from 1 ton  to  2  tons.  You then  also get
> an  even  finer adjustment  for  a given  amount  of lever  pull.   An 88  lb  rotor
> would  be a piece of  cake.
>
> ##  I  use  a  multi  sheave /  rope  setup  to  get a yagi  to top  of  tower,  then  the  same
> cumalong  to do the  last few  inches.    Grnd  crew lifts  yagi  up to  top  of  tower,  then  I
> hook the  cumalong  to a 2nd quick  rls  shackle.   Grnd  crew  then  goes  home.   I  lift  yagi
> the  last little  bit....  then....using  my  hb  version  of  the  infamous  F12..easy  on  mounting
> scheme,   mate  the  horz boom  plate  to the already installed vert mast  plate.
>
> Jim  VE7RF
> _______________________________________________
>
>
>
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-- 
Scott  K9MA

k9ma at sdellington.us