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Re: [TowerTalk] Photos of a Crank Up Positive Pull Down mechanism?

To: frohro@wwc.edu, towertalk <towertalk@contesting.com>
Subject: Re: [TowerTalk] Photos of a Crank Up Positive Pull Down mechanism?
From: "FISCHER,GREG" <ab7r@cablespeed.com>
Date: Thu, 05 Apr 2007 10:51:59 -0500
List-post: <mailto:towertalk@contesting.com>
I've also wondered about the positive pull down.  I have 
an old Hygain manual for their electric winch (I don't 
have the electric winch though) and it shows how to run 
the positive pull down cable.

If I recall correctly, the cable runs from the bottom of 
the 3rd section down to a pully at the bottom of the 
second section up to the top of the second section.  This 
is repeated with another cable from the bottom of the 4th 
section to a pulley at the bottom of the 3rd section and 
up to the top of the 3rd section.

How does this create "positive pulldown" when it is still 
gravity that brings the sections down when lowering with 
the winch?  Is it the weight of that 2nd section that is 
being used to help pull down the lighter 3rd and 4th 
sections?

Tnx
73
Greg
AB7R

  


On Thu, 05 Apr 2007 07:45:18 -0700
  Rob Frohne <frohro@wwc.edu> wrote:
> Hi,
> 
> I have two Tri-EX THD series towers and have had trouble 
>with them
> jamming when partially erected.  I am thinking of 
>putting a cable from
> the top section to a pulley on the bottom section so 
>that I could pull
> down if necessary if it gets jammed again.  I have read 
>of a thing
> called a "positive pull down" on some crank up towers, 
>and would like to
> see some photos of it before I do my thing, in case I'm 
>missing
> something, and they have a better way of doing it than I 
>am envisioning.
> Does anyone have any photos of a "positive pull down" 
>mechanism?
> 
> Thanks & 73,
> 
> Rob, KL7NA
> -- 
> Rob Frohne, Ph.D., P.E.
> E.F. Cross School of Engineering
> Walla Walla College
> 100 SW 4th Street
> College Place, WA 99324
> (509) 527-2075
> http://www.wwc.edu/~frohro/
> 
> _______________________________________________
> 
> 
> 
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