[TowerTalk] positive pull down for Tri-ex towers

[Craig Clark]

At 16:54 7/10/2008, you wrote:
>Most towers that were designed not to have positive pull down cannot 
>be EASILY modified to have the pull down feature.  It all comes down 
>to the fact that the pull up cable has to wind in at the same rate 
>that the pull down cable is letting out and vica-versa.

Bob,

Not completely true. The "however" is you have a manual positive pull 
down system.

I agree that you cannot retrofit the same system as on the larger 
towers that are designed with a positive system.

Here's what I did. I attached an 7x32 aircraft cable to the bottom of 
the top section. I chained a pulley to the bottom of the tower and 
ran the cable thru the pulley. I used a cable compression clamp to 
grab the aircraft cable and attached that to a come-a-long. Normally 
I'd use my tractor as an anchor point but I also used my truck.

I'd first tension the top section with the come-a-long. I would then 
lower and tension, lower and tension. I watched to see if the top 
tower wire would go slack and if it did, I'd raise the tower, 
re-tension and then lower again. Normally, after lowering the tower 
1-2' gravity would take over and there was no more need to use the 
"positive" system.

The reality is that my W-67 would not come down without the system I 
designed. I had a friend at the local fire dept come over and I did 
all this work while hooked in to a fire ladder. I would never climb a 
crank-up even if it was blocked with 4x4's. Not never ever.




73, Craig Clark, K1QX


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