There is little doubt that crank up towers in the 70-90 foot class require
some special maintenance considerations. They are pushing the mechanical
design envelope by their shear weight and potential stresses. However crank
up towers in the 40-50 foot class have been well documented over the years
and will provide years of trouble free performance.
I personally have a Tri-Ex W-51 fifty foot tower that I have used for 30+
years. The tower is generally fully extended and only retracted a couple
times a year. Of course, I do a routine annual inspection each spring and
thus far have found no need to replace the original cabling. As always,
YMMV.
73 Bob W7KD
----- Original Message -----
From: "Dan Bookwalter" <n8dcj@yahoo.com>
To: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>; <towertalk@contesting.com>
Sent: Thursday, December 29, 2005 10:21 AM
Subject: Re: [TowerTalk] Question for crank owners
Rob
on the tx-472 and probably most or all US Towers the
cable is the only thing standing between a nice
looking tower/antenna system and a pile of scrap
metal...
Dan
--- "Rob Atkinson, K5UJ" <k5uj@hotmail.com> wrote:
>
> hi everyone,
>
> thaks for all the email about my crank-up
> questions--i rx so many i may not
> have time to answer each one individually but tnx vy
> much all the same.
>
> part of my reason for asking is that i might
> eventually install a small 40'
> crank up and wanted some information on how these
> things work in order to
> make a decision. It sounds as if when the tower is
> fully or partly
> extended, the cable continues to hold the weight of
> all the sections. Is
> this true? Or is the cable only supporting the
> sections when raising and
> lowering the tower, and other times there is some
> sort of locking mechanism
> that can be released into place? If so, that
> would be okay, otherwise,
> there's something about the idea of a cable and
> pully system holding all
> that weight all the time that bothers me, although i
> admit that in my case
> it would be only one 20 ft. section so may not be a
> big deal.
>
> I recall that at one time, some company made crank
> up towers in which the
> top 2/3 of the tower pivoted on a hinge--a lattice
> lever extended down one
> side below the hinge with a cable on the bottom of
> it, which went directly
> to a winch at the bottom of the fixed 1/3 of the
> tower below the hinge.
> the whole top 2/3 folded over, then you'd reel it
> back up on the hinge and
> lock the bottom of the lever to the bottom fixed
> part of the tower, thereby
> having structurally, almost the strength of a
> permanent tower. Are these
> towers being made? I think i might be able to
> make something similar by
> putting a 40' lattice tower on a base hinge, with a
> cable at its midpoint,
> then run the cable over to a fixed pully up about
> 20' and a few feet away on
> a parallel short tower and down to a crank at the
> bottom and raise and lower
> the whole thing this way, locking the free leg at
> the bottom with a bolt.
> just another idea to consider.
>
> 73
>
> rob / k5uj
>
>
_________________________________________________________________
> FREE pop-up blocking with the new MSN Toolbar - get
> it now!
>
http://toolbar.msn.click-url.com/go/onm00200415ave/direct/01/
>
> > _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting
> Towers", "Wireless Weather Stations", and lot's
> more. Call Toll Free, 1-800-333-9041 with any
> questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
>
http://lists.contesting.com/mailman/listinfo/towertalk
>
__________________________________
Yahoo! for Good - Make a difference this year.
http://brand.yahoo.com/cybergivingweek2005/
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|