In a message dated 12/9/02 2:10:43 PM Pacific Standard Time, w9zv@attbi.com
writes:
> I just purchased a used UST HDX572MDPL. The tower was used for commecial
> purposes to test small S-band type antennas. Raising fixture, Yaesu 2800
> and Az/El 5400 rotators, thrust bearing, rotor plate, chrome mast, base,
> cable hangers/arms(??), etc... the whole kit and kaboodle, heck of a deal
> that i couldnt pass up...
>
> The paperwork suggests that it was new in 1996, and it has been down
inside
> a barn on skids for the last 4 years so it is virtually new and the duty it
> had been exposed to before was very light. Further, from the engineer who
> worked on it, he said that most if the time it was up it sat in a lowered
> state. Your typical "only driven on sunday to church" deal.... cool...
>
> However, there is some visible rust on the surface of some portions of the
> cables. I have not tried closely inspecting (bending it open etc) the
cable/
> wire to see if the rust simply is surface or worse...... otherwise it is in
> excellent condition even though crank-ups are not my preference for a tower.
Congrats on a good deal. Now for the fun part - hi!
As far as cable rust goes, it would have to be *real* penetrated rust and
not just surface rust in order for this to be a problem. Since it's
relatively new and been stored inside for several years, I doubt you have a
rust problem.
You should use a cable lubricant such as PreLube 6 in order to restore
the cable flexibility and prevent further rusting. <A
HREF="http://www.championradio.com";>www.championradio.com</A> carries it.
>
> In thinking about what needs to be done other than the obvious of diggin'
a
> big hole... I thought it may be good practice and prudent to replace all
> the wire rope/cables ( and any sheaves if necessary) before putting the
thing
> up. This is my first crank-up. Although i have volunteered to climb/work
on
> a number of towers and other crank-ups before, I have no idea how to go
about
> replacing the cables. I am going to be contacting UST this week to
inquire,
> but I wondered if there was someone out there with some experience in this
> regard...
First of all, UST won't tell you anything about how to do it. Tower
manufacturers are insurance-driven enterprises and they won't do anything
that may increase their risk and liability exposure.
>
> In particular :
>
> What are the techniques/procedures for doing this ? Anyone have written
> procedures they could send me ??
DO NOT TRY THIS AT HOME. The crank-up/positive pull-down systems are
relatively complex and require a working knowledge of the procedures and
techniques used in factory assembly. At the factory the towers are laid
horizontally and the guys use comealongs and a definite process and order to
assemble them. I spent a couple of days at the factory to learn how to do
this and I realized that I (or anyone for that matter) wouldn't be able to
replace cables in the field. There are only a couple of guys in the country
(one works for UST and the other is Skip, KJ6Y) that I know of who could
actually do this. It's a complicated job and one that I won't do.
> Any experience based recommendations/hints kinks that you have and could
> share??
> Any useful modifications to the "stock" procedures that can make this job
> easier ?
There aren't any.
>
> What kind of response can I expect from UST ?? Anyone have past
experiences
> with them directly in this regard ? Any particular approach with them more
> fruitful than others ? Or has the unfortunate successes of the "dump the
hot
> coffee in the crotch" litigation squelched UST's desire to speak to me ??
>
See remarks above about liability exposure. There are no drawings or
anything that they would share even if they existed (they don't).
> Are there other options ?? different grades/types of wire rope etc, that
may
> improve the breed from "stock" ?
The basic question is "Do you need to replace the cables?" The answer is
no. There are three conditions that would cause you to consider it.
1) Deep rust. This is potentially fatal but the cables would have to be in
extremely poor shape in order to have enough rust to warrant it.
2) Damage to cables. This is mostly kinks or flattened cable. I doubt you've
got anything like this.
3) Broken strands. Industry rule-of-thumb allows you to have 6 broken
strands before you need to consider replacement. I don't think you've got any
of this either.
Bottom line? Put it up and use it and don't worry about it.
UST has a company line that you need to replace the cables every 3 years.
This is a weasel clause; that is, if something happens and you didn't replace
the cables per their instructions, they can weasel out of any responsibility.
I've seen crank-ups 20 years old that still have the original cables. They
didn't meet any of the above 3 criteria so there wasn't a compelling reason
to replace them. What I did was PM them with PreLube and advise the owner(s)
to do this twice a year. They're fine.
>
> Are there other things to do on it that may also be prudent prior to
> erection (like changing the cable on the raising fixture)?
Probably not.
>
> Im not sure how to posit this question... On any of these crank-ups, do
> they have only two positions down and fully up ?? I realize I can stop it
> anywhere in between, but does the tower "lock-up" tighter when fully
extended
> vs. wobble when ony partially so ? Or is the "fit" the same all the way up?
>
The lower the tower, the more capacity it has. The raising and positive
pulldown cables are under constant tension so it doesn't make any difference
what height the tower is. The fit is the same everywhere. It doesn't "lock
up" anywhere - everything is always floating and held by the cables.
> Should I replace the limit switches ? One of them is fairly hard to turn,
> but this may simply be because of storage and would loosen up with a bit of
> wd-40 or equiv....
>
Turn? I think you mean switch.
As long as it functions, it's FB. If you want to replace them, knock
yourself out.
Here's what you SHOULD do with your tower:
1) Exercise it once a month or so. Raise it up and down to exercise the
cables.
2) Use a cable lubricant twice a year. The bearings are sealed so you don't
have to do anything with them.
3) Use different heights for tower operation. Don't always use the upper and
lower limits. The cables are more apt to take a set (a permanent deformation)
if they're always stressed at the same places (i.e. over a pulley).
You can get a set of drawings from the factory and you can use that for
base construction.
Cheers,
Steve K7LXC
TOWER TECH -
Professional tower services for commercial and amateur
US Tower factory authorized installer
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