In a message dated 5/2/2010 9:59:22 P.M. Pacific Daylight Time,
towertalk-request@contesting.com writes:
> If the cables don't need replacing at the rate "the field" is replacing
them, then why do we get any cable breaks?
Are there other issues?
See the email I just posted about cables breaking.
> Most hams don't do much maintanence, from the cables on used towers
I've
bought. So it's hard to understand an anecdotal story of "most cables
that are replaced don't need to be".
Well, as a UST factory authorized installer and installer of a dozen
or more crank-ups, I also do PM to them so I've seen lots of older crank-ups
and that's been my experience. Amateur use is very occasional as compared
to commercial service and isn't subjected to hard daily use.
> Worse is the problem with lack of bearing maintainence. I've seen
severely worn bronze bearings.
And corrosion/wear on the aluminum pulley wheels, sometimes leading to
very hard to turn.
This is true for older crank-ups but for years they've used pressed-in
sealed bearings which are much better. It's almost impossible to see the
pulleys move in most UST's, hence the move to a higher reliability pulley.
> If replacing cables at X interval isn't fixing the problem, what will?
I think any used tower needs it cables replaced and pulleys rehabbed.
Maybe.
> I've gotten a tower where the cables were replaced with apparently EHS
cable: very hard to cut, had to use angle grinder. Owner apparently
thought stronger was better, but it was stiffer and probably worse over
the narrow diameter pulleys.
I don't know what it was but it wasn't EHS. EHS is very difficult to
bend and wouldn't work in any other application except for straight pull guy
wires.
> I'm guessing, on the west coast, that 10 years might be the right
period
for cable/pulley teardown.
20 years seems too long. Maybe 5 is too short. Any time it changes
owners seems right too.
Time has nothing to do with it - it's cable condition. I recently posted
the 3 reasons why you'd want to replace the cables. They are damage, bad
rust and excessive broken strands. None of the crank-ups I've seen or worked
on met those criteria so they didn't need replacing.
> Where do the cables break? I've seen a photo of a break near the
compression sleeve, and I've read some inspections that detail the area
within 1 ft. of a compression sleeve as warranting extra inspection
because of possible increased stress/damage to the wires during the
compression sleeve install.
It's more due to external forces. See my related post.
Cheers,
Steve K7LXC
TOWER TECH
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