> No crank up I have seen meets either spec, so cable strength and life is
> degraded accordingly. If the tower engineers designed for this loss in
> strength, then all is ok. Crosby has more data:
>
> https://www.thecrosbygroup.com/html/en-US/pdf/pgs/380.pdf
>
> Grant KZ1W
By in large, almost every ham item I see is under designed mechanically (not
just towers). We get away with things because, we’ll, we accept a certain
amount of failure, and we aren’t willing to pay the cost.
Look at tower footings. We go with the drawings, but most have a footnote about
unusual soil etc. How often do you hear of a ham actually getting a proper
engineer who knows towers to get a soil sample, and design the right footing
and anchor system. We go by “it works for the average” or “it worked for my
Elmer”
Oh, I understand why ($$$$$)
You bring up polymer bearings. That has been one of my pet “why do we still do
this?” things for a while. Rotors, thrust bearings, tower pulleys (really
sheaves) etc with ball or even metal plain bearings. Guys, in loading,
intermittent motion use, ball/roller/needle bearings were state of the art, in
1940. Here we are 80 years later, and there are a lot of better choices,
particularly if out in the weather, without someone lubricating the bearing on
a regular basis.
We tend to abuse our wire rope (those lift cables are technically wire rope).
If you are seeing broken strands, or rust, or both, there IS a problem, and it
is time to look at replacing the same. There is a reason wire rope lubricants
exist, as well as protectants. They prevent rust. They help prevent broken
strands as the strands rub over each other. Call the companies that make these
products, and ask which you should use, in your case, and do it. Most come in
spray cans. Lower your tower, every wrap on your winch drum, spray the wrap
with enough lube for it to get inside, and continue, then lube what is left.
Inspect and lubricate your sheaves (pulleys). Do it twice a year (say before
spring and fall contest seasons)
While you are at it, inspect your coax, your grounding etc. it isn’t hard to
do, and if you do it on a scheduled basis, it is a lot less stressful than
having to do it when something breaks
--
73 de KG2V
Charlie
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|