In a message dated 99-03-20 10:32:04 EST, W4EF@pacbell.net writes:
> I have a heavy duty pulley (1300 lbs working load) here that I was thinking
> of using as part of a tram for an upcoming tower project. My plan was to
> possiblly attach this pulley to the antenna mast and pass a nylon rope
> through it.
> The rope would attach to the a tram pulley riding on a 1/4" EHS cable and
> would
> be used to raise and lower the antennas. Although the pulley is quite
heavy,
> it will
> only accomodate 5/16" diameter rope or cable (1/2 wide pulley wheel). Will
5/
> 16"
> nylon rope be heavy enough to safely raise and lower the antennas (I
> estimate
> the static load to be over 100 lbs), or should I go to a bigger pulley and
1/
> 2" rope?
>
Hmmm. While the 5/16 inch rope (if it's nylon) has a safe working load
of 192 pounds, it is too small to get a grip on while pulling it manually. A
larger rope is much easier to hold onto when pulling on it.
> BTW, the antennas in question are a KLM KT34XA and 40 meter 4 yagi both
with
> the heavy duty (thick) boom material option.
>
OTOH if you used a lawn tractor or capstan winch or other piece of
equipment, then you don't have to worry about grabbing the rope by hand and
your pulley and rope should be fine. Don't forget that you need a snatch block
at the bottom of the tower to change the direction of the haul rope from
vertical down the tower to horizontal so you can pull on it.
Cheers, Steve K7LXC
Tower Tech
Champion Radio Products
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