In a message dated 6/18/2008 10:36:36 A.M. Pacific Daylight Time,
wc1m@msn.com writes:
>> You need to jack up the mast just far enough to remove the rotator and
>> you'll be good to go.
> OK, that brings up something about which I've been curious: exactly how do
you jack up the mast? Someday I'll have to do that to get my Orion rotor out
for service, and I can't quite picture the process.
> I'm assuming you attach a come-along cable to the mast and hook the
come-along on a tower rung. But where and how do you attach them?
Well, one end goes as near the top of the tower (rung or nylon sling)
and the other end attaches to the mast with a nylon sling. I use nylon sling
chokers to grab masts and other odd shaped items.
> I have two thrust bearings, one in the top plate and one in a plate
between
the top plate and rotor shelf. There's about 5 feet of mast in the tower,
with about 3.5 feet of it above the middle thrust bearing plate. The
come-along cable would have to be attached between the top and middle thrust
bearing plates. That doesn't leave a lot of room to attach the come-along to
the tower above the point of attachment.
You're right. It'll still work okay - you're not trying to lift the mast
very far. An inch or two is all you need to do a rotor swap.
> Seems to me a better idea is to run the cable up from the mast to a pulley
attached to a rung, and from there down to the come-along. The higher the
cable can run before encountering the pulley the better. Otherwise, the
cable will be pulling sideways more than up.
I'm not sure how your scheme relieves the slight sideways pull but it
sounds okay. It's a good idea if you don't have much room at the top of the
tower plus it gives you some additional mechanical advantage.
> It's not a problem in my installation, but if you had a heavy mast with a
lot of antennas, wouldn't attaching the come-along and pulley to a rung risk
bending a rung? Would it be better to u-bolt a piece of angle steel between
the legs and hang the come-along from that?
I use nylon slings and carabiners for just about everything so I wouldn't
use a fabricated piece of steel. It's more weight to deal with plus you have
to
fabricate it.
Cheers,
Steve K7LXC
TOWER TECH -
Professional tower services for hams
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