In a message dated 8/11/01 1:57:55 AM Pacific Daylight Time, na6t@mcn.org
writes:
> Does anyone make a waterproof thrust bearing for the LM-470 triex
> tower. I've used the three bolt mounting type at the top of the tower and
> also inside the top section at about 6' (to take the load of the
> rotor). I've been using a 'generic' type thrust bearing and it seems
that
> they start rusting at the rollers in 5-6 years. I've tried the common
> cures of keeping waterproof grease in them, tried putting the 'plumber's
> friend' rubber over the top to shield the bearing, etc.
How about a thrust bearing that doesn't need greasing and some of it
won't rust? The Rohn TB-3 (2-inch) is pretty good in this respect because it
has al aluminum body and bearing races. The bearings are steel but the
combination will last for 5-10 years with no maintenance.
If you need to be greasing a thrust bearing, it's probably not the right
one for a ham tower outdoor application. Machine shop pillow blocks are best
left in the machine shop (they're easily identified by the presence of ONE
Allen screw for holding the mast and has a Zerk fitting for greasing). These
are not typically very good for outdoor use - they rust.
This begs the question of what does your system have that requires a TB?
For small to mediums antenna installations, rotators are perfectly capable of
supporting a mast and antenna(s) without a TB.
Sure, it's a 4-hole TB but shouldn't be too tough to mount.
Cheers, Steve K7LXC
Tower Tech
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