In a message dated 98-12-22 09:27:56 EST, jimi@designet.com writes:
> 3. If a thrust bearing breaks what do I do?
Well, you dismantle everything and then reassemble it.
The instance of a thrust bearing 'breaking' is so remote as to be a non-
issue. More likely is that the races will wear down and not turn freely. A
Rohn thrust bearing should be good for 10-20 years. There probably won't be
any vertical weight on the bottom bearing so the top one is the most likely to
have problems.
You didn't mention what kind of antenna system is going on this tall
mast. Did you check your county windspeed rating at www.championradio.com?
Have you run mast calculations?
>
> Why not mount the thrust bearings on the UNDERSIDE of each of the
> mounting plates? The Rohn TB-3 appears to operate just fine upside-down.
> I'd use big, wide washers on the top to help distribute the downward
> forces across the mounting plate. Wouldn't this substantially ease the
> removal of either thrust bearing? Taking the upper bearing off by bringing
it
> down to the rotor sounds much more appealing than taking it off over the
top!
>
Are you going to mount the bearing with the top UP but spaced out below
the accessory shelf? You cannot use the thrust bearing in an inverted
position. Per my comment above, I wouldn't worry about the bottom bearing
replacement or coming up with some non-standard installation method.
What about this? How about NOT using a thrust bearing on the bottom
accessory shelf? All you really want to do is to capture the mast and keep it
from flopping around. The hole in the accessory shelf will accomplish this
with no thrust bearing but still allow you to replace the rotator, etc.
Cheaper too. Just a thought.
Cheers, Steve K7LXC
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