In a message dated 96-06-11 23:35:21 EDT, you write:
>I haven't used the TB-3 before but plan to in a new installation with a
bearing-top 55G >tower. Are these thrust bearings to be packed with
greasebefore installation? Can >they be?
Hi, Ralph --
The Rohn TB-3 is a non-lubricated thrust bearing. Since it only turns 1
RPM, the demands on it are only moderate. It's a race and ball bearing
arrangement and is one of the few bearings suitable for outdoor use.
>Are there any preferred alternatives?
Sort of. A couple of the other tower manufacturers have thrust
bearings available but they tend to have a different drill bolt pattern than
the Rohn so using one on a Rohn plate would require some accurate drilling.
DO NOT USE those machine shop pillow blocks that are commonly found. You
can identify them because they use an allen screw to secure the mast. They
are also non-galvanized. They will rust up in a couple of years requiring
drilling out of the rusted allen screw and lots of screwing around to get it
apart from the mast/tower. To test the suitability of using a material
outdoors, put it oustside for a couple of weeks and see how it does. If it
starts rusting, throw it over the back fence or recycyle it. Just don't use
it.
73, Steve K7LXC
TOWER TECH -- professional tower supplies and services for amateurs
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