The TB-3 (and TB-4) are both aluminum races with steel ball bearings.
It is very common for older TB's to have the rumbling you describe since in
wind gusts, the steel bearings can get pounded into the softer aluminum
races. This means the bearing is on its last legs. I wouldn't reinstall it.
## if she doesn't reinstall it, what is she supposed to replace it with ?
Well, if you were just going to use it as a bushing without tightening the 3
bolts, it'd last for years.
## Then u end up with a sloppy fit..and mast will wobble...esp a tall
one. Actually that array solutions swinging side mount uses a 1" THICK
some kind of plastic... like uhmw..but black. If the hole in it was say
2.004... instead of the typ 2 1/16 [ 2.0625"] then no slop.
## A thick, treated wooden bearing would work too. I wouldn't use
a steel, fixed tube.. unless well lubricated.. like roger is planning.
Rotate a galvanized mast on inside a fixed tube.. and u will probably
tear off the zinc plating on the mast...eventually.
Jim VER7RF
The actual value of a thrust bearing is the
subject of some conjecture since most or all of the weight of a mast and
antenna array should be on the rotator.
Cheers,
Steve K7LXC
TOWER TECH
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