This is not re-opening the "thrust bearing vs rotor supporting the weight"
thread. Questions are slightly different. I have two crankups with 7
1/4" bolt to bolt
holes for thrust bearing, so pondering solutions. (I know there are "do
nothing" suggestions)
1) The ~$100 price tag on a bunch of ham-provided "thrust bearings"
seems way overpriced
compared to other available channels
2) why aren't shaft collars used in addition?
detail:
Looking at a bunch of the flange bearing type "thrust bearings", like the
US Towers TB-2US, Triex TB-2, or ?? from AN Wireless
It seems like they all are standard 2 hole flange bearings, painted cast
iron,
with concentric locking collars, inside bore
of either 2 1/16" or 2 3/16"???, with 7 1/4" bolt to bolt centers (5/8"
bolts).
(from pictures plus I have a us towers TB-2)
2" bore would seem too close tolerance for what's going on in the typical
setup. 2 1/16" is a bit harder to find. AN Wireless says they have 2
1/6" bore. Some
on towertalk have mentioned 2 3/16" bore. Don't know what the others
provide.
Surplus Center has a bunch of 2 3/16" bore for just $22.95
($34.74 w/shipping to CA)
Item# 1-211-35-2-C
at
http://www.surpluscenter.com
I suppose having the flexibility to tweak/shim the mast might be a good
thing. So maybe
2 3/16" bore is a good thing.
I realize they're not corrosion resistant, but it seems like lots of
people use them.
Stainless steel variants are available. If people really cared, I
suppose they would use
them, but they don't. Although available, I'll assume not worth the
extra $$.
Adding a 2 piece shaft collar on the mast above the bearing, would seem
to add a lot
of axial load capability. I like that idea when climbing the mast.
(rather than all/most just on the
rotor shelf below)
McMaster seems to have a bunch of 2 piece shaft collars
with 2" bore, and stainless, aluminum or plated available. (plus others)
2" bore Aluminum might deal with tolerance issues nicely, $17.84.
Shaft collars used on top of the flange bearings seem like "a good
thing". How
come I've not heard more on towertalk about such I think. I've read all
the arguments
about having all the load on the rotator etc.
But what about situations like climbing the mast?
Yeah you can use a set screw tightened on a pipe flange below the top plate,
but that's not much extra axial load support.
Thanks,
Kevin
KE6RAD
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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