On 1/6/13 8:02 PM, Grant Saviers wrote:
My 2 cents, having two HDX589s and a TMM433.
I don't think you need a thrust bearing, if your tower has the welded in
sleeve for a 2" mast. I think this is standard on all the current UST
crank-ups.
The sleeve will handle side loads well beyond the TX438 rated wind load
and your rotator will handle the weight load.
I had a TB3 on 85' of Rohn 25 a while ago, and it failed. If you don't
have a sleeve and need a bearing to handle side (radial) loads then I
think boring a mast sized hole in a top plate of 2" thick MDS Nylon
(Nylatron GS) or UHMW is a better approach. A polymer sleeve bearing
will last a long time at the antenna rotational speeds and loads and
requires no maintenance. Both materials are UV sensitive, but not much
of a worry in 2" thickness, or just paint them. I've found remnants on
ebay at good prices.
White poly cutting boards. Stack em up, run the hole saw through them,
and you've got a great low friction, low speed *radial load* bearing
(which is really what you want, anyway). (actually, I suspect a single
layer is good enough)
http://www.target.com/p/kitchen-3-pc-cutting-board-set/-/A-510239#prodSlot=medium_1_3
http://www.target.com/p/chefmate-poly-cutting-board-white-14x17/-/A-10219387#prodSlot=medium_1_16
http://www.walmart.com/catalog/product.do?product_id=13397991&findingMethod=rr
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