[TowerTalk] Thrust Bearing

maflukey at gmail.com maflukey at gmail.com
Sun Dec 27 05:59:56 EST 2020

As an alternative suggestion....  I have been using flange mounted pillow
block bearings as mast thrust bearings  - first time was about 20 years ago.
IMHO they are typically plenty strong - ratings are something like ~6500 lbs
static radial load and ~ 2500 lbs of static axial load.   Cost was about $35
then, probably $50+ now, but they seem to last forever if you keep them
pumped full of grease and protect them from the weather.  For standard 2" OD
structural steel mast I used 2-1/16" bore bearings.   For 1.5" SCH 160 pipe
masts I used 1-15/16" bore bearings.    Recommend to confirm the mast OD by
measurement with a mic or dial caliper, especially if you are using
repurposed masts...  For a weather shield I used silicone bellows type
plumbing vent roof jack seals that I attached to the masts just above the
bearings with an automotive worm clamp.   The bottom of the bellows sat just
high enough over the top plate of the tower so as not to rub but completely
covered the bearing housing....  don't forget to slide the seal over the
mast before you install it or you have to start over - hi.   Also suggest to
put a coat of paint on the mounting side of the bearing block or it will
rust and/or interact with the galvanized top plate surface.   My larger
tower accepted the 4-bolt bearing flange by re-drilling the top plate but
three smaller towers I had to fabricate adapter plates.   I used 1/4" mild
steel plate for the adapters.  PS - pillow block bearings pivot in their
housings so be sure to keep the bottom end of the mast restrained whenever
it is disconnected from the rotor.

73 & Happy Holidays!

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