Thrust bearings (like baluns) seem to be one of those things that create a
lot of confusion in the ham community. They are used to keep the antenna
centered on the rotor to eliminate side strain, or to take compressive
strain off the rotor, or both, depending on who one talks to about them.
I'm putting a T-8 on a HG-52-SS that does not have a thrust bearing on it
at the moment. Everything I read about CDE rotors indicate that there is no
need because the rotor can handle the weight if a short mast is used
minimizing the leverage effect. Other readings say to use one because it's
important to hold the antenna weight off the rotor. Many thrust bearings do
not have any way to hold the antenna off the rotor seemingly to be only for
keeping the mast centered in the rotor. That appears to me the purpose - to
minimize any lever-like lateral pressure on the rotor generated by the
antenna and mast induced by wind.
There are lots of HG-52-SS towers in ham service and apparently no factory
thrust bearing available, and while the Rohn TB-3 and Array Solutions
version (and others) are adaptable, they require a few holes to be drilled,
not necessarily an easy project 20+ feet off the ground.
Is a thrust bearing really needed or is it something that most of us do
just because?
Mike, k5wmg
Fast cars, slow boats, good dogs, and summers off to write
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