N4NW wrote:
> The problem with the bearings you indicate is that they are not
> 'thrust bearings!"
>
> A thrust bearing is a particular type of rotary
> <http://en.wikipedia.org/wiki/Bearing_%28mechanical%29>bearing. Like
> other rotary bearings they permit rotation between parts, but they
> are designed to support a high
> <http://en.wikipedia.org/wiki/Axial>axial load while doing this.
>
> 73's
> Tom - N4NW
true. but I think most "ham" thrust bearings are regular old radial load
ball bearings with the races parallel to the shaft. A standard bearing
will take a fairly substantial axial load, and the rotation rate and
duration in an antenna application is miniscule compared to any normal
shaft sort of application. The rotation rate is what? a few RPM?
In fact, it might be that the radial load is higher than the axial load
in ham applications.. put a long mast with a big antenna on it in the
wind and you develop a fairly high radial load. The axial load is just
the weight of the mast and antennas... a few hundred pounds perhaps,
which is pretty small for a bearing that is taking a 2" shaft, no matter
how the balls and races are arranged.
For ham applications, a decent BUSHING made of something like HDPE
that's UV resistant might be as good as anything else. A half inch thick
sheet of HDPE (aka a plastic cutting board) would be a good start.
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