On Mon, 23 Jun 1997 02:40:10 -0400 (EDT) FrankVanderZande
<frank@fortress.net> writes:
>
>Many years ago I toured a INCO nickle processing operation.
>There I saw huge rotating drums (well in excess of 100 tons)
>crush ore. The center shafts of these drums were not rotating
>in ball bearings but in blocks of wood that had been soaked in oil.
>
>Since I saw that, I've always thought that would be a good way
>to handle masts. Place a block of oil soaked wood in a metal
>frame on top of the tower and drill the hole to match the mast.
>
>Anyone doing this?
>
> - Frank VE7AV frank@fortress.net
>
YES, Rohn has had a hardwood bearing in their catalog for as long as
I can remember. For short masts and single medium to large Yagi, I see
NO reason to use expensive bearings. This bearing mounts on top of the
flat top section. No bearing is required for the pointy top sections.
The HAM series rotors are designed to carry several hundred pounds of
vertical load. Removing this load with a single bearing on top of the
tower
is counter-productive. The lack of a vertical load forces the rotor to
carry the
side load (resulting from the mast pivoting at the bearing) WITHOUT any
vertical force to keep the bearings centered in their races. This
actually
increases wear on the rotor!
I have a reconditioned HAM - M that has been in service for over twenty
years without a problem. Even the position indicator pot is still
working!
This rotor carried a 2 element quad and 40M rotary dipole for the first
10 years and now carries a TH6 with no bearings what-so-ever.
de Tom N4KG
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