I built a rotor "shelf" to mount on top of the AB-621. It is essentially a
cage made from 1/4" Al sheet for top and bottom (12"x12", I believe) with
1" Al rod at each corner connecting the top and bottom. On the bottom, a
chunk of solid Al rod big enough to fit inside the 'nose piece' that comes
with the AB-621 was bolted to allow the cage to sit atop the mast. I added
some Al square tubing 'angles' on the bottom to clamp to the outside of the
'nose piece' with large hose clamps. Admittedly, this is some redneck
engineering to prevent the whole contraption from rotating, but it works
(or at least has for about 15 years). Bolt holes added to the bottom plate
for the rotor to mount, holes in the top plate for the mast and to mount a
thrust bearing. The design is a bit heavy and maybe overkill. But it's
lasted for a long time with no issues.
73, Mike N4GU
> Message: 1
> Date: Sat, 28 Feb 2015 07:49:38 -0500
> From: "Ed G" <ed.n3cw@gmail.com>
> To: <towertalk@contesting.com>
> Subject: [TowerTalk] Thrust Bearing for 621/577 Military Masts
> Message-ID: <7419A78ACCE0449A810B612552B41A4C@SHACKXPS>
> Content-Type: text/plain; charset="us-ascii"
>
>
> Hello,
> Has anyone on the list ever tried to design or build an assembly that
> would clamp on the top of an AB-577 or AB-621 mast and provide for mounting
> of a thrust bearing, perhaps about a foot above the top of a rotator
> (Tailtwister for ex)? I'm trying to envision a way to transfer some of the
> side wind loading from the rotator itself to the mast.
> --Ed--
>
>
>
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