[TowerTalk] Thrust bearings

[K8RI]

On 2/28/2013 3:17 PM, John E. Cleeve wrote:
> Gentlemen,
>
> I have read the thread with interest, and here is my solution. Back in
> 1978, and in order to cope with the likely forces applied to a tower top
> thrust race, I looked at the commercial products available but chose to
> "engineer" my own, making use of roller bearings to provide a  more
> effective solution.
>
> I looked for taper roller bearings with a centre bore of 2 inches or more,
> and by using a commercially available two part metal collar, clamped
> around the antenna support shaft, with the lower edge of the collar
> resting on the edge of the inner ring of the taper roller bearing, as the
> antenna shaft passed down through the bearing, the weight of the antenna
> is transferred to the inner ring of the bearing. The taper aspect of the
> roller bearing performance will cope with any radial forces applied to the
> bearing.
>
> New, taper roller bearings are quite expensive,

I agree but,  I've found wheel bearings  to be relatively inexpensive new.


but a metal scrap/vehicle
> breakers yard will provide a very cheap source, especially if you are
> prepared and able to remove them yourself. The taper roller bearings I
> used, came from the rear wheel hubs of scrapped heavy goods vehicles, and
> they are more than capable of handling the largest antenna related stress,
> and better still, cheap, they cost about $1 each!
>
> Of course, the bearing unit requires a "housing" in order to be fitted to
> the tower top plate, but again, the same scrap source provided short
> lengths of suitably sized, thick walled aluminium tube,

Depends on what you mean by thick walled.  I prefer a substantial 
retainer with the bearing pressed in.  I also prefer an over sixe ID 
with an adapter that has a shoulder,  that is a slip fit on the shaft, 
but pressed into the bearing.  If the shoulder is large enough I can 
drill and tap it, allowing me to lock to the mast to support it for 
rotator removal.

My rotator, a PST-61 has wheel bearings top and bottom so it can 
tolerate long masts through thrust bearings that might pull o the 
rotator due to unequal expansion and contraction with temperature.

73

Roger (K8RI)

  in the form of
> scrap "offcuts" sold by weight. I was able to fabricate a very acceptable
> "product", and fitted with a suitable weather protection "hat", i.e a
> scrap aluminium container lid, and the bearing well packed with grease,
> one such unit has been in position since 1979.
>
>
> Sincerely, John. G3JVC/GM3JVC.
>
>
>
>
>
>
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