Hans,
I believe that sort of adaptation, together with hand rotation of the
antenna by means of a chain drive and an old car steering wheel above the
operating position, the antenna aloft, on an old wooden water tower, was
in use, in the USA, back in the late 1940's........how things have
changed.
73, John. G3JVC/GM3JVC.
> What about using the rear axle (or half) of a car (or truck)? At least the
> strength would be there and some water-proofing too.
>
>
> Hans - N2JFS
>
>
>
> -----Original Message-----
> From: John E. Cleeve <g3jvc@jcleeve.idps.co.uk>
> To: K8RI <K8RI-on-TowerTalk@tm.net>
> Cc: Towertalk <Towertalk@contesting.com>
> Sent: Thu, Feb 28, 2013 4:42 pm
> Subject: Re: [TowerTalk] Thrust bearings
>
>
> Hello Roger
>
> The scrap aluminium tube I used has a wall thickness of about 0.75 inches,
> the object being try and find bearings/materials that I could fairly
> easily fit together in order to fabricate the housing with minimal machine
> shop access. Having done the bench metal cutting etc. I did get the edges
> etc. cleaned up by asking for help from a local machine shop, otherwise,
> the original 1979 bearing assembly was a true amateur radio "kitchen
> table" product.
>
>
> 73, John. G3JVC/GM3JVC.
>
>
>
>
>> 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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>>> TowerTalk@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>
>>
>> _______________________________________________
>>
>>
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>>
>
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