[TowerTalk] Thrust bearings

[K8RI]

On 2/28/2013 4:41 PM, John E. Cleeve wrote:
> Hello Roger
>
> The scrap aluminium tube I used has a wall thickness of about 0.75 inches,

Now THAT is "thick" and certainly substantial<:-))

73

Roger (K8RI)any10cats

> 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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>>>
>>>
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>>
>>
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