So why does a rotator want to have that second thrust bearing?
I wanted two because when you take the rotor out and with only one thrust
bearing you don't have control of the mast horizontally. With two TB you
always have control.
----- Original Message -----
From: "David Gilbert" <xdavid@cis-broadband.com>
To: "jeremy-ca" <km1h@jeremy.mv.com>
Cc: <towertalk@contesting.com>; <K7LXC@aol.com>
Sent: Saturday, August 25, 2007 3:03 PM
Subject: Re: [TowerTalk] Rohn 45 Question
>
> Carl, you pretty much avoided Steve's question. What rotator failure
> mode is minimized by having two thrust bearings above the rotator? Can
> you give any examples of your YCCC buddies that would back up your
> comments? It would be interesting to hear their experiences first hand.
>
> I recently ordered a tower, rotator, and fairly large antenna system ...
> and both of the tower manufacturers I investigated strongly recommended
> against using two thrust bearings (at least if both were secured to the
> mast) for the same reasons Steve mentioned. A single thrust bearing at
> the top of the tower makes sense, but a simple plate inside the tower
> with a hole in it facilitates the task of replacing the rotator (which
> is a separate issue anyway).
>
> So why does a rotator want to have that second thrust bearing?
>
> Dave AB7E
>
>
>
> jeremy-ca wrote:
>> I take it then that you have never experienced the installation of a
>> large
>> stacked array without a crane.
>>
>> Old wives tales? Hmmm, most of those that I know have at least a Masters
>> degrees in an engineering discipline.
>>
>> Plus NE Yankees are not known for spending money frivolously.
>>
>> Cheers Yourself
>> Carl
>> KM1H
>>
>>
>>
>>
>> ----- Original Message -----
>> From: <K7LXC@aol.com>
>> To: <km1h@jeremy.mv.com>; <towertalk@contesting.com>; <john@kk9a.com>
>> Sent: Saturday, August 25, 2007 1:21 PM
>> Subject: Re: [TowerTalk] Rohn 45 Question
>>
>>
>>
>>> In a message dated 8/25/2007 10:00:45 A.M. Pacific Daylight Time,
>>> km1h@jeremy.mv.com writes:
>>>
>>>
>>>> Thats strange. Numerous YCCC and other serious contesters/DXers with
>>>> big
>>>>
>>> stacked arrays have been using dual bearings for decades with a
>>> significant
>>> reduction in rotator failures.
>>>
>>> Reduction because of what? Reduction from what to what?
>>>
>>> What actual mechanical improvement does the additional mid-bearing
>>> make?
>>> More torque reduction? No. More vertical weight reduction? No, the
>>> weight's
>>> already on the top bearing. A psychological improvement? Probably. More
>>> ham
>>> radio old wive's tales? Probably.
>>>
>>> Cheers,
>>> Steve K7LXC
>>> TOWER TECH -
>>> Professional tower services for hams
>>> Cell: 206-890-4188
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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>>
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