[TowerTalk] Rotor Removal

Tue May 25 11:36:09 PDT 2010

I only have 220 pounds including the weight of the mast


Mark N1UK


----- Original Message ----- 
From: "Roger (K8RI)" <K8RI-on-TowerTalk at tm.net>
To: <towertalk at contesting.com>
Sent: Tuesday, 25 May, 2010 2:22 PM
Subject: Re: [TowerTalk] Rotor Removal


> Likewise, but it depends on the weight of the mast and antennas.
> In my system I'm looking at maybe 600# so I simply use one of the top
> braces for the come along.
> I put a saddle clamp around the mast above the bottom bearing with a
> piece of angle bolted to that. I have a hold drilled through the angle
> for a clevis and hook the come along to that. The bearings keep the mast
> centered against any side pull. I only need to raise the mast enough to
> take the pressure off the rotator plus a little for clearance which is
> about an inch.
>
> On 5/25/2010 1:58 PM, David Gilbert wrote:
>> I do a similar thing, but I have a suggestion that may make it simpler
>> and cheaper for you.
>>
>> Drill holes in one face of an 18 inch length of angle iron spaced to
>> accept the bolts from a saddle-type muffler clamp (available from Pep
>> Boys for a few dollars),
> Although they are more, I use saddle clamps with SS bolts and an
> aluminum saddle from DX engineering.
> I've had poor luck using the muffler clamps rusting badly to the point
> of twisting off the threaded portion if they are left in place.
> Even if interrupted and you have to leave them up there for a week or
> two they still get messy.
>>   and use that homebrew assembly instead of a
>> second thrust bearing on the lower bearing plate.  I use angle iron that
>> is about 1.5 inches on each face, but you could use 2 inch angle iron
>> and have room for two muffler clamps if you want the additional safety
>> of redundancy.  The muffler clamps will work fine to keep the mast from
>> sliding down while you remove the rotor, and the other end of the angle
>> iron can easily be secured to the bearing plate with a C-Clamp to
>>
> You can drill it to match one of the holes for a sure fire hold.
>> prevent the mast and antennas from pinwheeling in the wind.  If my
>> description here is poor, let me know and I'll send you a picture of 
>> mine.
>>
>> Another advantage of using the angle iron and muffler clamp idea is that
>> you should be able to get a crow bar between the muffler clamp and
>> bearing plate to recover any minor slippage that might occur in the
>> process of removing the rotor.  I doubt you'd be able to do that with a
>> normal thrust bearing since they sit flush on the plate.
>>
>> You won't want to leave the thing on the tower when you aren't using it,
>> though, since the muffler clamps and bolts can rust rather quickly.
>>
> Boy do they ever...<:-)) That's why I went to the SS fittings. I've
> never had one slip.
> Normally I use a thrust bearing with the bolts loose and well greased at
> the bottom accessory plate. The only time those bolts get tightened is
> to hold the rotator. I also tighten the bolts in the top bearing once
> the mast has been lifted so it is held it two spots. Never seize or
> lubing the bolts is important as I had one TB-3 that took nearly a month
> for the PB-Blaster to work in to the point where I could get the bolts
> out.  (I replaced them with SS)
>
> However, the safest approach would be to lift the mast high enough to
> put a block under it to prevent any injury should it slip.  As I said,
> I've never had one slip, but that comes with no guarantee that it won't
> happen next time. Just a 2X6 or 2X8 through the tower or a piece of
> steel channel wide enough for the mast to set in it will do the job.
> This can also take the load off the come-along.
>
> 73
>
> Roger (K8RI)
>> 73,
>> Dave   AB7E
>>
>>
>>
>>
>> On 5/25/2010 8:32 AM, Mark Robinson wrote:
>>
>>> I am thinking about possible rotor maintenance on my new tower. I will 
>>> be
>>> lifting a 22 foot mast and antenna stack onto the tower with a crane and
>>> nesting it 4 feet or so into my Rohn 45 tower. I will have a thrust 
>>> bearing
>>> on the top and an Orion 2800 rotor 4 feet below the top thrust bearing.
>>>
>>> I am thinking of setting a second bearing plate just above the rotor 
>>> which
>>> will be about 4 feet below the top thrust bearing. I will have a TB3 
>>> bearing
>>> on it. I may well lift this bearing off the plate and clamp it to the 
>>> mast a
>>> few inches above the plate so that I don't have alignment issues. The
>>> bearing just sits in the air above the plate. When I want to remove the
>>> rotor I should be able to lower the bearing, bolt it to the plate and 
>>> add a
>>> clamp to the mast so that the mast rests on this bearing or will the 
>>> bearing
>>> stop the mast sliding down. Some sort of u
>>> bolt or a saddle clamp should work. The stack and mast will weight about 
>>> 220
>>> pounds.. I should be able to remove the rotor
>>> then with the mast held in place.  Yes it's more money but it makes it
>>> possible to remove the rotor and repair it without dealing with the 
>>> stack.
>>>
>>>
>>> I am still thinking this out but I want all the pieces fabricated and
>>> checked out with the tower on the ground first
>>>
>>>
>>> Mark N1UK
>>>
>>> _______________________________________________
>>>
>>>
>>>
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>>>
>>>
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