[TowerTalk] Grease for Rotor bearings

[Roger Kissel]

I've seen this grease/no grease thread for years and never gave it much thought. But, I now have to wonder why anyone would design a bearing with an aluminum body/race ?  The reason I say this is that I took down a tower several years ago that had a TH6DXX on a TB3.  The system had been idle for several years with the antenna rocking back and forth the whole time. Even tho the brake on HAM-M was set there's still some movement. As a result, the bearings ground into the race and dug out pot holes to the point that the bearing would not turn at all.

IMO, they should have designed in a grease zerk and recommended it be used.

When you cut or file aluminum it only takes a short while before it oxidizes. Aluminum oxide is extremely hard (that's what they use for sandpaper) and when the steel balls run over it, it breaks the oxide apart, giving you grinding compound. During the idle period, the bearing ground itself to death.  Had there been grease in the race, it might have slowed down the self-death of the assembly.

So at this point the ROHN engineers and I are at odds. But I'm not a mechanical engineer, nor am I a lubrication engineer, nor am I a metallurgist.  (I only play those on the internet, ya know....)  Granted the bearing tolerances were so  sloppy that contaminants will not be of great significance and even tho it turns so slowly, after what I saw with this one, I would not consider operating it dry. Granted, many greases dry out over the years so something like a synthetic grease should be used.

What I did, since the bearing was of no use/value in its condition, was to disassemble it and welded up the chewed up races so I can recut the races in my machine shop. If it works, I have a decent bearing.  If it doesn't work then I'll use a sealed steel bearing when I put up my next tower.

RogerK
KC8HZ


> Message: 2
> Date: Thu, 13 Oct 2011 13:42:39 -0500
> From: Bill Aycock <baycock2 at centurytel.net>
> Subject: Re: [TowerTalk] Best Grease for Rotor bearings ?
>
> I just looked at the Rohn catalog page for the TB3 and TB4 and there is
> no note about Lubrication. This was the older Rohn catalog that Champion
> used to furnish. The bearings are in the accessory pages at the end of
> the 25G section.
>
> Bill--W4BSG
>
>
> On 10/12/2011 10:26 PM, jcjacobsen at q.com wrote:
> > Doug has a question:
> > ----- Original Message -----
> >
> >
> >
> > Would either of you gentlemen please provide for me the instructions from Rohn that states that their TB-3 thrust bearings are to be run dry. I know that they are sold dry. I am looking for facts from Rohn that say that these bearings should not be lubricated. I am not interested in any information except from Rohn.
> >
> >