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Re: [TowerTalk] Rotatorplate

Subject: Re: [TowerTalk] Rotatorplate
From: K8RI <>
Date: Sat, 17 Dec 2011 13:05:48 -0500
List-post: <">>
On 12/17/2011 12:06 PM, Paul_group wrote:
> On 17/12/2011 14:35, K8RI wrote:
>> On 12/17/2011 5:17 AM, Paul_group wrote:
>>> If the unit is used on a tiltover tower its worth spacing the rotor off
>>> the plate by a few mm to allow drainage and using a temporary cover to
>>> protect everything when horizontal, a plastic fertilizer bag works well.
>> Having used one for quite a few years I'd not be very concerned about
>> having to "bag" the rotator. Unlike the Ham series rotators, they are
>> not open to water ingress.
>> The old ones do rust if water sets in that recess. The rust tears up the
>> top seal, and that is what does the damage. See photos 1 through 4.  4
>> shows the deeply pitted shaft due to water sitting in that recess,
>> after having been cleaned
> Well Roger I have repaired a couple of these, maybe being in an exposed
> coastal area where masts do tend to be laid over for fairly extended
> periods makes a difference, YMMV but I advise an additional cover in
I'd agree for "extended periods". the rotator shaft is high carbon steel 
and rusts easily, so if exposed to the elements for a prolonged period 
they certainly would rust.
I pack that area full of white Lithium grease and would suggest a zerk 
or several small zerks be added to the cover plate so that area could be 
easily  filled with a grease that would keep moisture out and stand up 
to the elements.

That top seal is the only part of the design I don't like. "Most" of the 
parts are readily obtainable at your local auto parts store with the 
exception of the actual worm gears and worm gear wheels.  They 
apparently have changed the design of the large worm gear wheel a bit 
and they are now supported state side.

I hope I word this correctly.  I've been considering, facing off the 
recessed area between the raised lip and seal. Then pressing in an 
Aluminum disk that would be higher in the center causing water to drain 
away from the shaft. Then replacing that top seal with one using a 
"raised lip"  so there would be no place for water to collect. 
Unfortunately due to the way it's assembled you have to completely 
disassemble the rotator to get the top cover off.  OTOH the modification 
would be very easy with access to a metal turning lathe.  There are also 
other ways this area could be reshaped to get the desired drainage and 

BTW I did not coat the bottom of the shaft where the pot couples in with 
Silastic RTV (TM), but rather just "glopped" on a bunch of white Lithium 
grease to protect it. IE, keep it from rusting.  That snap ring is 
particularly vulnerable to rusting if not protected.  Every thing is 
exposed at that point...The end of the large, expensive worm gear wheel, 
the bottom end of the center shaft, and the snap ring that supposedly 
holds it in place.  Some are so tight I don't think they need the snap 
ring as it takes a pretty hefty press to get them out.  OTOH some almost 
come out by hand.

BTW with enough hands and equipment you can remove the center shaft 
without disassembling the rotator housing and that would permit taking 
the top cover off for modification.

NOTE: I am not advocating users attempt to modify the rotator, or even 
take it apart although the linked page is a complete step-by-step 
rebuild.  These are very rugged rotators but they can be easily broken 
if pressure is applied in the wrong place or parts dropped.  That large 
brass worm gear wheel is *expensive* and last I knew was difficult to 
get. There are also some very sharp edges in there at the ends of the 
worm gears.  The machining I'm talking about is done on cast Aluminum 
which by itself is rather fragile and must be done with care.  The end 
caps also support opposing, automotive wheel bearings so nothing should 
be done to weaken them in this area.

Possibly squirting LPS-3 in the top against the shaft under the new 
cover would be enough to protect it although  I think I'd be generous 
with the LPS-3 which is basically a light grease in a pressurized can.


Roger (K8RI)
> such circumstances.


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