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
protection.
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.
73
Roger (K8RI)
> such circumstances.
>
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|