That's interesting. With the correct selection, possibly lifetime
bearings..........
I would love to have sheave bearings with a little grease fitting so I
could
grease them as I do the other grease fittings on the tower. We
discussed this
in the past but couldn't come up with anything. After replacing two
sheaves after
they froze up I would like to improve the stock design if possible.
Bob
K6UJ
On 9/1/16 6:36 AM, charlie@thegallos.com wrote:
<snip>
Will take them to my local machine shop and have new waterproof sealed
bearings pressed
in as we discussed earlier.
<snip>
I sort of worry about the idea of any kind of ball/roller bearing in what
is basically a static situation
One of the big issues they found in cars was there was more damage done to
a car's wheel bearings when shipping them on trains than actually running
them. The vibrations/shock on the bearings in a fixed location caused all
sorts of issues
Believe it or not, in intermittent motion use (we aren't constantly
cranking our towers up and down), Bronze bearings can be great BUT you
have to keep them lubed!!
What is often used today, and properly designed is probably the best is
some of the exotic PLASTIC bearings. Going to one of the thin wall
plastic bushings can give you GREATER load without creep, and will NEVER
have to be lubed. Think of it as "reinforced Teflon", but some of the
plastics are way better than that, all the way up to things like
torlon/vespil etc (which are insanely expensive)
If you are going to get a Sheave re-bushed, I'd look into some of the thin
wall plastic bushings out there, and then bore the bronze to just fit the
new bushing in there, and run that. Never need lube, picking the right
product, and you'll never have an issue
(Picking the right product = knowing the load on the bearing - so if you
know the weight of the tower/antenna etc and the diameter of the
bearing....)
Look at igus.com (just first I found )
Heck, depending on load, something as simple as acetal (aka delrin) or
glass filled/reinforced acetal is probably enough (or even glass/Molly
filled nylon)
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