Steve,
Having had one LM-470 crank up cable fail because a pulley bearing had
rusted and would not turn, and the added stress caused the failure. Sealed or
not here in Florida they get water inside. I also had a frozen bearing on
my current US 589 tower, fortunately it was on the pull down cable and not a
high risk.
Each of these pulley bearings are of the closed , ball bearing design, but
have had water intrusion and rusted. Once rusted it is easy for the
bearing balls to become misshapen and then freeze the pulley - I am sticking
with my recommendation as it has happened to me.
Norm W4QN
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In a message dated 9/4/2012 1:57:44 P.M. Eastern Daylight Time,
K7LXC@aol.com writes:
> So my recommendation is to regularly lube the cables, and rigorously
grease the pulley bearings. Because the pulley bearings are deep within a
'sheave' I recommend drilling a small hole (1/8") next to the pulley mounting
bolt so that a lubricant can be squirted directly into the bearing
It's probably not necessary. For years, UST (and others I'm sure) have
used pulleys with pressed-in sealed bearings so no attention is needed.
OTOH if your pulleys have bushings instead, periodic lubing is a good
practice.
Cheers,
Steve K7LXC
TOWER TECH
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