One additional comment re bearings, in reconditioning an LM354 TriEx I
found the bad bearings were Boeing surplus aircraft control cable
sheaves. Marked with "Boeing + part numbers" and with a pressed in ball
bearing uniquely made for them. Apparently TriEx bought a big lot of
Boeing surplus. Not to be found in any bearing catalog, but there they
were on ebay!
So unless you are lucky on ebay or can machine new sheaves or machine
them to fit stock bearings, the clean and grease fix is an probably the
best alternative and should last a few years. While not as low friction
as ball bearings an oilite sleeve bearing could be machined to fit and
won't rust or seize up.
Grant KZ1W
On 5/12/2017 21:49 PM, Matt wrote:
Just wanted to echo Rick's comment. I have 4 older crank-ups (2 Triex and
2 UST) and all have had pulley bearings go dry over the years. The only
failures I have seen develop with gear boxes have been leaking seals. One
of my towers was, however, acquired with a gear box that was dead on arrival
and had to be rebuilt. Other than that, I have found the gear boxes to be
pretty reliable provided that they are not allowed to run out of gear lube.
Regarding the pulley bearings, replacement bearings are generally very hard
to find, and replacement pulley assemblies are expensive. I have had very
good success reconditioning old tower pulley bearings by drilling a small
hole in the side shield of the bearing and inserting a hypodermic grease
needle (available at your local auto parts house) to flush out the old
grease with new grease. If the bearing won't turn at all, try running it
under a parts washer while working the races back & forth to loosen up the
stiff grease. Then flush out the old grease with new as described above.
If you do need replacement bearings, I suggest trying a bearing supply
house. There is usually one in most larger cities. It will be best to
remove the bearing from the pulley and take it to the parts counter unless
you have a set of micrometers or a good dial caliper to measure the old
bearing dimensions accurately.
Most pulley bearings simply drive out of the housing (they are press fit &
peened in place) - look for a snap ring first & if you don't see one then
it's a good bet it's press fit. Beware that many pulley bearings can only
be removed from one side of the pulley. If you drive it in the wrong
direction you can shatter the retaining lip on the pulley bore which will
trash the pulley. After reinstalling the replacement bearing, be sure to
peen the pulley from the installation side around the circumference of the
outside race to help securely retain the bearing in the pulley.
Hope this info is useful & good luck.
73
Matt
KM5VI
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Rick
Stealey
Sent: Friday, May 12, 2017 5:20 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Replacement worm gear box for TX-472 motorized
tower...
Do you know the problem is not the pulleys?
I have the same tower. 7 pulleys were bad. Motor stalled.
Rick K2XT
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