Hi Bob – that’s some great information & if OK I’ll echo some similar
experience. Just a word of caution to the readers on the reflector - be
careful ordering KP8 bearings off of ebay – I have five here at my desk that I
bought some years ago and was shipped KS8’s which are spherical construction
and allow the axis of the inside race to pivot along two degrees of freedom –
useless for tower cable pulleys. Guess I need to resell them to someone who
needs them.
Regarding roughness –I have had a few pulley bearings which would not rotate
smoothly because the balls/races either had grit and/or solidified grease in
them and/or they had become pitted from excessive corrosion. One tower I
acquired from an estate apparently had been sitting unused for a very long time
(the cables were quite corroded). I had some luck washing the bearings out
really thoroughly with solvent in the parts washer until they were able to spin
quite freely – albeit with some remaining roughness. When re-lubed
afterwards, they worked fine for the relatively slow speed hoisting
application. There were two, however, that were so rough they would still
bind or hang suddenly when spun by hand at high speed after cleaning & I didn’t
feel comfortable reusing them so I replaced them. Houston Bearing & Supply
here in Houston was able to find suitable replacements for the KP8’s via
special order. The side shields were a little different but they work just
fine. Cost was about $20 each I think around 5 years ago. If I can find the
receipt that shows the mfg. & part number of the replacement bearings I’ll post
that information here later.
FYI for any tower talkers that are needing to re-cable towers and inclined to
DIY - cable crimping tools, bulk cable, cable eyes, & crimp sleeves are quite
economical compared to the cost of pre-assembled replacement cables. I use
copper crimp sleeves (as opposed to aluminum). Be sure to always triple crimp
& verify your crimps are good with a “go-no go” gauge when completed. Suggest
to buy a crimping tool that includes this gauge. Also beware of cheap
Chinese cable… I made the mistake of doing this once and had to recable the
tower again less than a year afterwards…. get your cable from a reputable
dealer.
As always, hope this info is of use to others.
73
Matt
KM5VI
From: Bob K6UJ [mailto:k6uj@pacbell.net]
Sent: Saturday, May 13, 2017 10:39 AM
To: Matt <maflukey@gmail.com>
Subject: Re: [TowerTalk] FW: Replacement worm gear box for TX-472 motorized
tower...
I have tried rejuvenating the pulley bearings that were bad by injecting grease
into the side of the bearings as Matt describes but couldn't get them back to
smooth rotation. I think it depends on how bad the bearings are to begin with.
I have a US Tower HDX589 motorized tower and I called US Tower to find out
how much for new bearings. They only sell the entire pulley assembly with
bearing installed. Attached is their quote for the two sizes of pulleys.
(ouch)
I didnt feel like paying over $100 for each so I found just the replacement
bearings for $25 apiece on EBAY. They show up all the time on EBAY.
The bearings are Fafnir # KP8FS464 I'm pretty These bearings are used
in all the US Tower crankup pulleys. They old bearing needs to be pressed out
and the new bearing pressed in. I was able to do this with my bench vise, not
that
hard to do.
73,
Bob
K6UJ
_____
From: Matt <maflukey@gmail.com <mailto:maflukey@gmail.com> >
To: towertalk@contesting.com <mailto:towertalk@contesting.com>
Sent: Friday, May 12, 2017 9:50 PM
Subject: [TowerTalk] FW: Replacement worm gear box for TX-472 motorized tower...
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
<mailto:towertalk-bounces@contesting.com> ] On Behalf Of Rick
Stealey
Sent: Friday, May 12, 2017 5:20 PM
To: towertalk@contesting.com <mailto: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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