Several times I have mentioned the rotator sticking over the past few years.
The previous winter (04) I discovered the TB-3 thrust bearing had worn to
the point that the upper race was setting on the lower casting and
preventing the whole works from turning. Loosening the centering bolts in
the bearings allowed the mast to turn and things appeared to be fine...
until late this past winter (05). It started sticking again, but the
weather was not favorable for tower work for a while and this has been a
very busy Spring and early Summer.
Sunday I managed to get a couple of gophers...er go-fers for help and
tackled the antennas and rotator. (There really wasn't a lot for the
go-fers to do except lower the rotator, go-fer forgotten tools, and act as
safety observers which is reason enough)
I loosened the rotator to mast clamp and then using a come-along, raised the
mast. I then tightened the thrust bearing bolts to hold the mast and took
out the rotator.
The next step was to go back up on top and cut as much of the pigtails loose
from the mast as I could reach. Then it was back to the come-along to lower
the mast. I managed to lower it *almost* enough to get at the 6-meter beam
before running out of loose pigtails. Unfortunately that was where I ran
out of steam. At my age I'm not quite as durable as I was just 5 or 6 years
So we anchored things in place. Next time I hope to get the 6-meter beam to
the top of the tower and the 144/440 beams removed.
Taking that big rotator apart (PST-61) can be messy if you don't have a big
bucket under it. We did and it was still messy, but the bucket kept the
mess to a minimum. Other than the lube looked like black paint the interior
looked pretty good at first glance. First glance also told me that is
rotator certainly has no relation to the spur gear rotators most of us are
familiar with. That thing is *massive* inside. Not only are the output
worm gear and worm gear wheel massive, the end bearings are taper roller
bearings that bear a close resemblance to wheel bearings. It is rated to
support almost one ton and has about 16,500 inch pounds of torque, but I
The bottom bearing, although dirty appeared to be in good shape. However
getting to the top bearing revealed a gooey, grainy, black mess. The top
seal had failed and that bearing had almost disintegrated. Much of the
retainer had dissolved and broken into parts. The only thing holding the
rollers in some places were the inner and outer races. It was these pieces
of retainer getting under the rollers, or the rollers sliding out of place
that was causing the rotator to bind up.
The distributor (Jay) has been very helpful in getting this thing apart.
I've now reached the point where it's time for a hydraulic press to get the
shaft out of the gear and the top bearing off. IF I don't brake anything
the only parts needed will be the two bearings and oil seals.
That big bronze gear appears to have been cast onto the steel inner support.
As the bronze gear is thicker than the support it means supporting the steel
flange rather than the brass when pressing out the shaft. The whole works
has been soaking in PB blaster for the last two days.
If any one is interested AND has a high speed internet connection there are
three LARGE high resolution photos of the insides at
http://www.rogerhalstead.com/Gears.htm I emphasized the large as they are
about 750K each. Maybe I'll get a chance to replace them with 800 X 600
images which are only about 100K each.
BTW my address has changed and the only accepted sender to this one is the
reflector. Direct replies/e-mails should go to an address on my home page.
Sorry about the round about method, but the old address here was getting
more spam every day.
Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
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