Yaesu thrust bearing???

[Tom]

Hi
Has anyone experience with the Yaesu thrust bearing? I am helping a friend
and I climbed his tower, his rotar was not spinning his about 70 lb beam and
mast around. It is sticking or stopping in some spots. Then the motor just
doesn't have the power to push it. I noticed that the entire weight of the
masting and antenna was sitting directly on the bell housing of the rotar. I
was able to losen those eight set bolts on the thrust bearing and found it
very difficult to swing that antenna around. First I had to pinch the
masting about a 1/4 inch higher off sitting on the rotar. I needed a pipe
wrench and even then I used heavy force to spin it. I then tried the rotar
without the bearing and it does its 360 degree spin.

Seems that bearing or system wants to stop in the same spots. The darn thing
looks so gutsy and heavy duty that I am wondering why it failed (if that is
the failing part) after only about 15 years in Ontario's weather.

Is there any way to correct that bearing? I cannot see any grease nipples or
any ways to get grease or anti siezing compound in there, do the bearings
get damaged? or does its guides get damaged? Are those rotors able to handle
the weight and spinning without that bearing? How can you replace that
bearing without pulling the antenna off? That is a big antenna, all band
beam and it is huge. Is there a thrust bearing of some kind that could go
over top of the old one? Or one that can be added about a foot down on the
first section of tubular tower?

Any ideas or expertize would be most appreciated,

Thanks

73s

[Jerry Stuckle]

I'm not familiar with the Yaseau thrust bearings (it's been a long time
since I did tower work), but in general it sounds like your thrust
bearing is seizing up. In a case like that, the thrust bearing must be
replaced. Greasing it *might* help for a short time, but chances are it
has already been damaged.

Unfortunately, the only way to correct a seizing thrust bearing is to
replace the bearing. Adding other bearings above or below won't stop
failed bearing from seizing. And to do this you must remove the antenna.

--
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Jerry, AI0K
jstu...@attglobal.net
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[David]

At Sat, 19 Oct 2013 07:43:27 -0400, Tom rearranged some electrons to
write:

You did release the brake before you tried to spin it, didn't you?

[Paul Drahn]

You didn't give any model numbers. If it is similar to my Create rotator
model RC5 and thrust bearing, I have the 1982 manual. My rotator and
thrust bearing have had very little use, mostly setting in the garage.

Last year I decided to disassemble both and change grease. The thrust
bearing has been out in the weather and dust for years, along with the
tower, stacked up under the trees.

The thrust bearing could not be turned. So, I disassembled it and
discovered it was full of dust. There is NO dust seal on the thing. I
cleaned it and greased it and now it turns fine.

The manual is very clear about the thrust bearing. It it not there to
support the mast and antenna. The rotator has a very capable thrust
bearing in the form of a single ball in the center. I verified this when
I disassembled the rotator and changed the grease in it.

The manual clearly states the thrust bearing is there to control the
horizontal thrust from the mast. There should be a few thousands
clearance between the four bolts on the thrust bearing and the mast. An
alternative is to use compressible material between the mast and bolts.

I have had many people argue with me, but that is what this manual states.

In your case, the thrust bearing needs to be removed and serviced. I
don't know how you can do this and keep the antenna and mast on the
tower. If you disassemble the thrust bearing still on the tower, you can
kiss at least one of the ball bearings good by!

Paul, KD7HB

[Tom]

Thanks for the infos

This is a friend's system so I don't have manuals or model numbers. I think
the rotar is good. I am darn sure it is the thrust bearing and after surfing
and rag chewing all morning on 2m with the tribal elders we have thought of
a couple ways to deal with this. Now of course they asked me if I completely
spun the bearing when I was at the top while it was unhooked from the
masting and I did not do that. What I did was backed off the 4 set screws on
one side (half) and that freed the masting, so he worked the rotor box in
the shack and the antenna did its thing. When I re tightened the bearing and
losened the rotor I couldn't easily spin the antenna and masting. Needed the
pipe wrench. So IMO it must be the thrust bearing. Of course my elmers want
me to losen again and spin by hand the thrust bearing to completely confirm
it is the sticking part. Easy enough to do on our next sunny day.

The best option so far is to move the rotor and push up a new thrust bearing
and at the first step down from the top. use flat bar to make a criss cross
and slip in a new thrust bearing at that position and just back the screws
off the old one and leave it there. We thinks that might be the answer, once
I confirm 100% for our hill top council that is the failing component.

The previous climber left that entire weight of the system on the rotor then
tightened the rotor plates and then tightened the thrust bearing last. So
possibly this could have initiated the gutsiest looking thrust bearing I
have seen to fail. I am surprised such a heavy duty thrust bearing failed
after only 12 years. I think its model number is Yaesu 8GS-065. The pipe
alignment all looked good, when viewing it from the ground from all three
directions against the towers three legs, the middle masting looks straight.

Thanks again, 73s








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