In a message dated 4/27/2010 10:15:42 A.M. Pacific Daylight Time,
> I just took possession of a used US Tower Corp HDX-689 yesterday.
What's the deal on the
2 x thrust bearings? Mine are both for a 2" mast. What I DON'T see
is.. any set screws, etc
for either of the bearings. [these are US-tower corp bearings]. I slid
a piece of 2" OD AL
tubing I had handy.. and it slides right through the bearings.. then into
the K7NV prop pitch
clamp... also made for a 2" mast.
> The ID of BOTH bearings appears to be 2 1/16". So there is a
1/32" [.03125"] gap between
mast ..and ID of bearings. So there is a little ..'play' in it. Why
no set screws ??
I was thinking of stuffing a .030" or a .027" thick shim in there.. to
take out the play.
No, the top part of the bearing is a little eccentric. You turn the
top collar until it's snug and then tighten the little Allen screw.
It's one of my least favorite thrust bearings. The Allen screw WILL
rust and then you'll need to drill it out in order to remove the mast or do
anything else with the mast.
> OK, with NO set screws on either thrust bearing... the ENTIRE weight
of mast + yagi's, etc..as is, will be sitting on the prop pitch.
Which is fine with the prop pitch. All rotators should have some
preload on them to seat the bearings. The Orion 2800 wants ALL the weight on
rotator. It doesn't hurt with any other others either.
Which means the purpose of the thrust bearing is to really hold the
HORIZONTAL wind forces which you can do with a bushing or even a piece of
IMO thrust bearings are highly over-rated.
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