[amsat-bb] Re: Yaesu G 5400 elevation rotator quit working

i8cvs domenico.i8cvs at tin.it
Thu Oct 29 19:44:53 PDT 2009

----- Original Message -----
From: "John" <jcrowell at centramedia.net>
To: <amsat-bb at amsat.org>
Sent: Wednesday, October 28, 2009 3:50 AM
Subject: [amsat-bb] Yaesu G 5400 elevation rotator quit working

> My Yaesu G 5400 Elevation rotator decided to quit working Friday morning.
> I could press the up and down buttons and hear the motor running but the
> antennas would not move.
> After being gone out of town for two days, I decided to try it again
> Sunday night.
> And to my amazement, it worked.  The antenna moved.
> Anybody have any clues as to why this happens and what to do to fix it?
> Thanks,
> John C.
> Pampa, Texas
Hi John, KE5GFJ

You probably are in trouble with the Elevation rotator for the following
reason :

Each bearing is composed by 20 ball bearings size 0.312 ( 5/16 inch ) and
a bearing holder.

One groove for the balls is casted into the aluminum boom shaft tube and
the other groove is casted into the aluminum rotor housing

The bearing holder is a stainless steel toothed ring with 20 teeths and
the purpose of it is to keep the 20 balls separated each other while holding
the lubricant grease between them and lubricate the grooves during rotation
preventing in addition the wather to enter the rotor housing from the

The problem here is that the balls are not in contact-to-contact each other
but they are separated each other by the teeths of the bearing holder in
the sequence  O-O-O-O-O-O-O............ and so on.

In this condition the vertical radial force generated by the weight of the
antennas is not completely absorbed by the balls but is applied as well
over the teeths of the bearing holder and so the 20 balls will be forced to
separate away one from the other.

The load of the antennas is responsible to wear out, to deform and to cut
the teeths of the bearing holder but as soon only one or two teeths are
broken then the distance between the balls increases so that the big
assembly tube gear has room to fall down a little bit into the grooves.

In this condition the distance between the assembly tube gear and the
internal pinion increases up to a point that to engage the big assembly
tube gear into the pinion fails.

If this is your case the motor runs in both directions but when the wear is
at the beginning than the antennas becomes stuck time to time.

To cure this problem and prevent damages to pinion and to the assembly
tube gear I have removed the bearing holder and I have filled the grooves
with black molibden grease adding in it  I do not remember exacly if two
or tree more balls of same size and this was made in order to replace the
room originally occuped by the teeths of the bearing holder.

My modified rotator without the bearing holders and more balls is actually
running with no problems from several years now.

73" de

i8CVS Domenico

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