[amsat-bb] Re: Yaesu G5500B Repair

i8cvs domenico.i8cvs at tin.it
Wed Aug 11 00:43:35 PDT 2010

----- Original Message -----
From: "Andrew" <WA9WUA at embarqmail.com>
To: <amsat-bb at amsat.org>
Sent: Monday, August 09, 2010 10:18 PM
Subject: [amsat-bb] Yaesu G5500B Repair

> I need information for my G5500B elevation repair. Its stuck at about 68
> degrees. Reply to direct at wa9wua at embaeqmail.com Any help is appreciated.
> Andy

Hi Andy, WA9WUA

If your elevation rotator G5500B stuck always at the same elevation of
about 68° you have in it a mechanical problem or with bearings or with
gears because no electrical parts or limit switches are involved.

If you look at the G5500B  Instruction Manual you will find the exploded
mechanical drawing with parts numbar and location.

Each bearing is composed by part numbar (33) and (34) made each with
20 ball bearings size 0.312 ( 5/16 inch ) and a bearing holder part number
( 33)

Two grooves for the balls are casted into the "aluminum boom shaft tube"
part number (29) and the other two grooves are casted into the rotor
housing side (1) and side (2)

The bearing holder (33) is a stainless steel toothed ring with 20 teeth 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 soft teeth of the bearing holder.

In this condition when the weight of the antennas is very large the radial
vertical force generated by it's weight is not absorbed by the balls but  is
completely applied over the teeth and so the 20 balls will be forced to
separate and they spread away one from the other.

This load is responsible to wear out, to deform and to cut the teeth of
the bearing holder but as soon only one or two teeth are broken then
the distance from the balls decreases at a point that the boom tube sandwich
gear (31) has room to fall down a little bit so that the distance between
it and the assembly gear (9) i.e. the pinion  increases up to a point that
it fail to come into gear with the pinion (9)

To cure this problem and prevent damages between the tooths of pinion and
boom tube sandwich gear (31) I have removed the bearing holder (33) but
I have filled the grooves with black molibden grease adding into it , I do
not remember exacly if two or tree more same size balls in order to replace
the original room occuped by the teeth and this rotator is actually running
without problems from several years now.

I hope this helps

73" de

i8CVS Domenico

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