----- Original Message ----- From: "Andrew" WA9WUA@embarqmail.com To: amsat-bb@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@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 outside.

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